Choledochal Cyst with 17q12 Chromosomal Duplication

The 17q12 chromosomal region carries the HNF1B gene, mutations of which cause various conditions. When searching for HNF1B/17q12 rearrangements among children with biliary atresia and/or choledochal cysts, we identified a male proband carrying a 17q12 duplication spanning 1698 kb that included 24 genes from TBC1D3C to HNF1B. The boy presented with cholestatic jaundice at the age of 2 weeks due to a choledochal cyst sized 15 ×12 mm (type Ia according to the Todani classification). He underwent a shunt surgery consisting of a hepaticojejunostomy using Roux-en-Y loop at the age of 2 months, which led to a permanent relief of cholestasis. Perioperative liver histology revealed significant hepatic fibrosis and bile ductular proliferation. At 17 years, he has a mildly enlarged liver with decreased elasticity, an upper-normal-sized spleen, normal biochemistry values, and no renal or hepatic cysts. We report the first hepatobiliary phenotype in a patient with an HNF1B overdosage.

Novel glucokinase gene mutation in the first Macedonian family tested for MODY

We present a boy with mild hyperglycemia detected during an upper respiratory infection. Novel splicing mutation in the intron 1 of the GCK gene (c.45+1G>A) was detected, and was subsequently confirmed in his father. This is the first case of genetically confirmed Macedonian family with MODY.

Glucokinase Gene May Be a More Suitable Target Than the Insulin Gene for Detection of β Cell Death

Detection and quantification of unmethylated circulating insulin (INS) DNA presumably released from β cells has been previously used for assessing their destruction. As the targets within the INS gene suffer from suboptimal specificity, we sought to improve the assay parameters by using the glucokinase gene (GCK) tissue-specific pancreatic promoter. The amount of methylated and unmethylated GCK DNA was measured using a droplet polymerase chain reaction assay and compared with the previously published INS-targeted assay. The method was tested using synthetic target sequences and DNA from pancreatic islets, blood, brain, kidney, large intestine, liver, lung, small intestine, and stomach. Circulating serum DNA was obtained from children with recent-onset type 1 diabetes (T1D) (n = 25), autoantibody-positive first-degree relatives of T1D patients (n = 14), and healthy controls (n = 20). The unmethylated GCK DNA was found to be more islet specific than unmethylated INS DNA. The proportion of the unmethylated GCK DNA was lower than INS in all tested extrapancreatic tissues, except kidney. Although the amounts of methylated DNA measured by the two assays were similar, the INS assay detected considerably more unmethylated DNA. Whereas none of the assays showed significant increase in the amount of unmethylated DNA, the ratio of unmethylated/methylated GCK DNA was borderline significantly increased in autoantibody-positive relatives compared with T1D patients (P = 0.04) and controls (P = 0.06). Targeting the assay into the GCK gene improved analytical parameters of the assay. As the amount of unmethylated target DNA in properly treated samples is very low, the clinical utility of this method remains to be evaluated.

A Rare Variant of Turner Syndrome in Four Sequential Generations: Effect of the Interplay of Growth Hormone Treatment and Estrogens on Body Proportion

BACKGROUND

Terminal Xp deletion leads to SHOX haploinsufficiency, and when it exceeds Xp22.33 it causes a variant of Turner syndrome (TS) in which gonadal function is preserved and short stature constitutes the major clinical feature.

CASE REPORT

We present a family with vertical transmission of TS that affected six women in four sequential generations. The karyotype was defined as a combination of terminal Xp deletion and terminal Xq duplication: 46,X,rec(X)inv(p21.1q27.3). All affected women had short stature, but had developed spontaneous puberty and normal fertility. Generation IV exclusively received recombinant human growth hormone (rhGH). We investigated the effect of rhGH treatment on skeletal growth and body proportion via the comparison of auxological data from an untreated 39.7-year-old mother to her 14.8-year-old rhGH-treated daughter. The adult height of the daughter was substantially better than that of the mother [160.3 cm (-0.8 SDS) and 150.0 cm (-2.7 SDS), respectively]; however, the disproportion progressed following rhGH treatment and ultimately led to a worse trunk-to-extremities ratio compared with the mother (4.8 and 3.7 SDS, respectively).

