Genetic testing of children with familial tall stature: is it worth doing?

CONTEXT

Familial tall stature (FTS) is considered to be a benign variant of growth with a presumed polygenic etiology. However, monogenic disorders with possible associated pathological features could also be hidden under the FTS phenotype.

OBJECTIVES

To elucidate the genetic etiology in families with FTS and to describe their phenotype in detail.

DESIGN, SETTINGS AND PATIENTS

Children with FTS (height in both the child and his/her taller parent >2 SD) referred to the Endocrinology center of Motol University Hospital were enrolled to the study. Their DNA was examined cytogenetically and via next-generation sequencing panel of 786 genes associated with growth. The genetic results were evaluated by the American College of Molecular Genetics and Genomics guidelines. All of the participants underwent standard endocrinological examination followed by specialized anthropometric evaluation.

RESULTS

In total, 34 children (19 girls) with FTS were enrolled in the study. Their median height and their taller parent's height were 3.1 SD and 2.5 SD, respectively. The genetic cause of FTS was elucidated in 11/34 (32.4%) children (47, XXX and 47, XYY karyotypes, SHOX duplication, and causative variants in NSD1 [in 2], SUZ12 [in 2], FGFR3, CHD8, GPC3, and PPP2R5D genes). Ten children had absent syndromic sings and 24 had dysmorphic features.

CONCLUSION

Monogenic (and cytogenetic) etiology of FTS can be found among children with FTS. Genetic examination should be considered in all children with FTS regardless of the presence of dysmorphic features.

Paediatric diabetes subtypes in a consanguineous population: a single-centre cohort study from Kurdistan, Iraq

AIMS/HYPOTHESIS

Monogenic diabetes is estimated to account for 1-6% of paediatric diabetes cases in primarily non-consanguineous populations, while the incidence and genetic spectrum in consanguineous regions are insufficiently defined. In this single-centre study we aimed to evaluate diabetes subtypes, obtain the consanguinity rate and study the genetic background of individuals with syndromic and neonatal diabetes in a population with a high rate of consanguinity.

METHODS

Data collection was carried out cross-sectionally in November 2021 at the paediatric diabetic clinic, Dr Jamal Ahmad Rashed Hospital, in Sulaimani, Kurdistan, Iraq. At the time of data collection, 754 individuals with diabetes (381 boys) aged up to 16 years were registered. Relevant participant data was obtained from patient files. Consanguinity status was known in 735 (97.5%) participants. Furthermore, 12 families of children with neonatal diabetes and seven families of children with syndromic diabetes consented to genetic testing by next-generation sequencing. Prioritised variants were evaluated using the American College of Medical Genetics and Genomics guidelines and confirmed by Sanger sequencing.

RESULTS

A total of 269 of 735 participants (36.5%) with known consanguinity status were offspring of consanguineous families. An overwhelming majority of participants (714/754, 94.7%) had clinically defined type 1 diabetes (35% of them were born to consanguineous parents), whereas only eight (1.1%) had type 2 diabetes (38% consanguineous). Fourteen (1.9%) had neonatal diabetes (50% consanguineous), seven (0.9%) had syndromic diabetes (100% consanguineous) and 11 (1.5%) had clinically defined MODY (18% consanguineous). We found that consanguinity was significantly associated with syndromic diabetes (p=0.0023) but not with any other diabetes subtype. The genetic cause was elucidated in ten of 12 participants with neonatal diabetes who consented to genetic testing (homozygous variants in GLIS3 [sibling pair], PTF1A and ZNF808 and heterozygous variants in ABCC8 and INS) and four of seven participants with syndromic diabetes (homozygous variants in INSR, SLC29A3 and WFS1 [sibling pair]). In addition, a participant referred as syndromic diabetes was diagnosed with mucolipidosis gamma and probably has type 2 diabetes.

CONCLUSIONS/INTERPRETATION

This unique single-centre study confirms that, even in a highly consanguineous population, clinically defined type 1 diabetes is the prevailing paediatric diabetes subtype. Furthermore, a pathogenic cause of monogenic diabetes was identified in 83% of tested participants with neonatal diabetes and 57% of participants with syndromic diabetes, with most variants being homozygous. Causative genes in our consanguineous participants were markedly different from genes reported from non-consanguineous populations and also from those reported in other consanguineous populations. To correctly diagnose syndromic diabetes in consanguineous populations, it may be necessary to re-evaluate diagnostic criteria and include additional phenotypic features such as short stature and hepatosplenomegaly.

Analysis of children with familial short stature: who should be indicated for genetic testing?

Familial short stature (FSS) describes vertically transmitted growth disorders. Traditionally, polygenic inheritance is presumed, but monogenic inheritance seems to occur more frequently than expected. Clinical predictors of monogenic FSS have not been elucidated. The aim of the study was to identify the monogenic etiology and its clinical predictors in FSS children. Of 747 patients treated with growth hormone (GH) in our center, 95 with FSS met the inclusion criteria (pretreatment height ≤-2 SD in child and his/her shorter parent); secondary short stature and Turner/Prader-Willi syndrome were excluded criteria. Genetic etiology was known in 11/95 children before the study, remaining 84 were examined by next-generation sequencing. The results were evaluated by American College of Medical Genetics and Genomics (ACMG) guidelines. Nonparametric tests evaluated differences between monogenic and non-monogenic FSS, an ROC curve estimated quantitative cutoffs for the predictors. Monogenic FSS was confirmed in 36/95 (38%) children. Of these, 29 (81%) carried a causative genetic variant affecting the growth plate, 4 (11%) a variant affecting GH-insulin-like growth factor 1 (IGF1) axis and 3 (8%) a variant in miscellaneous genes. Lower shorter parent's height (P = 0.015) and less delayed bone age (BA) before GH treatment (P = 0.026) predicted monogenic FSS. In children with BA delayed less than 0.4 years and with shorter parent's heights ≤-2.4 SD, monogenic FSS was revealed in 13/16 (81%) cases. To conclude, in FSS children treated with GH, a monogenic etiology is frequent, and gene variants affecting the growth plate are the most common. Shorter parent's height and BA are clinical predictors of monogenic FSS.

SALL4 Phenotype in Four Generations of One Family: An Interplay of the Upper Limb, Kidneys, and the Pituitary

INTRODUCTION

The SALL4 gene encodes a transcription factor that is essential for early embryonic cellular differentiation of the epiblast and primitive endoderm. It is required for the development of neural tissue, kidney, heart, and limbs. Pathogenic SALL4 variants cause Duane-radial ray syndrome (Okihiro syndrome), acro-renal-ocular syndrome, and Holt-Oram syndrome. We report a family with vertical transmission of a SALL4 pathogenic variant leading to radial hypoplasia and kidney dystopia in several generations with additional growth hormone deficiency (GHD) in the proband.

CASE PRESENTATION

Our male proband was born at the 39th week of gestation. He was born small for gestational age (SGA; birth weight 2,550 g, -2.2 SDS; length 47 cm, -2.0 SDS). He had bilateral asymmetrical radial ray malformation (consisting of radial hypoplasia, ulnar flexure, and bilateral aplasia of the thumb) and pelvic kidney dystopia, but no cardiac malformations, clubfoot, ocular coloboma, or Duane anomaly. He was examined for progressive short stature at the age of 3.9 years, where his IGF-1 was 68 μg/L (-1.0 SD), and growth hormone (GH) after stimulation 6.2 μg/L. Other pituitary hormones were normal. A brain CT revealed normal morphology of the cerebral midline and the pituitary. He had a dental anomaly - a central mandibular ectopic canine. MRI could not be done due to the presence of metal after multiple corrective plastic surgeries of his hands. His mother's and father's heights are 152.3 cm (-2.4 SD) and 177.8 cm (-0.4 SD), respectively. His father has a milder malformation of the forearm. The affected paternal grandfather (height 164 cm; -2.3 SD) has a radial ray defect with missing opposition of the thumb. The family reports a similar phenotype of radial dysplasia in the paternal grandfather's mother. The proband started GH therapy at age 6.5 years when his height was 109 cm (-2.8 SDS) and he experienced catch-up growth as expected in GHD. Puberty started spontaneously at the age of 12.5 years. At age 13, his height was 158.7 cm (-0.2 SDS). Whole-exome sequencing revealed a nonsense variant in the SALL4 gene c.1717C>T (p.Arg573Ter) in the proband, his father, and paternal grandfather.

CONCLUSION

This is the first observation of a patient with a congenital upper limb defect due to a pathogenic SALL4 variant who has isolated GHD with no apparent cerebral or facial midline anomaly and has been successfully treated with growth hormone.

Integrative Role of the SALL4 Gene: From Thalidomide Embryopathy to Genetic Defects of the Upper Limb, Internal Organs, Cerebral Midline, and Pituitary

BACKGROUND

The thalidomide disaster resulted in tremendous congenital malformations in more than 10,000 children in the late 1950s and early 1960s.

SUMMARY

Although numerous putative mechanisms were proposed to explain thalidomide teratogenicity, it was confirmed only recently that thalidomide, rather its derivative 5-hydroxythalidomide (5HT) in a complex with the cereblon protein, interferes with early embryonic transcriptional regulation. 5HT induces selective degradation of SALL4, a principal transcriptional factor of early embryogenesis. Genetic syndromes caused by pathogenic variants of the SALL4 gene phenocopy thalidomide embryopathy with congenital malformations ranging from phocomelia, reduced radial ray, to defects of the heart, kidneys, ear, eye, and possibly cerebral midline and pituitary. SALL4 interacts with TBX5 and a handful of other transcriptional regulators and downregulates the Sonic hedgehog signaling pathway. Cranial midline defects, microcephaly, and short stature due to growth hormone deficiency have been occasionally reported in children carrying SALL4 pathogenic variants associated with generalized stunting of growth rather than just the loss of height attributable to the shortening of leg bones in many children with thalidomide embryopathy.

KEY MESSAGES

Thus, SALL4 joins the candidate gene list for monogenic syndromic pituitary insufficiency. In this review, we summarize the journey from the thalidomide disaster through the functions of the SALL4 gene to its link to the hormonal regulation of growth.

The Genetic Landscape of Children Born Small for Gestational Age with Persistent Short Stature

INTRODUCTION

Among children born small for gestational age, 10-15% fail to catch up and remain short (SGA-SS). The underlying mechanisms are mostly unknown. We aimed to decipher genetic aetiologies of SGA-SS within a large single-centre cohort.

METHODS

Out of 820 patients treated with growth hormone (GH), 256 were classified as SGA-SS (birth length and/or birth weight <-2 SD for gestational age and life-minimum height <-2.5 SD). Those with the DNA triplet available (child and both parents) were included in the study (176/256). Targeted testing (karyotype/FISH/MLPA/specific Sanger sequencing) was performed if a specific genetic disorder was clinically suggestive. All remaining patients underwent MS-MLPA to identify Silver-Russell syndrome, and those with unknown genetic aetiology were subsequently examined using whole-exome sequencing or targeted panel of 398 growth-related genes. Genetic variants were classified using ACMG guidelines.

RESULTS

The genetic aetiology was elucidated in 74/176 (42%) children. Of these, 12/74 (16%) had pathogenic or likely pathogenic (P/LP) gene variants affecting pituitary development (LHX4, OTX2, PROKR2, PTCH1, POU1F1), the GH-IGF-1 or IGF-2 axis (GHSR, IGFALS, IGF1R, STAT3, HMGA2), 2/74 (3%) the thyroid axis (TRHR, THRA), 17/74 (23%) the cartilaginous matrix (ACAN, various collagens, FLNB, MATN3), and 7/74 (9%) the paracrine chondrocyte regulation (FGFR3, FGFR2, NPR2). In 12/74 (16%), we revealed P/LP affecting fundamental intracellular/intranuclear processes (CDC42, KMT2D, LMNA, NSD1, PTPN11, SRCAP, SON, SOS1, SOX9, TLK2). SHOX deficiency was found in 7/74 (9%), Silver-Russell syndrome in 12/74 (16%) (11p15, UPD7), and miscellaneous chromosomal aberrations in 5/74 (7%) children.

CONCLUSIONS

The high diagnostic yield sheds a new light on the genetic landscape of SGA-SS, with a central role for the growth plate with substantial contributions from the GH-IGF-1 and thyroid axes and intracellular regulation and signalling.

Karyotyping of Lymphocytes and Epithelial Cells of Distinct Embryonic Origin Does Not Help to Predict the Turner Syndrome Features

BACKGROUND

In Turner syndrome (TS), fluorescent in situ hybridization (FISH) karyotyping offers an alternative to classical karyotyping.

OBJECTIVE

We tested the added value of FISH karyotyping from lymphocytes (mesodermal origin), buccal cells (ectodermal origin), and a rear-tongue smear (endodermal origin) to determine the 45,X cell line fraction and its impact on patient phenotype.

DESIGN AND PATIENTS

Classical karyotyping and three FISH assays were done in 153 girls and women previously diagnosed with TS in four university hospitals. The 45,X cell line fraction was determined for each method and correlated with the major phenotypic signs.

RESULTS

Classical karyotyping identified 45,X/46,XX mosaicism in 77/153 subjects (50%), 45,X monosomy in 52/153 (34%), and other karyotypes in 24/153 (16%). FISH from lymphocytes verified 45,X in 47/52 original cases, whereas 4/52 had 45,X/46,XX and 1/52 45,X/47,XYY mosaicism. The 45,X cell line fraction was higher in FISH from lymphocytes compared to classical karyotyping (median 86.4% vs. 70.0%; p < 0.001), while there was no difference for FISH from buccal or rear-tongue smear cells. The mean 45,X cell line fraction was more abundant in patients with several of the characteristic phenotypic signs compared to patients without them (p < 0.01), but the predictive power was insufficient.

CONCLUSION

FISH analysis confirmed the findings of classical karyotyping; only a few 45,X monosomy cases were reclassified as mosaics. The 45,X cell line fraction did not show clinically meaningful prediction of the phenotype. FISH analysis of buccal or rear-tongue epithelial cells may be a non-inferior, less invasive alternative to classical karyotyping.

Treatment Burden of Weekly Somatrogon vs Daily Somatropin in Children With Growth Hormone Deficiency: A Randomized Study

Context

Somatrogon is a long-acting recombinant human growth hormone treatment developed as a once-weekly treatment for pediatric patients with growth hormone deficiency (GHD).

Objective

Evaluate patient and caregiver perceptions of the treatment burden associated with the once-weekly somatrogon injection regimen vs a once-daily Somatropin injection regimen.

Methods

Pediatric patients (≥3 to <18 years) with GHD receiving once-daily somatropin at enrollment were randomized 1:1 to Sequence 1 (12 weeks of once-daily Somatropin, then 12 weeks of once-weekly somatrogon) or Sequence 2 (12 weeks of once-weekly somatrogon, then 12 weeks of once-daily Somatropin). Treatment burden was assessed using validated questionnaires completed by patients and caregivers. The primary endpoint was the difference in mean overall life interference (LI) total scores after each 12-week treatment period (somatrogon vs Somatropin), as assessed by questionnaires.

Results

Of 87 patients randomized to Sequence 1 (n = 43) or 2 (n = 44), 85 completed the study. Once-weekly somatrogon had a significantly lower treatment burden than once-daily Somatropin, based on mean overall LI total scores after somatrogon (8.63) vs Somatropin (24.13) treatment (mean difference –15.49; 2-sided 95% CI –19.71, –11.27; P < .0001). Once-weekly somatrogon was associated with greater convenience, higher satisfaction with treatment experience, and less LI. The incidence of treatment-emergent adverse events (TEAEs) for Somatropin and somatrogon was 44.2% and 54.0%, respectively. No severe or serious AEs were reported.

Conclusion

In pediatric patients with GHD, once-weekly somatrogon had a lower treatment burden and was associated with a more favorable treatment experience than once-daily Somatropin.

Search for a time- and cost-saving genetic testing strategy for maturity-onset diabetes of the young

AIMS

Correct genetic diagnosis of maturity-onset diabetes of the young (MODY) is beneficial for person's diabetes management compared to no genetic testing. Aim of the present study was a search for optimal time- and cost-saving strategies by comparing two approaches of genetic testing of participants with clinical suspicion of MODY.

METHODS

A total of 121 consecutive probands referred for suspicion of MODY (Group A) were screened using targeted NGS (tNGS), while the other 112 consecutive probands (Group B) underwent a single gene test based on phenotype, and in cases of negative findings, tNGS was conducted. The study was performed in two subsequent years. The genetic results, time until reporting of the final results and financial expenses were compared between the groups.

RESULTS

MODY was confirmed in 30.6% and 40.2% probands from Groups A and B, respectively; GCK-MODY was predominant (72.2% in Group A and 77.8% in Group B). The median number of days until results reporting was 184 days (IQR 122-258) in Group A and 91 days (44-174) in Group B (p < 0.00001). Mean costs per person were higher for Group A (639 ± 30 USD) than for Group B (584 ± 296 USD; p = 0.044).

CONCLUSIONS

The two-step approach represented a better strategy for genetic investigation of MODY concerning time and costs compared to direct tNGS. Although a single-gene investigation clarified the diabetes aetiology in the majority of cases, tNGS could reveal rare causes of MODY and expose possible limitations of both standard genetic techniques and clinical evaluation.

Invaluable Role of Consanguinity in Providing Insight into Paediatric Endocrine Conditions: Lessons Learnt from Congenital Hyperinsulinism, Monogenic Diabetes, and Short Stature

Consanguineous families have often played a role in the discovery of novel genes, especially in paediatric endocrinology. At this time, it has been estimated that over 8.5% of all children worldwide have consanguineous parents. Consanguinity is linked to demographic, cultural, and religious practises and is more common in some areas around the world than others. In children with endocrine conditions from consanguineous families, there is a greater probability that a single-gene condition with autosomal recessive inheritance is causative. From 1966 and the first description of Laron syndrome, through the discovery of the first KATP channel genes ABCC8 and KCNJ11 causing congenital hyperinsulinism (CHI) in the 1990s, to recent discoveries of mutations in YIPF5 as the first cause of monogenic diabetes due to the disruption of the endoplasmic reticulum (ER)-to-Golgi trafficking in the β-cell and increased ER stress; positive genetic findings in children from consanguinity have been important in elucidating novel genes and mechanisms of disease, thereby expanding knowledge into disease pathophysiology. The aim of this narrative review was to shed light on the lessons learned from consanguineous pedigrees with the help of 3 fundamental endocrine conditions that represent an evolving spectrum of pathophysiological complexity - from CHI, a typically single-cell condition, to monogenic diabetes which presents with uniform biochemical parameters (hyperglycaemia and glycosuria), despite varying aetiologies, up to the genetic regulation of human growth - the most complex developmental phenomenon.

Nationwide observational study of paediatric inflammatory multisystem syndrome temporally associated with SARS-CoV-2 (PIMS-TS) in the Czech Republic

The worldwide outbreak of the novel 2019 coronavirus disease (COVID-19) has led to recognition of a new immunopathological condition: paediatric inflammatory multisystem syndrome (PIMS-TS). The Czech Republic (CZ) suffered from one of the highest incidences of individuals who tested positive during pandemic waves. The aim of this study was to analyse epidemiological, clinical, and laboratory characteristics of all cases of paediatric inflammatory multisystem syndrome (PIMS-TS) in the Czech Republic (CZ) and their predictors of severe course. We performed a retrospective-prospective nationwide observational study based on patients hospitalised with PIMS-TS in CZ between 1 November 2020 and 31 May 2021. The anonymised data of patients were abstracted from medical record review. Using the inclusion criteria according to World Health Organization definition, 207 patients with PIMS-TS were enrolled in this study. The incidence of PIMS-TS out of all SARS-CoV-2-positive children was 0.9:1,000. The estimated delay between the occurrence of PIMS-TS and the COVID-19 pandemic wave was 3 weeks. The significant initial predictors of myocardial dysfunction included mainly cardiovascular signs (hypotension, oedema, oliguria/anuria, and prolonged capillary refill). During follow-up, most patients (98.8%) had normal cardiac function, with no residual findings. No fatal cases were reported.Conclusions: A 3-week interval in combination with incidence of COVID-19 could help increase pre-test probability of PIMS-TS during pandemic waves in the suspected cases. Although the parameters of the models do not allow one to completely divide patients into high and low risk groups, knowing the most important predictors surely could help clinical management.

Isolated growth hormone deficiency in children with vertically transmitted short stature: What do the genes tell us?