CONCLUSION

This rare family confirms the vertical transmission of TS spanning multiple generations. The combination of endogenous estrogen production and exogenous rhGH administration in women with SHOX haploinsufficiency may worsen their body disproportion.

Alteration of B cell subsets and the receptor for B cell activating factor (BAFF) in paediatric patients with type 1 diabetes

BACKGROUND

Lately, mounting evidence has shown that B cells play an important role in the pathogenesis of type 1 diabetes (T1D). Here, we present alterations in B cell subsets including BAFF receptor (BAFFR) expression in cohorts of patients with type 1 diabetes (T1D) and their relatives.

PATIENTS AND METHODS

B cells were studied in 438 patients with T1D (158 at disease onset and 280 with long-term disease), 136 first-degree relatives and 53 healthy controls. The B cell panel included transitional, naïve, MZ-like, switched memory B cells and plasmablasts. We also measured serum BAFF levels as well as BAFFR expression on both B and T cells. Moreover, the effect of BAFF on T and B lymphocytes was analysed in vitro.

RESULTS

We observed a significant decrease in the proportion of transitional B cells in the patients with T1D, accompanied by an increased proportion of plasmablasts, especially in recent-onset patients and their relatives. While the BAFF serum levels did not differ in the patients with T1D, BAFFR-expressing B and especially T cell numbers were reduced in the T1D cohort, with the exception of patients with recent-onset disease who exhibited a significant increase in the number of BAFFR-expressing T cells. T cell activation and B cell proliferation were more pronounced after activation with BAFF in the T1D cohort compared to controls.

CONCLUSION

The B cell panel in patients with T1D is characterized by significantly reduced populations of B cells in their early stages of development with a shift towards plasma cells. The dynamics of BAFFR-expressing B and T cells and the more pronounced responsiveness of the T1D T cells to BAFF point to the role of BAFF and T and B cell cooperation in the development of T1D.

Increased prevalence of bicuspid aortic valve in Turner syndrome links with karyotype: the crucial importance of detailed cardiovascular screening

BACKGROUND

Bicuspid aortic valve (BAV) represents one of the strongest risk factors for aortic dissection in Turner syndrome (TS). An exact relation between the occurrence of BAV and a particular karyotype has not been established yet. The aim of this study was to determine the association between karyotype and prevalence of BAV.

METHODS

Sixty-seven TS patients aged between 6.6 and 32.5 years underwent cardiac magnetic resonance imaging (MRI) study. They were divided into four cytogenetic subgroups-45,X karyotype (n=27); 45,X/46,XX mosaicism (n=17); structural abnormalities of the X chromosome (n=10); and 45,X/structural abnormality of the X chromosome mosaicism (n=13). Prevalence of BAV and odds ratio (OR) compared with the general population in the whole study group, and statistical comparison of prevalences of BAV among the individual subgroups were determined.

RESULTS

Prevalence of BAV in the whole study group was established as 28.4% [OR 208.3 (95% CI - 103.8-418.0); p-value<0.0001]. Individuals with 45,X karyotype had the highest prevalence of BAV - 40.7%, p-value<0.0001. Presence of any 45,X cell line in karyotype significantly predisposed to BAV (p-value=0.05).

CONCLUSIONS

The 45,X karyotype is associated with the highest prevalence of BAV. Also, the presence of the 45,X cell line in any mosaic karyotype increases the probability of BAV.

Clinical Characterization of Patients With Autosomal Dominant Short Stature due to Aggrecan Mutations

CONTEXT

Heterozygous mutations in the aggrecan gene (ACAN) cause autosomal dominant short stature with accelerated skeletal maturation.

OBJECTIVE

We sought to characterize the phenotypic spectrum and response to growth-promoting therapies.

PATIENTS AND METHODS

One hundred three individuals (57 females, 46 males) from 20 families with autosomal dominant short stature and heterozygous ACAN mutations were identified and confirmed using whole-exome sequencing, targeted next-generation sequencing, and/or Sanger sequencing. Clinical information was collected from the medical records.