INTRODUCTION

The growth hormone deficiency (GHD) diagnosis is controversial especially due to low specificity of growth hormone (GH) stimulation tests. It is therefore believed that children diagnosed with GHD form a heterogeneous group with growth disorder frequently independent on GH function. No study evaluating the complex etiology of growth failure in children with diagnosed GHD has been performed thus far.

AIMS

To discover genetic etiology of short stature in children with diagnosed GHD from families with short stature.

METHODS

Fifty-two children diagnosed with primary GHD and vertically transmitted short stature (height SDS in the child and his/her shorter parent <-2 SD) were included to our study. The GHD diagnosis was based on growth data suggestive of GHD, absence of substantial disproportionality (sitting height to total height ratio <-2 SD or >+2 SD), IGF-1 levels <0 for age and sex specific SD and peak GH concentration <10 ug/L in two stimulation tests. All children were examined using next-generation sequencing methods, and the genetic variants were subsequently evaluated by American College of Medical Genetics standards and guidelines.

RESULTS

The age of children at enrollment into the study was 11 years (median, IQR 9-14 years), their height prior to GH treatment was -3.0 SD (-3.6 to -2.8 SD), IGF-1 concentration -1.4 SD (-2.0 to -1.1 SD), and maximal stimulated GH 6.3 ug/L (4.8-7.6 ug/L). No child had multiple pituitary hormone deficiency or a midbrain region pathology. Causative variant in a gene that affects growth was discovered in 15/52 (29%) children. Of them, only 2 (13%) had a genetic variant affecting GH secretion or function (GHSR and OTX2). Interestingly, in 10 (67%) children we discovered a primary growth plate disorder (ACAN, COL1A2, COL11A1, COL2A1, EXT2, FGFR3, NF1, NPR2, PTPN11 [2x]), in one (7%) a genetic variant impairing IGF-1 action (IGFALS) and in two (12%) a variant in miscellaneous genes (SALL4, MBTPS2).

CONCLUSIONS

In children with vertically transmitted short stature, genetic results frequently did not correspond with the clinical diagnosis of GH deficiency. These results underline the doubtful reliability of methods standardly used to diagnose GH deficiency.

Management of growth failure and other endocrine aspects in patients with Noonan syndrome across Europe: A sub-analysis of a European clinical practice survey

AIM

To date, there is a lack of international guidelines regarding the management of the endocrine features of individuals with Noonan syndrome (NS). The aim was to develop a clinical practice survey to gather information on current treatment and management of these patients across Europe.

MATERIALS AND METHODS

A group of 10 experts from three clinical specialities involved in the management of NS patients (clinical geneticists, paediatric endocrinologists, and paediatric cardiologists) developed a 60-question clinical practice survey. The questionnaire was implemented in Survey Monkey and sent to physicians from these three specialities via European/national societies. Contingency tables and the Chi-Squared test for independence were used to examine differences between specialities and countries.

RESULTS

In total, responses of 364 specialists (paediatric endocrinologists, 40%; geneticists, 30%; paediatric cardiologists, 30%) from 20 European countries were analysed. While endocrinologists mostly referred to national growth charts for the general population, geneticists mostly referred to NS-specific growth charts. Approximately half of the endocrinologists perform growth hormone (GH) stimulation tests in short patients with low IGF1 levels. Two thirds of endocrinologists begin GH treatment for short patients in early childhood (4-6.9 years), and over half of them selected a threshold of -2 standard deviation score (SDS) according to national growth charts. The main concerns about GH treatment appear to be presence of hypertrophic cardiomyopathy (HCM) (59%), increased risk of malignancy (46%), and limited efficacy (31%). When asked if they consider HCM as a contraindication for GH treatment, one third of respondents skipped this question, and among those who replied, two thirds selected 'cannot answer', suggesting a high level of uncertainty. A total of 21 adverse cardiac responses to GH treatment were reported. Although most respondents had not encountered any malignancy during GH treatment, six malignancies were reported. Finally, about half of the endocrinologists expected a typical final height gain of 1-1.5 SDS with GH treatment.

CONCLUSION

This survey describes for the first time the current clinical practice of endocrine aspects of NS across Europe and helps us to identify gaps in the management but also in the knowledge of this genetic disorder.

Management of cardiac aspects in children with Noonan syndrome - results from a European clinical practice survey among paediatric cardiologists

BACKGROUND

The majority of children with Noonan syndrome (NS) or other diseases from the RASopathy spectrum suffer from congenital heart disease. This study aims to survey cardiac care of this patient cohort within Europe.

METHODS

A cross-sectional exploratory survey assessing the treatment and management of patients with NS by paediatric endocrinologists, cardiologists and clinical geneticists was developed. This report details responses of 110 participating paediatric cardiologists from multiple countries.

RESULTS

Most paediatric cardiologists responding to the questionnaire were associated with university hospitals, and most treated <10 patients/year with congenital heart disease associated with the NS spectrum. Molecular genetic testing for diagnosis confirmation was initiated by 81%. Half of the respondents reported that patients with NS and congenital heart disease typically present <1y of age, and that a large percentage of affected patients require interventions and pharmacotherapy early in life. A higher proportion of infant presentation and need for pharmacotherapy was reported by respondents from Germany and Sweden than from France and Spain (p = 0.031; p = 0.014; Fisher's exact test). Older age at first presentation was reported more from general hospitals and independent practices than from university hospitals (p = 0.031). The majority of NS patients were followed at specialist centres, but only 37% reported that their institution offered dedicated transition clinic to adult services. Very few NS patients with hypertrophic cardiomyopathy (HCM) were reported to carry implantable cardioverter defibrillators for sudden cardiac death prevention. Uncertainty was evident in regard to growth hormone treatment in patients with NS and co-existing HCM, where 13% considered it not a contra-indication, 24% stated they did not know, but 63% considered HCM either a possible (20%) or definite (15%) contraindication, or a cause for frequent monitoring (28%). Regarding adverse reactions for patients with NS on growth hormone therapy, 5/19 paediatric cardiology respondents reported a total of 12 adverse cardiac events.

CONCLUSIONS

Congenital heart disease in patients with NS or other RASopathies is associated with significant morbidity during early life, and specialty centre care is appropriate. More research is needed regarding the use of growth hormone in patients with NS with congenital heart disease, and unmet medical needs have been identified.

European Medical Education Initiative on Noonan syndrome: A clinical practice survey assessing the diagnosis and clinical management of individuals with Noonan syndrome across Europe

INTRODUCTION

Noonan syndrome (NS) is a rare genetic disorder caused by mutations in genes encoding components of the RAS/mitogen-activated protein kinase (MAPK) signalling pathway. Patients with NS exhibit certain characteristic features, including cardiac defects, short stature, distinctive facial appearance, skeletal abnormalities, cognitive deficits, and predisposition to certain cancers. Here, a clinical practice survey was developed to learn more about differences in the diagnosis and management of this disease across Europe. The aim was to identify gaps in the knowledge and management of this rare disorder.

MATERIALS AND METHODS

The European Medical Education Initiative on NS, which comprised a group of 10 experts, developed a 60-question clinical practice survey to gather information from European physicians on the diagnosis and clinical management of patients with diseases in the NS phenotypic spectrum. Physicians from three specialities (clinical genetics, paediatric endocrinology, paediatric cardiology) were invited to complete the survey by several national and European societies. Differences in answers provided by respondents between specialities and countries were analysed using contingency tables and the Chi-Squared test for independence. The Friedman's test was used for related samples.

RESULTS

Data were analysed from 364 respondents from 20 European countries. Most respondents came from France (21%), Spain (18%), Germany (16%), Italy (15%), United Kingdom (8%) and the Czech Republic (6%). Respondents were distributed evenly across three specialities: clinical genetics (30%), paediatric endocrinology (40%) and paediatric cardiology (30%). Care practices were generally aligned across the countries participating in the survey. Delayed diagnosis did not emerge as a critical issue, but certain unmet needs were identified, including transition of young patients to adult medical services and awareness of family support groups.

CONCLUSION

Data collected from this survey provide a comprehensive summary of the diagnosis and clinical management practices for patients with NS across different European countries.

Blastocystis in the faeces of children from six distant countries: prevalence, quantity, subtypes and the relation to the gut bacteriome

Background

Blastocystis is a human gut symbiont of yet undefined clinical significance. In a set of faecal samples collected from asymptomatic children of six distant populations, we first assessed the community profiles of protist 18S rDNA and then characterized Blastocystis subtypes and tested Blastocystis association with the faecal bacteriome community.

Methods

Stool samples were collected from 244 children and young persons (mean age 11.3 years, interquartile range 8.1–13.7) of six countries (Azerbaijan 51 subjects, Czechia 52, Jordan 40, Nigeria 27, Sudan 59 and Tanzania 15). The subjects showed no symptoms of infection. Amplicon profiling of the 18S rDNA was used for verification that Blastocystis was the most frequent protist, whereas specific real-time PCR showed its prevalence and quantity, and massive parallel amplicon sequencing defined the Blastocystis subtypes. The relation between Blastocystis and the stool bacteriome community was characterized using 16S rDNA profiling.

Results

Blastocystis was detected by specific PCR in 36% (88/244) stool samples and was the most often observed faecal protist. Children from Czechia and Jordan had significantly lower prevalence than children from the remaining countries. The most frequent subtype was ST3 (49%, 40/81 sequenced samples), followed by ST1 (36%) and ST2 (25%). Co-infection with two different subtypes was noted in 12% samples. The faecal bacteriome had higher richness in Blastocystis-positive samples, and Blastocystis was associated with significantly different community composition regardless of the country (p < 0.001 in constrained redundancy analysis). Several taxa differed with Blastocystis positivity or quantity: two genera of Ruminococcaceae were more abundant, while Bifidobacterium, Veillonella, Lactobacillus and several other genera were undrerrepresented.

Conclusions

Asymptomatic children frequently carry Blastocystis, and co-infection with multiple distinct subtypes is not exceptional. Prevalence and quantity of the organism clearly differ among populations. Blastocystis is linked to both faecal bacteriome diversity and its composition.

Graphical Abstract

Supplementary Information

The online version contains supplementary material available at 10.1186/s13071-021-04859-3.

Eukaryotic viruses in the fecal virome at the onset of type 1 diabetes: A study from four geographically distant African and Asian countries

OBJECTIVES

Studies of the fecal virome in type 1 diabetes (T1D) have been limited to populations of Europe and the United States. We therefore sought to characterize the stool virome in children after onset of T1D and in matched control subjects from four geographically distant African and Asian countries.

METHODS

Samples of stool were collected from 73 children and adolescents shortly after T1D onset (Azerbaijan 19, Jordan 20, Nigeria 14, Sudan 20) and 105 matched control subjects of similar age and locale. Metagenomic sequencing of the DNA and RNA virome was performed, and virus positivity was defined as more than 0.001% of reads of the sample. Selected viruses were also quantified using real-time PCR. Conditional logistic regression was used to model associations with eukaryotic virus positivity.

RESULTS

Signals of 387 different viral species were detected; at least one eukaryotic virus was detected in 71% case and 65% control samples. Neither of observed eukaryotic virus species or genera differed in frequency between children with T1D and controls. There was a suggestive association of the total count of different viral genera per sample between cases (1.45 genera) and controls (1.10 genera, OR 1.24, 95%CI 0.98-1.57), and an unplanned subanalysis suggested marginally more frequent endogenous retrovirus signal in cases (in 28.8% vs. in 8.6% controls, OR = 4.55, 95%CI 1.72-12).

CONCLUSIONS

No clear and consistent association with T1D was observed in the fecal viromes from four distant non-European populations. The finding of borderline associations of human endogenous retroviruses merits further exploration.

Familial Short Stature-A Novel Phenotype of Growth Plate Collagenopathies

CONTEXT

Collagens are the most abundant proteins in the human body. In a growth plate, collagen types II, IX, X, and XI are present. Defects in collagen genes cause heterogeneous syndromic disorders frequently associated with short stature. Less is known about oligosymptomatic collagenopathies.

OBJECTIVE

This work aims to evaluate the frequency of collagenopathies in familial short stature (FSS) children and to describe their phenotype, including growth hormone (GH) treatment response.

METHODS

Eighty-seven FSS children (pretreatment height ≤ -2 SD both in the patient and his or her shorter parent) treated with GH were included in the study. Next-generation sequencing was performed to search for variants in the COL2A1, COL9A1, COL9A2, COL9A3, COL10A1, COL11A1, and COL11A2 genes. The results were evaluated using American College of Medical Genetics and Genomics guidelines. The GH treatment response of affected children was retrospectively evaluated.

RESULTS

A likely pathogenic variant in the collagen gene was found in 10 of 87 (11.5%) children. Detailed examination described mild asymmetry with shorter limbs and mild bone dysplasia signs in 2 of 10 and 4 of 10 affected children, respectively. Their growth velocity improved from a median of 5.3 cm/year to 8.7 cm/year after 1 year of treatment. Their height improved from a median of -3.1 SD to -2.6 SD and to -2.2 SD after 1 and 3 years of therapy, respectively. The final height reached by 4 of 10 children differed by -0.67 to +1.0 SD and -0.45 to +0.5 SD compared to their pretreatment height and their affected untreated parent's height, respectively.

CONCLUSION

Oligosymptomatic collagenopathies are a frequent cause of FSS. The short-term response to GH treatment is promising.

Stratifying the Genetic Aetiology in Children Born Small for Gestational Age With Persistent Short Stature (SGA-SS)

Background: Ten percent of children born small for gestational age with a birth weight and/or length of below -2 SD for their gestational age fail to catch-up and remain short during childhood (SGA-SS). The etiology of SGA-SS is heterogeneous: some children have specific phenotypic features that allow targeted genetic testing; in others, elucidating genetic or environmental background is more challenging. Aim: To decipher genetic etiologies among a large single-center cohort of SGA-SS children and to stratify them according to molecular mechanisms leading to pre- and postnatal growth failure. Patients/Methods: In our center 447 children (223 females) fulfilled the criteria of SGA-SS. Of these 182 families agreed to take part and offered the child’s and both parents’ DNA for genetic testing by a panel of 399 growth-related genes, or by Whole Exome Sequencing (WES). The results were processed by a bioinformatic pipeline and detected variants were filtered using variant analysis software. Pathogenic or likely pathogenic variants (according to ACMG standards and guidelines) were confirmed by Sanger sequencing. Results: The genetic etiology was elucidated in 73/182 (40%) children so far. We confirmed (likely) pathogenic gene variants affecting pituitary development and/or the GH-IGF-1 axis in 10/73 (14%) patients (PTCH1, HGMA2 [in two], OTX2, LHX4, GHSR, STAT3, IGFALS, IGF1R [in two]), abnormal components of cartilaginous matrix in 17/73 (23%) (ACAN [in two], FLNB [in three], FBLN5, COL11A1[in four], COL1A2, COL2A1[in five], MATN3), impaired paracrine regulation of chondrocytes in 4/73 (6%) (NPR2 [in three], FGFR3), SHOX gene defects in 12/73 (16%), gene variants affecting other components of intracellular regulation and signaling in 9/73 (12%) (CDC42, KMT2A, KMT2D, NSD1, SRCAP, PRG4, PTPN11, SON, LMNA), Silver-Russell syndrome (11p15 [in seven] or UPD7) in 11/73 (15%), and miscellaneous single-gene or chromosomal conditions (TRPS1, TRHR, RAI1, chromosomal microdeletions and/or translocations) in an additional ten (14%) children. Conclusions: In our study we showed that by using current genetic techniques we were able to elucidate the genetic cause in a significant number of patients born SGA-SS. The genetic etiology spectrum of SGA-SS reflects the complex system of growth regulation, with a significant role of growth plate genes that are causative in 33/73 (45%) cases clarified thus far. Acknowledgements: The study was co-funded by grants AZV NV18-07-00283 and GAUK 408120.

Perception of Treatment Burden With Once Weekly Somatrogon vs Once Daily Genotropin in Pediatric Patients With Growth Hormone Deficiency (GHD): Results From a Randomized Phase 3 Study

Background: Somatrogon is a long-acting recombinant human growth hormone (rhGH) comprised of the amino acid sequence of hGH and 3 copies of the carboxy-terminal peptide from human chorionic gonadotropin. Somatrogon is being developed as a once weekly subcutaneous (SC) injectable treatment for pediatric patients (pts) with GHD.

Aims: To evaluate patient and caregiver perceptions of the treatment burden associated with a once weekly somatrogon SC injection schedule compared with a once daily Genotropin SC injection schedule.

Methods: In this phase 3 (NCT03831880), open-label, crossover study, pediatric pts (3 to &lt;18 years) with GHD on at least 3 months stable rhGH therapy were randomized 1:1 to receive treatment according to 1 of 2 sequences: Sequence #1, 12 weeks of Genotropin once daily followed by 12 weeks of somatrogon once weekly; Sequence #2, 12 weeks of somatrogon once weekly followed by 12 weeks of Genotropin once daily. The primary objective of the study was to evaluate treatment burden assessed as the difference between mean overall Life Interference (LI) total scores after each 12-week treatment period of weekly somatrogon and daily Genotropin. Secondary objectives further assessed treatment experience of pts and caregivers after each treatment period and their comparison of both treatments at the end of the study. A recently developed, validated dyad questionnaire (Turner-Bowker DM et al, 2020) was administered as an electronic Patient Reported Outcome to collect all assessments.

Results: Eighty-seven pts were randomized to Sequence #1 (n=43) or Sequence #2 (n=44) with 85 pts completing the study. Somatrogon administered as a once weekly injection had a lower (statistically significant) treatment burden than Genotropin administered as a once daily injection, based on the mean overall LI total scores after somatrogon (8.63) vs Genotropin (24.13) treatment (mean difference: -15.49; two-sided 95% CI: [-19.71, -11.27]; P &lt;0.0001). Compared with once daily Genotropin, once weekly somatrogon was associated with greater convenience, higher satisfaction with treatment experience, and less life interference for the caregiver. A higher proportion of pts preferred once weekly somatrogon and demonstrated a greater intent to comply with treatment. The proportion of pts who experienced at least one treatment-emergent adverse event (TEAE) with Genotropin and somatrogon treatment were 44.2% and 54.0%, respectively. Injection site pain was the most common TEAE during the Genotropin (12.8%) and somatrogon (14.9%) treatment periods and was rated as mild in most cases. No severe or serious adverse events were reported.

Conclusions: In pediatric pts with GHD, compared with Genotropin administered once daily, somatrogon administered once weekly has a lower treatment burden as shown by less life interference, and is associated with a more favorable treatment experience.

Growth Plate Genes Are Key Regulators of Growth: Lessons Learned From Children of Consanguineous Families From Kurdistan, Iraq

Introduction: The genetic basis of human growth regulation has only been partly elucidated thus far. Therefore, finding causative genes in patients with short stature help in understanding precise pathophysiological mechanisms, establishing genotype-phenotype relationships and optimizing treatment. In order to extend our knowledge about the genes involved in short stature, we studied a unique cohort of consanguineous families with children with short stature from Sulaymani in Kurdistan, Iraq. Patients and Methods: Fifty-five consanguineous families, with children shorter than -2.3SDS at the time of examination (median height -3.3SDS, range -2.3 to -15SDS), who were examined at the endocrine outpatient clinic of the Department of Pediatrics, Sulaymani University College of Medicine between January 2018 and February 2020, were included in the study. In families with more than one child with short stature, the shorter sibling was selected as the proband (median age 8 years, range 1 - 15 years). Three probands were subsequently excluded due to the diagnosis of Turner’s syndrome and Edward’s syndrome Consent was obtained from all families and probands’ DNA was analyzed by Whole Exome Sequencing (WES) methods. The data were processed by a bioinformatic pipeline and detected variants were filtered using variant analysis software. Selected potentially pathogenic variants were confirmed using Sanger sequencing methods and evaluated by the American College of Medical Genetics (ACMG) standards and guidelines. Results: A monogenic cause of short stature, which explained the patient phenotype, was elucidated in 13 of 26 families who were analyzed thus far. Seven families had multiple affected children making a total of 22 patients with a positive genetic diagnosis. Pathogenic or likely pathogenic variants (according to the ACMG standards) were found in genes involved in the GH-IGF-1 axis (GHR), in the extracellular matrix of the growth plate (COL1A2, MMP13, LTBP3, and ADAMTS17), in the regulation of chondrocytes (NPR2 and CTSK), transporter coding genes (SLC34A3), and other genes (PTCH1, GALNS, DNACJ21, ZSWIM6, GNPTG). Among them, there are 9 novel variants and 10 homozygous variants including variants in genes causing syndromic short stature. Unexpectedly, we successfully identified three cases of autosomal dominant short stature (variants in genes NPR2, COL1A2, PTCH1) as well. The remaining probands from 26 families are still being analyzed. Conclusion: With the help of NGS methods, we have successfully elucidated the genetic cause of short stature in nearly 50% of patients who were analyzed thus far. These results further strength the concept that genes affecting the growth plate (chondrocytes and the extracellular matrix) play a crucial role in growth regulation. Acknowledgements: The study was co-funded by grants AZV 18-07-00283 and GAUK 340420.