RESULTS

Identified ACAN variants showed perfect cosegregation with phenotype. Adult individuals had mildly disproportionate short stature [median height, -2.8 standard deviation score (SDS); range, -5.9 to -0.9] and a history of early growth cessation. The condition was frequently associated with early-onset osteoarthritis (12 families) and intervertebral disc disease (9 families). No apparent genotype-phenotype correlation was found between the type of ACAN mutation and the presence of joint complaints. Childhood height was less affected (median height, -2.0 SDS; range, -4.2 to -0.6). Most children with ACAN mutations had advanced bone age (bone age - chronologic age; median, +1.3 years; range, +0.0 to +3.7 years). Nineteen individuals had received growth hormone therapy with some evidence of increased growth velocity.

CONCLUSIONS

Heterozygous ACAN mutations result in a phenotypic spectrum ranging from mild and proportionate short stature to a mild skeletal dysplasia with disproportionate short stature and brachydactyly. Many affected individuals developed early-onset osteoarthritis and degenerative disc disease, suggesting dysfunction of the articular cartilage and intervertebral disc cartilage. Additional studies are needed to determine the optimal treatment strategy for these patients.

[Overgrowth in children and in adults: novel clinical view, novel genes, novel phenotypes]

Novel genetic findings allow to more reliably elucidate the aetiology and pathogenesis of overgrowth syndromes in children and in adults. The relatively prevalent overgrowth syndromes in foetuses and neonates include Beckwith-Wiedemann (BWS) and Sotos syndromes; in addition, several rare conditions may occur e.g. Simpson-Golabi-Behmel and Weaver syndromes. These syndromes are not connected with overproduction of growth hormone. Their carriers are at risk of hypoglycaemia (in BWS), of congenital malformations and of childhood tumours. Targeted oncologic screening may improve the outcomes. Despite rapid growth even postnatally, the final height is mostly normal. In childhood and adolescence, the increased growth velocity results from hormonal overproduction - of precocious production of sexual hormones, hyperthyroidism, or of growth hormone overproduction due to pituitary adenoma that may lead to gigantism or acrogigantism and may be familiar (familiar isolated pituitary adenoma; FIPA). In 15-25 % of affected families, FIPA is caused by autosomal dominantly inherited mutations of AIP gene encoding a tumour suppressor protein named AIP (aryl hydrocarbon receptor-interacting protein). X-linked acrogigantism (X-LAG) is due to GPR101 gene mutations or microduplications of Xq26 chromosomal region. GPR101 encodes G-protein coupled receptor with unknown ligand. X-LAG is associated with recurrent and highly-penetrant pituitary macroadenomas. Mutations of additional at least 10 genes may lead to pituitary tumour with growth hormone overproduction. Gigantism in adults results from untreated or insufficiently treated pituitary adenoma in childhood. Some of the well-known current or past giants were found to carry pathogenic genetic variants of GPR101 or AIP.

Tolerogenic Dendritic Cells from Poorly Compensated Type 1 Diabetes Patients Have Decreased Ability To Induce Stable Antigen-Specific T Cell Hyporesponsiveness and Generation of Suppressive Regulatory T Cells

Tolerogenic dendritic cells (tolDCs) may offer an interesting intervention strategy to re-establish Ag-specific tolerance in autoimmune diseases, including type 1 diabetes (T1D). T1D results from selective destruction of insulin-producing β cells leading to hyperglycemia that, in turn, specifically affects a patient's immune system. In this study, we prepared monocyte-derived tolDCs modulated by dexamethasone and vitamin D₂ from 31 T1D patients with optimal glycemic control and 60 T1D patients with suboptimal glycemic control and assessed their tolerogenic properties in correlation with metabolic state of patients. tolDCs differentiated from both groups of patients acquired a regulatory phenotype and an anti-inflammatory profile. Interestingly, tolDCs from well-controlled patients expressed higher levels of inhibitory molecules IL-T3 and PD-L1. Additionally, glutamic acid decarboxylase (GAD)65-loaded tolDCs from well-controlled patients decreased significantly primary Th1/Th17 responses, induced stable GAD65-specific T cell hyporesponsiveness, and suppressed markedly control DC-induced GAD65-specific T cell activation compared with poorly controlled patients. The ability of tolDCs from poorly controlled patients to induce durable GAD65-specific T cell hyporesponsiveness was reversed once the control of glycemia improved. In both groups of patients, tolDCs were able to induce regulatory T cells from autologous naive CD4⁺ T cells. However, regulatory T cells from well-controlled patients had better suppressive abilities. The functionality of tolDCs was confirmed in the adoptive transfer model of NOD-SCID mice where tolDCs delayed diabetes onset. These results suggest that metabolic control of T1D affects the functional characteristics of tolDCs and subsequent effector T cell responses. Metabolic control may be relevant for refining inclusion criteria of clinical trials in the settings of T1D.