Familial Short Stature - a Novel Phenotype of Growth Plate Collagenopathies

Backround: Collagens are the most abundant proteins in the human body. In a growth plate, collagen types II, IX, X and XI are present. Defects in collagen genes cause heterogeneous syndromic disorders frequently associated with asymmetric short stature (e.g. Kniest dysplasia, spondyloepiphyseal dysplasia). Less is known about nonsyndromic collagenopathies - data about their frequency and subtle phenotypic signs are sparse, the information about their response to growth hormone (GH) treatment is lacking completely.

Aim: To evaluate the frequency of collagenopathies in familial short stature (FSS) children and to describe their phenotype, including growth hormone (GH) treatment response.

Methods: Out of 522 individuals treated in our center with GH from the indication of primary GH deficiency (GHD) or small for gestational age short stature (SGA-SS), 87 children with FSS fulfilled the inclusion criteria (pre-treatment height ≤-2 SD in both patient/their shorter parent, signed written informed consent) and were enrolled to the study. Next-generation sequencing was performed to search for variants in COL2A1, COL9A1, COL9A2, COL9A3, COL10A1, COL11A1 and COL11A2 genes. The results were evaluated using ACMG guidelines. The phenotype of children with (likely) pathogenic variants was described including the short-term GH treatment response (growth velocity and body-height SDS increase over three years of treatment). For statistical evaluation, parametric tests were used, p-values <0.05 were considered significant.

Results: A (likely) pathogenic variant in one of the collagen genes was found in 10/87 (11.5%) children. Their age was 12.5 years (median, range 6-17 years), their pre-treatment height was -3.1 SD (-2.4 to -4.3 SD). Their birth length (median -2.8 SD; range -0.7 to -4.1 SD) was more severely affected than birth weight (median -2.1 SD; range -1.0 to -2.7 SD). Eight children were treated with GH from SGA-SS indication, the remaining 2 were classified as mild GHD (maximal stimulated GH concentration 8.0 and 9.7 ug/l, normal brain MRI and examination of other pituitary hormones). Detailed anthropometric examination described mild asymmetry with shorter limbs and mild bone dysplasia signs (scoliosis, more pronounced lumbar lordosis, genua valga, limited elbow extension) in 2/10 and 4/10 affected children, respectively. Growth velocity improved from a median of 5.3 cm/year to 8.7 cm/year after one year of treatment (p<0.001, paired-sample T-test), height improved from a median of -3.1 SD to -2.2 SD after three years of therapy (p=0.001, ANOVA repeated measures analysis of variants).

Conclusion: Nonsyndromic collagenopathies are a frequent cause of FSS. The short-term response to GH treatment is promising.

Supported by the Ministry of Health, Czech Republic, grant number NV18- 07-00283 and by the research project of the Grant Agency of Charles University of Prague, GAUK 976718.

Growth Hormone Deficiency: Extending the Phenotypic Spectrum of SALL4-Related Disorders

Background: The SALL4 gene encodes sal-like protein 4, a transcription factor with eight zinc finger motifs that is essential for the development of the epiblast and primitive endoderm. In association with TBX5 (T-box), SALL4 is responsible for the establishment and morphogenesis of the thumb. Pathogenic SALL4 variants have been reported to cause Duane-radial ray syndrome (also known as Okihiro syndrome), acro-renal-ocular syndrome and Holt-Oram syndrome. Hereby, we report on a family with radial hypoplasia and kidney dystopia in members of 4 consecutive generations, and short stature due to growth hormone deficiency (GHD) in the proband. Clinical Case: The male proband was born from the 3^rd normal pregnancy at 39th week of gestation. He has no biological siblings. He was born small for gestational age (birth weight 2550 g, length 47 cm - both < 2SD) and had bilateral asymmetrical radial ray malformation consisting of radial hypoplasia, ulnar flexure and bilateral aplasia of the thumb, and pelvic dystopia of his right kidney. He had no cardiac malformations, clubfoot, ocular coloboma or Duane anomaly. He was examined for progressive short stature at the age of 3.9 years, where his IGF-1 was 68 ug/l (-1.0 SD), and peak GH in two stimulation tests was 6.2 ug/l. Other pituitary hormones were normal. His mother’s and father’s heights are 152.3 cm (-2.4 SD), and 177.8 cm (-0.4 SD), respectively. His father has malformation of the forearm that is milder than that of the son. The paternal grandfather is affected as well, with a radial defect with missing opposition of the thumb and height 164 cm (-2.3 SD). The family reports that the phenotype of radial dysplasia was apparent in the paternal grandfather’s mother as well. Due to the suggestive monogenic dominant transmission of the developmental abnormality, we carried out whole exome sequencing that revealed a nonsense variant in the SALL4 gene c.1717C>T (p.Arg573Ter) in the proband, his father, and paternal grandfather. The proband was started with regular GH therapy at age 6.5 years and experienced catch-up growth as expected in GHD. By the age 11 years, his height stabilized at about the 25th percentile in accordance to the mid-parent height with a target height of 171.5 +/- 8.5 cm. Puberty started spontaneously at the age 12.5 years. Conclusion: This is the first case demonstrating a patient with a congenital upper limb defect based on a pathogenic variant of the SALL4 gene where an isolated growth hormone deficiency (GHD) was detected and has been successfully treated with growth hormone. Acknowledgements: Genetic testing was funded by AZV grant NV18-07-00283.

Congenital Hyperinsulinism Caused by Novel Homozygous KATP Channel Gene Variants May Be Linked to Unexplained Neonatal Deaths among Kurdish Consanguineous Families

INTRODUCTION

Neonatal hypoglycemia due to congenital hyperinsulinism (CHI) is a potentially life-threatening condition. Biallelic pathogenic variants in KATP channel subunit genes (ABCC8, KCNJ11), causing severe forms of CHI, are more prevalent in regions with a significant rate of consanguinity and may lead to unexplained neonatal deaths. We hypothesized that KATP channel gene variants are the cause of CHI in three unrelated children from consanguineous Kurdish families with histories of four unexplained neonatal deaths with convulsions.

CASES

(1) A girl presented on the 6th day of life with recurrent hypoglycemic convulsions (blood glucose 2.05 mmol/L, insulin 58 mIU/L, C-peptide 2,242 pmol/L). (2) A girl with severe developmental delay was diagnosed with CHI at 3 years of age (blood glucose 2.78 mmol/L, insulin 8.1 mIU/L, C-peptide 761 pmol/L) despite a history of recurrent hypoglycemia since neonatal age. (3) A girl presented at 3 weeks of age with convulsions and unconsciousness (blood glucose 2.5 mmol/L, insulin 14.6 mIU/L, C-peptide 523 pmol/L). Coding regions of the ABCC8 and KCNJ11 genes were tested by Sanger sequencing. Potential variants were evaluated using the American College of Medical Genetics standards. Three novel causative homozygous variants were found - p.Trp514Ter in the ABCC8 gene (Pt2), and p.Met1Val (Pt1) and p.Tyr26Ter (Pt3) in the KCNJ11 gene.

CONCLUSION

CHI caused by KATP channel variants was elucidated in three children, providing a highly probable retrospective diagnosis for their deceased siblings. Future lives can be saved by timely diagnosis of CHI when encountering a neonate with unexplained seizures or other signs of recurrent and/or persistent hypoglycemia.

Haplotype analysis of the X chromosome in patients with Turner syndrome in order to verify the possible effect of imprinting on selected symptoms

AIMS

Turner syndrome is the only chromosome monosomy that is postnatally compatible with life. The reported incidence of TS is 1 in 2500 liveborn girls. The phenotype of these girls is highly variable, with cardiac abnormalities being life-threatening defects. The aim of the study was to reveal the possible influence of the parental origin of the X chromosome in these patients on a selected phenotype that is associated with Turner syndrome. Selected symptoms and parameters were: a bicuspid aortic valve, aortic coarctation, lymphoedema, pterygium colli, coeliac disease, thyroiditis, otitis media, diabetes mellitus 2, renal abnormalities, spontaneous puberty, and IVF.

METHODS

The X chromosome haplotype was determined for a group of 45,X patients verified by native FISH. A molecular diagnostic method based on the detection of different lengths of X chromosome-linked STR markers using the Argus X-12 QS kit was used to determine the X haplotype.

RESULTS

Our results, analysed by Fisher's exact (factorial) test, suggest independence between the maternal/paternal origin of the inherited X chromosome and the presence of the anomalies that were studied (P=1 to P=0.34).

CONCLUSION

In the group of 45,X patients, who were precisely selected by means of the native FISH method, no correlation was demonstrated with the parental origin of the X chromosome and the observed symptom.

Long-term follow up of carbohydrate metabolism and adverse events after termination of Omnitrope® treatment in children born small for gestational age

BACKGROUND

Recombinant human growth hormone (rhGH) therapy can affect carbohydrate metabolism and lead to impaired glucose tolerance during treatment. In addition, short children born small for gestational age (SGA) are predisposed to metabolic abnormalities. This study assessed the long-term safety of rhGH (Omnitrope®) use in short children born SGA.

METHODS

This was a follow-up observational study of patients from a phase IV study. The baseline visit was the final visit of the phase IV study. Further visits were planned after 6 months (F1), 1 year (F2), 5 years (F3), and 10 years (F4). The primary objective was to evaluate the long-term effect of rhGH treatment on the development of diabetes mellitus; secondary objectives included incidence/severity of adverse events (AEs).

RESULTS

In total, 130 subjects were enrolled in the follow-up study; 99 completed F1, 88 completed F2, and 13 completed F3 (no subject reached F4). The full analysis set for evaluation comprised 118 patients (64 female). Mean (standard deviation) duration of follow up was 39.6 (24.4) months. No subject was newly diagnosed with diabetes. The results for carbohydrate metabolism parameters were consistent with this finding. A total of 144 AEs were reported in 54 subjects; these were mostly of mild-to-moderate intensity (96.5%) and not suspected to be related to previous rhGH treatment (94.4%). Serious AEs (n = 18) were reported in eight patients; three (in one patient) were suspected as possibly related to previous rhGH treatment (anemia, menorrhagia, oligomenorrhoea). One fatal event occurred (sepsis), which was judged as not related to previous rhGH treatment.

CONCLUSIONS

None of the participating subjects, who had all been previously treated with Omnitrope® in a phase IV study, developed diabetes during this follow-up study. In addition, no other unexpected or concerning safety signals were observed.

The contribution of X-chromosome genomic imprinting to the bicuspid aortic valve and aortic coarctation prevalence in women with Turner syndrome

Introduction

Turner syndrome (TS) is caused by the absence or structural abnormality of X chromosome. Compared with the general population, the prevalence of congenital heart defects is significantly higher in women with TS, especially with 45,X karyotype. Moreover, congenital heart defects represent the major risk for aortic dissection in TS individuals.

Purpose

There is a lack of reliable evidence whether the extremely variable cardiovascular phenotype including presence of aortic coarctation (CoA) and bicuspid aortic valve (BAV) in TS women may be influenced by the parental origin of the retained X chromosome.

Methods

DNA samples were collected from peripheral lymphocytes of 48 women with non-mosaic 45,X karyotype and from buccal swab of their biological parents' cheek. Subsequently, the single normal X-chromosome origin was identified. Based on genetic evaluation, patients were divided into two subgroups according to the parenteral original of X chromosome - maternal (XM), and paternal (XP). Complete cardiovascular examination (echocardiography, MRI of the heart and great vessels) was performed in each of our study patient. Differences between the prevalence of BAV and CoA in two above mentioned subgroups were tested by Student's t-test using R Statistical Software version 2.15.3.

Results

The origin of the single X chromosome was as follows: in 14 (29.2%) individuals was proved paternal and in 34 (70.8%) maternal origin of X chromosome. The prevalence of BAV in the whole group was 47.9%, in XP 58%, in XM 44.1%; the prevalence of CoA in the whole group was 8.3%, in XP 7.1%, in XM 8.8%. There was no statistically significant difference identified between the prevalence of BAV and CoA in XP and XM subgroups.

Conclusions

Our study confirmed an extremely high prevalence of BAV and CoA in non-mosaic women with X chromosome monosomy but no clear evidence for X-linked genomic imprinting effect on the CoA and BAV development in TS individuals was found. However, further studies of larger numbers of TS patients are crucial to finally clarify the real relationship of genomic imprinting and cardiovascular disease in TS.

Funding Acknowledgement

Type of funding source: Public grant(s) – National budget only. Main funding source(s): Supported by the grant from Ministry of Health of the Czech Republic VES 2017

Quality of Life and Treatment Satisfaction in Participants with Maturity-Onset Diabetes of the Young: A Comparison to Other Major Forms of Diabetes

AIMS

We investigated the quality of life (QoL), treatment satisfaction and perception of genetic results in participants with Maturity-Onset Diabetes of the Young (MODY) and compared the results with those of subjects with type 1 (T1D) or type 2 (T2D) diabetes.

METHODS

A total of 162 adults with GCK-MODY, 62 with HNF1A-MODY and 29 with HNF4A-MODY answered the questionnaire Audit of Diabetes Dependent Quality of Life, the Diabetes Treatment Satisfaction Questionnaire and non-validated instrument examining the respondent's perception of the genetic results. Data from GCK-MODY patients were compared with 84 participants with T2D and HNF-MODY subjects were compared with 81 participants having T1D.

RESULTS

Higher age (p=0.004), higher haemoglobin A1c (p=0.026) and medication (p=0.019) were associated with lower general QoL in GCK-MODY patients. In HNF-MODY patients, lower general QoL was associated with a longer time since diagnosis (p=0.005), worse haemoglobin bA1c (p=0.006) and insulin treatment (p=0.019). Similar numbers of participants with GCK- and HNF-MODY considered the genetic diagnosis of MODY to be positive, negative and without significance. The patient with GCK-MODY did not differ from those with T2D in terms of their QoL, but they were less satisfied with their treatment (p<0.001). QoL was better in patients with HNF-MODY compared with patients with T1D (p=0.006), and they did not differ in terms of treatment satisfaction.

CONCLUSIONS

QoL was affected in both GCK-MODY and HNF-MODY subjects. Apprehension of genetic diagnosis was not single-valued in MODY respondents.

Disease characteristics of MCT8 deficiency: an international, retrospective, multicentre cohort study

BACKGROUND

Disordered thyroid hormone transport, due to mutations in the SLC16A2 gene encoding monocarboxylate transporter 8 (MCT8), is characterised by intellectual and motor disability resulting from cerebral hypothyroidism and chronic peripheral thyrotoxicosis. We sought to systematically assess the phenotypic characteristics and natural history of patients with MCT8 deficiency.

METHODS

We did an international, multicentre, cohort study, analysing retrospective data from Jan 1, 2003, to Dec 31, 2019, from patients with MCT8 deficiency followed up in 47 hospitals in 22 countries globally. The key inclusion criterion was genetically confirmed MCT8 deficiency. There were no exclusion criteria. Our primary objective was to analyse the overall survival of patients with MCT8 deficiency and document causes of death. We also compared survival between patients who did or did not attain full head control by age 1·5 years and between patients who were or were not underweight by age 1-3 years (defined as a bodyweight-for-age Z score <-2 SDs or <5th percentile according to WHO definition). Other objectives were to assess neurocognitive function and outcomes, and clinical parameters including anthropometric characteristics, biochemical markers, and neuroimaging findings.

FINDINGS

Between Oct 14, 2014, and Jan 17, 2020, we enrolled 151 patients with 73 different MCT8 (SLC16A2) mutations. Median age at diagnosis was 24·0 months (IQR 12·0-60·0, range 0·0-744·0). 32 (21%) of 151 patients died; the main causes of mortality in these patients were pulmonary infection (six [19%]) and sudden death (six [19%]). Median overall survival was 35·0 years (95% CI 8·3-61·7). Individuals who did not attain head control by age 1·5 years had an increased risk of death compared with patients who did attain head control (hazard ratio [HR] 3·46, 95% CI 1·76-8·34; log-rank test p=0·0041). Patients who were underweight during age 1-3 years had an increased risk for death compared with patients who were of normal bodyweight at this age (HR 4·71, 95% CI 1·26-17·58, p=0·021). The few motor and cognitive abilities of patients did not improve with age, as evidenced by the absence of significant correlations between biological age and scores on the Gross Motor Function Measure-88 and Bayley Scales of Infant Development III. Tri-iodothyronine concentrations were above the age-specific upper limit in 96 (95%) of 101 patients and free thyroxine concentrations were below the age-specific lower limit in 94 (89%) of 106 patients. 59 (71%) of 83 patients were underweight. 25 (53%) of 47 patients had elevated systolic blood pressure above the 90th percentile, 34 (76%) of 45 patients had premature atrial contractions, and 20 (31%) of 64 had resting tachycardia. The most consistent MRI finding was a global delay in myelination, which occurred in 13 (100%) of 13 patients.

INTERPRETATION

Our description of characteristics of MCT8 deficiency in a large patient cohort reveals poor survival with a high prevalence of treatable underlying risk factors, and provides knowledge that might inform clinical management and future evaluation of therapies.

FUNDING

Netherlands Organisation for Health Research and Development, and the Sherman Foundation.

NPR2 Variants Are Frequent among Children with Familiar Short Stature and Respond Well to Growth Hormone Therapy

CONTEXT

The C-type natriuretic peptide receptor encoded by the NPR2 gene is a paracrine regulator of the growth plate; heterozygous NPR2 variants cause short stature with possible presence of different signs of bone dysplasia. To date, the effect of growth hormone (GH) treatment has been described in a few individuals with NPR2 gene variants with inconsistent results.

OBJECTIVES

To identify NPR2 gene variants among children with familial short stature (FSS) and to describe their phenotype, including GH treatment response.

DESIGN, SETTINGS AND PATIENTS

Out of 747 patients with short stature treated with GH in a single center, 87 with FSS met the inclusion criteria (pretreatment height ≤ -2 standard deviation in both the patient and the shorter parent, unknown genetic etiology). Next-generation sequencing methods were performed to search for NPR2 gene variants. The results were evaluated using the American College of Medical Genetics and Genomics guidelines. The GH treatment response (growth velocity improvement and height standard deviation score development over the first 5 years of treatment) was evaluated.

RESULTS

In 5/87 children (5.7%), a (likely) pathogenic variant in the NPR2 gene was identified (p.Ile558Thr [in 2], p.Arg205*, p.Arg557His, p.Ser603Thr). Two children had disproportionate short-limbed short stature, 1 a dysplastic 5th finger phalanx. The growth velocity in the first year of GH treatment accelerated by 3.6 to 4.2 cm/year; the height improved by 1.2 to 1.8 SD over 5 years of treatment.

CONCLUSIONS

NPR2 gene variants cause FSS in a significant proportion of children. Their GH treatment response is promising. Studies including final height data are necessary to assess the long-term efficacy of this therapy.

Primary School Performance of Girls with Turner Syndrome: A Transcultural Assessment

OBJECTIVES

We analyzed primary school performance of girls with Turner syndrome (TS) in two distinct countries to ascertain if the cognitive phenotype of TS causes selective learning difficulties.

METHODS

The cohort comprised of 44 Czech and 50 Egyptian girls with TS who attended public schools. School reports from grades 1 to 9 were obtained retrospectively from Czech participants with TS. Only recent school reports were obtained from Egyptian participants. Two controls per participant were requested - biological sisters and/or female classmates. The results were converted into a 5-point scale (1-excellent; 5-unsatisfactory).

RESULTS

Analysis of longitudinal Czech data displayed a strong time component in both subjects and controls. Showing better points in lower grades with its gradual worsening as the education complexity increased. In contrast, there was a strong statistically significant difference between groups in Mathematics (p=0.0041, p=0.0205 after Bonferroni correction) and this difference increased over time. The points for Mathematics did not differ in grades 1+2 (0.05 difference in mean grade between the two groups), however, they differed by 0.28 in grades 6+7 and by 0.32 in grades 8+9. While slightly different in character (cross-sectional vs. longitudinal), the Egyptian cohort data confirmed our findings, showing no difference in general school performance but having similar trends in Mathematics (grades 1+2: 0.11, grades 6+7: 0.54, grades 8+9: 0.68; p=0.0058, p=0.029 after Bonferroni correction).