Substantial proportion of MODY among multiplex families participating in a Type 1 diabetes prediction programme

AIMS

Patients with maturity-onset diabetes of the young (MODY) might be over-represented in families with histories of Type 1 diabetes. Our aim was to re-evaluate families participating in the Czech T1D Prediction Programme (PREDIA.CZ) with at least two members affected with diabetes to assess the proportion of MODY among these families and determine its most significant clinical predictors.

METHODS

Of the 557 families followed up by the PREDIA.CZ, 53 (9.5%) had two or more family members with diabetes. One proband with diabetes from these families was chosen for direct sequencing of the GCK, HNF1A, HNF4A and INS genes. Non-parametric tests and a linear logistic regression model were used to evaluate differences between MODY and non-MODY families.

RESULTS

MODY was genetically diagnosed in 24 of the 53 families with multiple occurrences of diabetes (45%). Mutations were detected most frequently in GCK (58%), followed by HNF1A (38%) and INS (4%). MODY families were more likely to have a parent with diabetes and had a higher proportion of females with diabetes than non-MODY families. Higher age (P < 0.001), a lower level of HbA_1c (P < 0.001) at clinical onset and at least two generations affected by diabetes were the variables most predictive for probands of MODY families already presenting with diabetes.

CONCLUSIONS

A prediction programme for Type 1 diabetes would provide a useful new source of patients with MODY most likely to benefit from an accurate diagnosis. This identification has implications for patient treatment and disease prognosis.

T regulatory lymphocytes in type 1 diabetes: Impaired CD25 expression and IL-2 induced STAT5 phosphorylation in pediatric patients

T regulatory cells (Tregs) are essential for maintaining tolerance and preventing autoimmune diseases, such as type 1 diabetes (T1D). In our study, we investigated CD25 + FoxP3 + Tregs and thymic FoxP3 + Helios + Tregs in large cohorts of children with T1D at onset and with long-term T1D, and further in their relatives and healthy controls. We observed significantly decreased numbers of CD25 + FoxP3 + Tregs, but not FoxP3 + Helios + Tregs, in long-term patients compared with the control group and T1D onset. Furthermore, long-term T1D patients exhibited highly significant decrease of CD25 expression on both CD25 + FoxP3 + Tregs and FoxP3 + Helios + Tregs, independently on age or the duration of diabetes. A similar reduction of CD25 expression was also found in T1D relatives, more significant in those with positive autoantibodies. Low CD25 expression was associated with impaired signal transducer and activator of transcription 5 (STAT5) phosphorylation after IL-2 exposure. Our results show that the frequency of Tregs is altered in a large cohort of long-term T1D patients, a profound decrease in CD25 expression and altered IL-2 signaling are typical features of Tregs populations in long-term diabetic patients and their relatives.

Novel calcium-sensing receptor cytoplasmic tail deletion mutation causing autosomal dominant hypocalcemia: molecular and clinical study

OBJECTIVE

Autosomal dominant hypocalcemia (ADH) is a rare disorder caused by activating mutations of the calcium-sensing receptor (CASR). The treatment of ADH patients with 1α-hydroxylated vitamin D derivatives can cause hypercalciuria leading to nephrocalcinosis.

DESIGN AND METHODS

We studied a girl who presented with hypoparathyroidism and asymptomatic hypocalcemia at age 2.5 years. Mutations of CASR were investigated by DNA sequencing. Functional analyses of mutant and WT CASRs were done in transiently transfected human embryonic kidney (HEK293) cells.

RESULTS

The proband and her father are heterozygous for an eight-nucleotide deletion c.2703_2710delCCTTGGAG in the CASR encoding the intracellular domain of the protein. Transient expression of CASR constructs in kidney cells in vitro suggested greater cell surface expression of the mutant receptor with a left-shifted extracellular calcium dose-response curve relative to that of the WT receptor consistent with gain of function. Initial treatment of the patient with calcitriol led to increased urinary calcium excretion. Evaluation for mosaicism in the paternal grandparents of the proband was negative.

CONCLUSIONS

We describe a novel naturally occurring deletion mutation within the CASR that apparently arose de novo in the father of the ADH proband. Functional analysis suggests that the cytoplasmic tail of the CASR contains determinants that regulate the attenuation of signal transduction. Early molecular analysis of the CASR gene in patients with isolated idiopathic hypoparathyroidism is recommended because of its relevance to clinical outcome and treatment choice. In ADH patients, calcium supplementation and low-dose cholecalciferol avoids hypocalcemic symptoms without compromising renal function.

[Congenital hyperinsulinism: Loss of B-cell self-control]

Congenital hyperinsulinism is a serious blood glucose regulation defect that interferes with brain development, leading to mental retardation, neurological sequelae and secondary epilepsy and ultimately may be life-threatening. Congenital hyperinsulinism (CHI) is caused by genetic defects of regulation of insulin secretion that induce insulin oversecretion in intrauterine life and postnatally. The clinical consequence is fetal macrosomia and subsequently neonatal and infantile hypoglycaemia. The most severe form is caused by biallelic mutations of KCNJ11 and ABCC8 genes that encode both potassium channel subunits, whereas their heterozygous mutations as well as enzymatic defects (GLUD1, HADH, GCK) lead to milder presentation. HNF4A or HNF1A transcriptional factor defects lead to transient hyperinsulinism but to MODY diabetes later in life, due to biphasic beta-cell dysfunction starting as hyperfunction and developing via normal function to hypofunction. An early aetiological diagnosis and effective treatment of congenital hyperinsulinism substantially improves the outcome regarding not only survival but also neurocognitive functions.Key words: B-cell - congenital hyperinsulinism (CHI) - hypoglycaemia - insulin.

High Incidence of Heterozygous ABCC8 and HNF1A Mutations in Czech Patients With Congenital Hyperinsulinism

CONTEXT

Congenital hyperinsulinism of infancy (CHI) represents a group of heterogeneous disorders characterized by oversecretion of insulin from pancreatic β-cells causing severe hypoglycemia.

OBJECTIVE

We studied the distribution of genetic causes of CHI in a Czech population.

METHODS

Countrywide collection of patients with CHI included 40 subjects (12 females, median age of diagnosis, 1 wk [interquartile range, 1-612 wk]). We sequenced the ABCC8, KCNJ11, GLUD1, GCK, HADH, UCP2, SLC16A1, HNF4A, and HNF1A genes and investigated structural changes in the ABCC8 gene. We functionally tested novel variants in the ABCC8 gene by Rb(86+) efflux assay and novel variants in the HNF1A gene by transcriptional activation and DNA-binding tests.

RESULTS

We found causal mutations in 20 subjects (50%): 19 carried a heterozygous mutation while one patient was homozygous for mutation in the ABCC8 gene. Specifically, we detected 11 mutations (seven novel) in ABCC8, one novel mutation in KCNJ11, five mutations (two novel) in HNF1A, two novel mutations in HNF4A, and one in GCK. We showed a decrease of activation by diazoxide in mutant KATP channels with novel ABCC8 variants by 41-91% (median, 82%) compared with wild-type (WT) channels and reduced transcriptional activity of mutant HNF1A proteins (2.9% for p.Asn62Lysfs93* and 22% for p.Leu254Gln) accompanied by no DNA-binding ability compared with WT HNF1A.

CONCLUSION

We detected a higher proportion of heterozygous mutations causing CHI compared with other cohorts probably due to lack of consanguinity and inclusion of milder CHI forms. Interestingly, HNF1A gene mutations represented the second most frequent genetic cause of CHI in the Czech Republic. Based on our results we present a genetic testing strategy specific for similar populations.

Gastrointestinal Autoimmunity Associated With Loss of Central Tolerance to Enteric α-Defensins

BACKGROUND & AIMS

Autoimmune polyendocrinopathy candidiasis ectodermal dystrophy (APECED) is an autoimmune disorder characterized by chronic mucocutaneous candidiasis, hypoparathyroidism, and adrenal insufficiency, but patients also develop intestinal disorders. APECED is an autosomal recessive disorder caused by mutations in the autoimmune regulator (AIRE, which regulates immune tolerance) that allow self-reactive T cells to enter the periphery. Enteric α-defensins are antimicrobial peptides secreted by Paneth cells. Patients with APECED frequently have gastrointestinal symptoms and seroreactivity against secretory granules of Paneth cells. We investigated whether enteric α-defensins are autoantigens in humans and mice with AIRE deficiency.