CONCLUSION

Excluding results in Mathematics, which showed pronounced worsening in relation to age in comparison with unaffected controls, girls with TS performed similarly to their controls.

Screening of monogenic autoimmune diabetes among children with type 1 diabetes and multiple autoimmune diseases: is it worth doing?

Background Paediatric type 1 diabetes (T1D) and rare syndromes of monogenic multi-organ autoimmunity share basic features such as full insulin dependency and the presence of circulating beta-cell autoantibodies. However, the aetiopathogenesis, natural course and treatment of these conditions differ; therefore, monogenic multi-organ autoimmunity requires early recognition. We aimed to search for these monogenic conditions among a large cohort of children with T1D. Methods Of 519 children with T1D followed-up in a single centre, 18 had multiple additional autoimmune conditions - either autoimmune thyroid disease (AITD) and coeliac disease (CD) or at least one additional organ-specific autoimmune condition in addition to AITD or CD. These 18 children were tested by direct Sanger sequencing (four patients with a suggestive phenotype of immune dysregulation, polyendocrinopathy, enteropathy, X-linked [IPEX] or signal transducer and activator of transcription 3 [STAT3]- and cytotoxic T-lymphocyte protein 4 [CTLA4]-associated syndromes) or by whole-exome sequencing (WES) focused on autoimmune regulator (AIRE), forkhead box protein 3 (FOXP3), CTLA4, STAT3, signal transducer and activator of transcription 1 (STAT1), lipopolysaccharide-responsive and beige-like anchor protein (LRBA) and interleukin-2 receptor subunit α (IL2RA) genes. In addition, we assessed their T1D genetic risk score (T1D-GRS). Results We identified novel variants in FOXP3, STAT3 and CTLA4 in four cases. All patients had a severe phenotype suggestive of a single gene defect. No variants were identified in the remaining 14 patients. T1D-GRS varied among the entire cohort; four patients had scores below the 25th centile including two genetically confirmed cases. Conclusions A monogenic cause of autoimmune diabetes was confirmed only in four patients. Genetic screening for monogenic autoimmunity in children with a milder phenotype and a combination of AITD and CD is unlikely to identify a monogenic cause. In addition, the T1D-GRS varied among individual T1D patients.

High Prevalence of Growth Plate Gene Variants in Children With Familial Short Stature Treated With GH

CONTEXT

Familial short stature (FSS) is a term describing a growth disorder that is vertically transmitted. Milder forms may result from the combined effect of multiple genes; more severe short stature is suggestive of a monogenic condition. The etiology of most FSS cases has not been thoroughly elucidated to date.

OBJECTIVES

To identify the genetic etiology of severe FSS in children treated with GH because of the diagnosis of small for gestational age or GH deficiency (SGA/GHD).

DESIGN, SETTINGS, AND PATIENTS

Of 736 children treated with GH because of GHD/SGA, 33 with severe FSS (life-minimum height -2.5 SD or less in both the patient and shorter parent) were included in the study. The genetic etiology was known in 5 of 33 children prior to the study [ACAN (in 2], NF1, PTPN11, and SOS1). In the remaining 28 of 33, whole-exome sequencing was performed. The results were evaluated using American College of Medical Genetics and Genomics standards and guidelines.

RESULTS

In 30 of 33 children (90%), we found at least one variant with potential clinical significance in genes known to affect growth. A genetic cause was elucidated in 17 of 33 (52%). Of these children, variants in growth plate-related genes were found in 9 of 17 [COL2A1, COL11A1, and ACAN (all in 2), FLNB, FGFR3, and IGF1R], and IGF-associated proteins were affected in 2 of 17 (IGFALS and HMGA2). In the remaining 6 of 17, the discovered genetic mechanisms were miscellaneous (TRHR, MBTPS2, GHSR, NF1, PTPN11, and SOS1).

CONCLUSIONS

Single-gene variants are frequent among families with severe FSS, with variants affecting the growth plate being the most prevalent.

Effectiveness and safety of the tri-iodothyronine analogue Triac in children and adults with MCT8 deficiency: an international, single-arm, open-label, phase 2 trial

BACKGROUND

Deficiency of the thyroid hormone transporter monocarboxylate transporter 8 (MCT8) causes severe intellectual and motor disability and high serum tri-iodothyronine (T₃) concentrations (Allan-Herndon-Dudley syndrome). This chronic thyrotoxicosis leads to progressive deterioration in bodyweight, tachycardia, and muscle wasting, predisposing affected individuals to substantial morbidity and mortality. Treatment that safely alleviates peripheral thyrotoxicosis and reverses cerebral hypothyroidism is not yet available. We aimed to investigate the effects of treatment with the T₃ analogue Triac (3,3',5-tri-iodothyroacetic acid, or tiratricol), in patients with MCT8 deficiency.

METHODS

In this investigator-initiated, multicentre, open-label, single-arm, phase 2, pragmatic trial, we investigated the effectiveness and safety of oral Triac in male paediatric and adult patients with MCT8 deficiency in eight countries in Europe and one site in South Africa. Triac was administered in a predefined escalating dose schedule-after the initial dose of once-daily 350 μg Triac, the daily dose was increased progressively in 350 μg increments, with the goal of attaining serum total T₃ concentrations within the target range of 1·4-2·5 nmol/L. We assessed changes in several clinical and biochemical signs of hyperthyroidism between baseline and 12 months of treatment. The prespecified primary endpoint was the change in serum T₃ concentrations from baseline to month 12. The co-primary endpoints were changes in concentrations of serum thyroid-stimulating hormone (TSH), free and total thyroxine (T₄), and total reverse T₃ from baseline to month 12. These analyses were done in patients who received at least one dose of Triac and had at least one post-baseline evaluation of serum throid function. This trial is registered with ClinicalTrials.gov, number NCT02060474.

FINDINGS

Between Oct 15, 2014, and June 1, 2017, we screened 50 patients, all of whom were eligible. Of these patients, four (8%) patients decided not to participate because of travel commitments. 46 (92%) patients were therefore enrolled in the trial to receive Triac (median age 7·1 years [range 0·8-66·8]). 45 (98%) participants received Triac and had at least one follow-up measurement of thyroid function and thus were included in the analyses of the primary endpoints. Of these 45 patients, five did not complete the trial (two patients withdrew [travel burden, severe pre-existing comorbidity], one was lost to follow-up, one developed of Graves disease, and one died of sepsis). Patients required a mean dose of 38.3 μg/kg of bodyweight (range 6·4-84·3) to attain T₃ concentrations within the target range. Serum T₃ concentration decreased from 4·97 nmol/L (SD 1·55) at baseline to 1·82 nmol/L (0·69) at month 12 (mean decrease 3·15 nmol/L, 95% CI 2·68-3·62; p<0·0001), while serum TSH concentrations decreased from 2·91 mU/L (SD 1·68) to 1·02 mU/L (1·14; mean decrease 1·89 mU/L, 1·39-2·39; p<0·0001) and serum free T₄ concentrations decreased from 9·5 pmol/L (SD 2·5) to 3·4 (1·6; mean decrease 6·1 pmol/L (5·4-6·8; p<0·0001). Additionally, serum total T₄ concentrations decreased by 31·6 nmol/L (28·0-35·2; p<0·0001) and reverse T₃ by 0·08 nmol/L (0·05-0·10; p<0·0001). Seven treatment-related adverse events (transiently increased perspiration or irritability) occurred in six (13%) patients. 26 serious adverse events that were considered unrelated to treatment occurred in 18 (39%) patients (mostly hospital admissions because of infections). One patient died from pulmonary sepsis leading to multi-organ failure, which was unrelated to Triac treatment.

INTERPRETATION

Key features of peripheral thyrotoxicosis were alleviated in paediatric and adult patients with MCT8 deficiency who were treated with Triac. Triac seems a reasonable treatment strategy to ameliorate the consequences of untreated peripheral thyrotoxicosis in patients with MCT8 deficiency.

FUNDING

Dutch Scientific Organization, Sherman Foundation, NeMO Foundation, Wellcome Trust, UK National Institute for Health Research Cambridge Biomedical Centre, Toulouse University Hospital, and Una Vita Rara ONLUS.

Short stature in a boy with atypical progeria syndrome due to LMNA c.433G>A [p.(Glu145Lys)]: apparent growth hormone deficiency but poor response to growth hormone therapy

Background Hutchinson-Gilford progeria syndrome (HGPS) is a rare disease caused by pathogenic variants in the LMNA gene, which leads to premature aging. The median life expectancy is shortened to 13 years due to cardiovascular complications. Case report We present a boy born with a pathogenic LMNA variant c.433G > A, which causes atypical progeria syndrome (APS) and was previously described in one single patient. When investigated for poor growth prior to the diagnosis of APS, his laboratory tests revealed growth hormone (GH) deficiency and magnetic resonance imaging (MRI) of the midbrain showed partial empty sella. GH treatment had only a limited and transient effect. His first ischemic complication manifested at age 4.2 years; at the age of 7 years, he had a fatal haemorrhagic stroke. Conclusion To the best of our knowledge, this is the first patient with APS showing partial empty sella and GH deficiency that might have contributed to his poor growth. GH failed to improve long-term outcome.

For Debate: The Significance of Etiologic Diagnosis in Neonates with Overgrowth Syndromes. Lesson Learned from the Simpson-Golabi-Behmel Syndrome

Overgrowth syndromes are rare genetic disorders characterized by excessive pre- and postnatal growth accompanied by dysmorphic features and developmental disorders. In addition to other health hazards, the life expectancy of affected children may be compromised due to an increased risk of developing tumors. To demonstrate the need for early recognition, correct diagnostic evaluation and adequate follow-up, we present a family with recurrent Simpson-Golabi-Behmel syndrome (SGBS). SGBS is a X-linked neonatal overgrowth syndrome caused by mutations in the GPC3 or GPC4 genes. All three affected males manifested with congenital diaphragmatic hernia. When fetal overgrowth and congenital diaphragmatic hernia co-occur, the choice for a possible cause is limited among SGBS, Marfan syndrome and Pallister-Killian syndrome. Their different phenotypes allow clinical assessment and correct diagnosis in most cases and should be followed by genetic testing. Regular oncologic screening aimed towards early recognition of malignant tumors may improve long-term outcomes in SGBS as well as in all other overgrowth syndromes.