METHODS

We analyzed clinical data, along with serum and stool samples and available duodenal biopsies from 50 patients with APECED collected from multiple centers in Europe. Samples were assessed for expression of defensins and other molecules by quantitative reverse transcription polymerase chain reaction and flow cytometry; levels of antibodies and other proteins were measured by immunohistochemical and immunoblot analyses. Histologic analyses were performed on biopsy samples. We used Aire(-/-) mice as a model of APECED, and studied the effects of transferring immune cells from these mice to athymic mice.

RESULTS

Enteric defensins were detected in extraintestinal tissues of patients with APECED, especially in medullary thymic epithelial cells. Some patients with APECED lacked Paneth cells and were seropositive for defensin-specific autoantibodies; the presence of autoantibodies correlated with frequent diarrhea. Aire(-/-) mice developed defensin-specific T cells. Adoptive transfer of these T cells to athymic mice resulted in T-cell infiltration of the gut, loss of Paneth cells, microbial dysbiosis, and the induction of T-helper 17 cell-mediated autoimmune responses resembling those observed in patients with APECED.

CONCLUSIONS

In patients with APECED, loss of AIRE appears to cause an autoimmune response against enteric defensins and loss of Paneth cells. Aire(-/-) mice developed defensin-specific T cells that cause intestinal defects similar to those observed in patients with APECED. These findings provide a mechanism by which loss of AIRE-mediated immune tolerance leads to intestinal disorders in patients with APECED.

McCune Albright syndrome and bilateral adrenal hyperplasia: the GNAS mutation may only be present in adrenal tissue

OBJECTIVE

Corticotropin (ACTH)-independent hypercortisolism due to bilateral adrenocortical hyperplasia (BAH) in infancy is an extremely rare condition that is often caused by McCune Albright syndrome (MAS). MAS is caused by an activating mutation of the GNAS gene which leads to increased cyclic (c) adenosine monophosphate (AMP) signaling. Most forms of BAH are linked to increased cAMP signaling. We report the case of an infant with MAS who had BAH.

METHODS

Genomic DNA fragments from blood and adrenal tissue encompassing regions (exons 8 and 9) with the hot spot activating missense GNAS mutations were amplified by classical bidirectional Sanger sequencing.

RESULTS

The infant was found to carry the most common GNAS mutation, in exon 8 (c.602G >A, p. R201H), only in her adrenocortical tissue, despite extensive skin and other findings.

CONCLUSIONS

We conclude that infants with MAS, despite absence of the GNAS activating mutation in blood, may still have significant clinical findings, including ACTH-independent hypercortisolism. Molecular confirmation of the diagnosis should be sought at the tissue level in these patients.

The muscle-bone interaction in Turner syndrome

OBJECTIVES

Turner syndrome (TS) is associated with an increased fracture rate due to reduced bone strength, which is mainly determined by skeletal muscle force. This study aimed to assess the muscle force-bone strength relationship in TS and to compare it with that of healthy controls.

METHODS

This study included 39 girls with TS and 67 healthy control girls. Maximum muscle force (Fmax) was assessed through multiple one-legged hopping with jumping mechanography. Peripheral quantitative computerized tomography assessed the bone strength index at the tibial metaphysis (BSI 4) and the polar strength-strain index at the diaphysis (SSI polar 66). The effect of TS on the muscle-bone unit was tested using multiple linear regression.

RESULTS

TS had no impact on Fmax (p=0.14); however, a negative effect on bone strength (p<0.001 for BSI 4 and p<0.01 for SSI polar 66) was observed compared with healthy controls. Bone strength was lower in the TS group (by 18%, p<0.01, for BSI 4 and by 7%, p=0.027, for SSI polar 66), even after correcting for Fmax.

CONCLUSIONS

Similar muscle force induces lower bone strength in TS compared with healthy controls, which suggests altered bone-loading sensitivity in TS.

Artificially low cortical bone mineral density in Turner syndrome is due to the partial volume effect

We aimed to show that the decrease in the cortical bone mineral density (BMD) in the radius in Turner syndrome (TS) is artificially caused by the partial volume effect. We confirmed that the partial volume effect-corrected cortical BMD is not decreased in TS compared to in the healthy controls. Other factors are responsible for the increased fracture rate in TS.

INTRODUCTION

Decreased cortical bone mineral density (BMD) has been reported in Turner syndrome (TS), using peripheral quantitative computerised tomography, and it is perceived as one of the major factors leading to increased fracture risk. We tested the hypothesis that low cortical BMD in the radius is caused artificially by the partial volume effect.

METHODS

A cross-sectional study was conducted at the university hospital referral centre between March and October 2013. Thirty-two participants with TS who consented to the study were included (mean age 15.3 ± 3.2 years). We assessed the cortical BMD in the radius as well as the tibia, where the cortex is thicker compared with the radius.

RESULTS

Whereas the cortical BMD was decreased in the radius (mean ± SD Z-score -0.6 ± 1.5, p = 0.037), it was increased in the tibia (mean Z-score 0.83 ± 1.0, p < 0.001). After correcting the cortical BMD for the partial volume effect, the mean Z-score was normal in the radius in TS (0.4 ± 1.3, p = 0.064). The corrected cortical BMD values were similar in the radius and tibia (1108 ± 52 vs. 1104 ± 48, group difference p = 0.75).

CONCLUSIONS

The cortical BMD is not decreased in TS. The partial volume effect is responsible for previous findings of decreased cortical BMD in the radius. Altered bone geometry or other factors rather than low cortical BMD likely play a role in the increased fracture risk in TS.

Hepatic phenotypes of HNF1B gene mutations: A case of neonatal cholestasis requiring portoenterostomy and literature review

Hepatocyte nuclear factor 1-β (HNF1B) defects cause renal cysts and diabetes syndrome (RCAD), or HNF1B-maturity-onset diabetes of the young. However, the hepatic phenotype of HNF1B variants is not well studied. We present a female neonate born small for her gestational age [birth weight 2360 g; -2.02 standard deviations (SD) and birth length 45 cm; -2.40 SD at the 38^th gestational week]. She developed neonatal cholestasis due to biliary atresia and required surgical intervention (portoenterostomy) when 32-d old. Following the operation, icterus resolved, but laboratory signs of liver dysfunction persisted. She had hyperechogenic kidneys prenatally with bilateral renal cysts and pancreatic hypoplasia postnatally that led to the diagnosis of an HNF1B deletion. This represents the most severe hepatic phenotype of an HNF1B variant recognized thus far. A review of 12 published cases with hepatic phenotypes of HNF1B defects allowed us to distinguish three severity levels, ranging from neonatal cholestasis through adult-onset cholestasis to non-cholestatic liver impairment, all of these are associated with congenital renal cysts and mostly with diabetes later in life. We conclude that to detect HNF1B variants, neonates with cholestasis should be checked for the presence of renal cysts, with special focus on those who are born small for their gestational age. Additionally, patients with diabetes and renal cysts at any age who develop cholestasis and/or exocrine pancreatic insufficiency should be tested for HNF1B variants as the true etiological factor of all disease components. Further observations are needed to confirm the potential reversibility of cholestasis in infancy in HNF1B mutation/deletion carriers.

Frameshift mutations in the insulin gene leading to prolonged molecule of insulin in two families with Maturity-Onset Diabetes of the Young

Mutations in the insulin (INS) gene rarely occur in patients with Maturity-Onset Diabetes of the Young (MODY). We aimed to describe in detail two MODY families with INS mutations. The INS gene was screened by direct sequencing. The probands and their affected relatives underwent a mixed-meal test. Mutation predictions were modeled using I-TASSER and were visualized by Swiss-PdbViewer. A novel heterozygous frameshift mutation p.Gln78fs in the INS gene was found in three generations of patients with clinically distinct diabetes. The single nucleotide deletion (c.233delA) is predicted to change and prolong amino acid sequence, resulting in aberrant proinsulin without native structures of C-peptide and A-chain. In the second family, the heterozygous mutation c.188-31G>A within the terminal intron was detected. The mother and her daughter were misdiagnosed as having type 1 diabetes since the ages of 6 and 2 years, respectively. This result is in contrast to the previously described carrier of the same mutation who was diagnosed with permanent neonatal diabetes. We identified a novel coding frameshift mutation and an intronic mutation in the INS gene leading to childhood-onset diabetes. INS mutations may result in various phenotypes, suggesting that additional mechanisms may be involved in the pathogenesis and clinical manifestation of diabetes.