An isolated Xp deletion is linked to autoimmune diseases in Turner syndrome

Background Females with Turner syndrome (TS) are prone to develop autoimmune diseases (AIDs). The X chromosome contains several immune-related genes. Growth hormone (GH) and estrogens modulate the immune system. We aimed to clarify whether the loss of a specific X chromosome gene locus and the administration of GH and estradiol facilitate the development of AIDs in TS females. Methods Retrospective data on clinical course, AIDs, karyotype and treatment were analyzed from a cohort of 286 Czech females with TS (current age 2.8-43.3 years; median age 18.7 years). The karyotypes were sorted using two different classification systems: a mosaicism-focused and an isochromosome (isoXq)-focused approach. Karyotype subgroups with a significantly higher prevalence of AIDs were further evaluated. Data of common therapies were correlated with the prevalence of AIDs. Results The most frequent AIDs were autoimmune thyroid disease (AITD; 37.4%; n = 107) and celiac disease (CD; 8.7%; n = 25). All karyotype subgroups were prone to develop AIDs. Females with an isolated Xp deletion had a significantly higher prevalence of AITD and CD compared to all other individuals with TS (AITD: 66.0% vs. 31.5%, p < 0.0001; CD: 17.4% vs. 7.2%; p = 0.04, respectively). We observed no link between the mean age at initiation as well as the duration of GH and/or estrogen administration and the occurrence of AIDs. Conclusions Isolated Xp deletion contributes to the development of AIDs in TS patients. The haploinsufficiency of genes located in Xpter-p11.2 may explain this observation. Common therapies used in TS do not modify the risk of AIDs.

The bacteriome at the onset of type 1 diabetes: A study from four geographically distant African and Asian countries

OBJECTIVES

Gut bacteriome profiling studies in type 1 diabetes (T1D) to date are mostly limited to populations of Europe, with two studies from China and one study each from Mexico and the USA. We therefore sought to characterize the stool bacteriome in children after onset of T1D along with age- and place-matched control subjects from four geographically distant African and Asian countries.

METHODS

Samples were collected from 73 children and adolescents shortly after T1D onset (Azerbaijan 19, Jordan 20, Nigeria 14, Sudan 20) and 104 matched control subjects of similar age and locale. Genotyping of major T1D susceptibility genes was performed using saliva or blood samples. The bacteriome was profiled by next-generation sequencing of 16S rDNA. Negative binomial regression was used to model associations, with adjustment for the matched structure of the study.

RESULTS

A significant positive association with T1D was noted for the genus Escherichia (class Gammaproteobacteria, phylum Proteobacteria), whereas Eubacterium and Roseburia, two genera of class Clostridia, phylum Firmicutes, were inversely associated with T1D. We also confirmed a previously observed inverse association with Clostridium clusters IV or XIVa. No associations were noted for richness, evenness, or enterotypes.

CONCLUSIONS

Based on our results, some type of distortion of the gut bacteriome appears to be a global feature of T1D, and our findings for four distant populations add new candidates to the existing list of bacteria. It remains to be established whether the observed associations are markers or causative factors.

Short Stature in a Boy with Multiple Early-Onset Autoimmune Conditions due to a STAT3 Activating Mutation: Could Intracellular Growth Hormone Signalling Be Compromised?

BACKGROUND

Germline STAT3 gain-of-function (GOF) mutations cause multiple endocrine and haematologic autoimmune disorders, lymphoproliferation, and growth impairment. As the JAK-STAT pathway is known to transduce the growth hormone (GH) signalling, and STAT3 interacts with STAT5 in growth regulation, we hypothesised that short stature in STAT3 GOF mutations results mostly from GH insensitivity via involving activation of STAT5.

CASE REPORT

A boy with a novel STAT3 c.2144C>T (p.Pro715Leu) mutation presented with short stature (-2.60 SD at 5.5 years). He developed diabetes mellitus at 11 months, generalised lympho-proliferation, autoimmune thyroid disease, and immune bicytopenia in the subsequent years. At 5.5 years, his insulin-like growth factor-1 (IGF-I) was 37 µg/L (-2.22 SD) but stimulated GH was 27.7 µg/L. Both a standard IGF-I generation test (GH 0.033 mg/kg/day sc; 4 days) and a high-dose prolonged IGF-I generation test (GH 0.067 mg/kg/day sc; 14 days) failed to significantly increase IGF-I levels (37-46 and 72-87 µg/L, respectively). The boy underwent haematopoietic stem cell transplantation at 6 years due to severe neutropenia and massive lymphoproliferation, but unfortunately deceased 42 days after transplantation from reactivated generalised adenoviral infection.

CONCLUSIONS

Our findings confirm the effect of STAT3 GOF mutation on the downstream activation of STAT5 resulting in partial GH insensitivity. 
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A 6-Year Follow-Up of Fracture Incidence and Volumetric Bone Mineral Density Development in Girls With Turner Syndrome

CONTEXT

Patients with Turner syndrome (TS) are at risk for osteoporotic fractures.

OBJECTIVE

The aims of this study were to assess the incidence of clinically important fractures in girls with TS and prospectively describe the development of volumetric bone mineral density (BMD).

DESIGN

Peripheral quantitative computerized tomography (pQCT) of the radius every other year over the 6 years of observation.

SETTING

Government-funded university referral center.

PARTICIPANTS

Thirty-two girls with TS, aged 6 to 16 years, were included in the analyses. Fracture incidence was compared with the data in the general population. Bone density and strength were compared with data from 185 healthy girls.

OUTCOMES

The main clinical outcome was the fracture occurrence. The secondary outcomes were the changes in Z-scores of the bone parameters.

RESULTS

Three girls with TS sustained four fractures during 6 years of observation. The fracture rate in TS was not substantially higher than the downward-biased fracture-rate estimate from age-matched, healthy controls (P = 0.48). Whereas the trabecular BMD Z-score decreased with age (β estimate -0.21 ± 0.04, P < 0.001), total bone cross-sectional area correspondingly increased (+0.16 ± 0.04, P < 0.001), which led to normal bone strength. A positive history of incident fractures was not significantly associated with any of the pQCT-derived bone parameters.

CONCLUSIONS

Current pediatric TS patients that are treated with growth hormone and estrogens are not at risk for osteoporotic fractures. Low BMD in TS may be counterweighted by enlarged bone radius, which leads to normal bone strength at the appendicular skeleton.

For Debate: Should Bariatric Surgery be Performed in Children and Adolescents with Hypothalamic Obesity?

Hypothalamic dysfunction leading to severe obesity is a serious long-term consequence of paediatric craniopharyngioma. It compromises quality of life, leads to long-term metabolic hazards, and may shorten life expectancy. Therefore, a proactive approach is required. Conventional treatment of hypothalamic obesity is difficult and hardly successful. Experience with bariatric surgery is limited, especially in younger patients. Two retrospective studies recently reported on classic bariatric surgery in a small series of individuals after craniopharyngioma. Of these, one included nine paediatric patients who underwent laparoscopic adjustable gastric banding (LAGB), sleeve gastrectomy (SG), Roux-en-Y gastric bypass (RYGB) or biliopancreatic diversion (BPD). The immediate effects were promising: The mean weight loss was 20.9 kilograms at 6 months and 15.1 kilograms at 12 months. A duodenal-jejunal bypass sleeve (DBJS; EndoBarrier) is a mini-invasive, endoscopically placed and fully reversible bariatric procedure. We reported a boy diagnosed with craniopharyngioma at 10 years old who underwent surgery and radiotherapy. His body weight increased to 139 kilograms and body mass index (BMI) to 46.1 kg/m2 (+4.0 SD) within the subsequent 4.5 years. Fifteen months after DJBS placement, he lost 32.8 kilograms, and his BMI dropped to 32.7 kg/m2 (+2.9 SD). Thus, DJBS proved to be a promising procedure in the treatment of hypothalamic obesity. We suggest performing it in children and adolescents with hypothalamic obesity to prevent or attenuate its devastating long-term sequelae.

Could a combination of heterozygous ABCC8 and KCNJ11 mutations cause congenital hyperinsulinism?

BACKGROUND

Congenital hyperinsulinism (CHI) is frequently caused by mutations in one of the KATP channel subunits encoded by the genes ABCC8 and KCNJ11. The effect of simultaneous mutations in both of these genes on the pancreatic β-cell function is not known and patients with CHI carrying both ABCC8 and KCNJ11 mutations have not yet been reported. We questioned if a combination of heterozygous mutations in the ABCC8 and KCNJ11 genes could also lead to β-cell dysfunction presenting as CHI.

METHODS

As a model, we used a patient with transient CHI that paternally inherited novel heterozygous mutations in ABCC8 (p.Tyr1293Asp) and KCNJ11 (p.Arg50Trp) genes. The pathogenic effects on the pancreatic β-cells function were examined in an in vitro functional study using radioactive rubidium efflux assay.

RESULTS

We showed that the activation of the mutated KATP channels by diazoxide was decreased by 60.9% in the channels with the heterozygous combination of both mutations compared to the wild type channels. This could indicate the pathogenic effect on the pancreatic β-cell function leading to CHI although conclusive evidence is needed to be added.

CONCLUSIONS

Our findings may widen the spectrum of genetic causes of CHI and suggest a novel pathogenic mechanism of CHI that must however, be further investigated.

MODY in Ukraine: genes, clinical phenotypes and treatment

BACKGROUND

Maturity-onset diabetes of the young (MODY) has not been previously studied in Ukraine. We investigated the genetic etiology in a selected cohort of patients with diabetes diagnosed before 18 years of age, and in their family members.

METHODS

Genetic testing of the most prevalent MODY genes (GCK, HNF1A, HNF4A, HNF1B and INS) was undertaken for 36 families (39 affected individuals) by Sanger or targeted next generation sequencing.

RESULTS

A genetic diagnosis of MODY was made in 15/39 affected individuals from 12/36 families (33%). HNF1A and HNF4A MODY were the most common subtypes, accounting for 9/15 of MODY cases. Eight patients with HNF1A or HNF4A MODY and inadequate glycemic control were successfully transferred to sulfonylureas. Median HbA1c decreased from 67 mmol/mol (range 58-69) to 47 mmol/mol (range 43-50) (8.3% [7.5-8.5] to 6.4% [6.1-6.7]) 3 months after transfer (p=0.006).

CONCLUSIONS

Genetic testing identified pathogenic HNF1A and HNF4A variants as the most common cause of MODY in Ukraine. Transfer to sulfonylureas substantially improved the glycemic control of these patients.