Muscle function in Turner syndrome: normal force but decreased power

OBJECTIVE

Although hypogonadism and SHOX gene haploinsufficiency likely cause the decreased bone mineral density and increased fracture rate associated with Turner syndrome (TS), the exact mechanism remains unclear. We tested the hypothesis that muscle dysfunction in patients with TS contributes to increased fracture risk. The secondary aim was to determine whether menarche, hormone therapy duration, positive fracture history and genotype influence muscle function parameters in patients with TS.

DESIGN

A cross-sectional study was conducted in a single university hospital referral centre between March 2012 and October 2013.

PATIENTS

Sixty patients with TS (mean age of 13·7 ± 4·5 years) were compared to the control group of 432 healthy girls.

MEASUREMENTS

A Leonardo Mechanograph(®) Ground Reaction Force Platform was used to assess muscle force (Fmax ) by the multiple one-legged hopping test and muscle power (Pmax ) by the single two-legged jump test.

RESULTS

While the Fmax was normal (mean weight-specific Z-score of 0·11 ± 0·77, P = 0·27), the Pmax was decreased in patients with TS (Z-score of -0·93 ± 1·5, P < 0·001) compared with healthy controls. The muscle function parameters were not significantly influenced by menarcheal stage, hormone therapy duration, fracture history or genotype (linear regression adjusted for age, weight and height; P > 0·05 for all).

CONCLUSION

Fmax , a principal determinant of bone strength, is normal in patients with TS. Previously described changes in bone quality and structure in TS are thus not likely related to inadequate mechanical loading but rather represent a primary bone deficit. A decreased Pmax indicates impaired muscle coordination in patients with TS.

Treated Autoimmune Thyroid Disease Is Associated with a Decreased Quality of Life among Young Persons with Type 1 Diabetes

Type 1 diabetes (T1D) in children and adolescents is relatively often accompanied by other immunopathological diseases, autoimmune thyroid disease (AITD) or celiac disease (CD). Our aim was to assess whether these conditions are associated with changes in the health-related quality of life (HRQOL) in pediatric patients with T1D. In a cross-sectional study we identified eligible 332 patients with T1D aged 8-18 years, of whom 248 (75%) together with their parents responded to the PedsQL Generic and Diabetes Modules. Compared to 143 patients without thyroid autoantibodies, 40 patients with a thyroxine-treated AITD scored lower in the overall generic HRQOL (P = 0.014), as well as in the overall diabetes-specific HRQOL (P = 0.013). After adjustment for age, gender, duration of diabetes, type of diabetes treatment, and diabetes control, this association remained statistically significant for the generic HRQOL (P = 0.023). Celiac disease was not associated with a change in the generic or diabetes-specific HRQOL (P = 0.07  and  P = 0.63, resp.). Parental scores showed no association with AITD or celiac disease, except a marginally significant decrease in the overall generic HRQOL (P = 0.039) in the T1D + AITD compared to T1D group. Our study indicates that, in pediatric patients with T1D, concomitant thyroxine-treated AITD is associated with lower quality of life.

[Liver, kidneys and diabetes: three faces of HNF1B gene deficit]

The renal cysts and diabetes syndrome (RCAD), also known as HNF1B-MODYor MODY5, is caused by the deletion or point mutation of HNF1B gene which leads to the depletion of HNF1B transcription factor. The main clinical components of RCAD include cystic kidney disease or other developmental anomalies of the kidneys and diabetes mellitus which typically manifests in the second decade of life or later. Renal disorders may lead to the development of chronic renal insufficiency already in childhood or young adulthood. The other symptoms include hepatic impairment - cholestatic jaundice in middle-aged patients, sometimes even neonatal cholestasis, atrophy of the pancreas with the impairment of exocrine pancreatic secretion and some congenital anomalies of the genital tract. As opposed to the other forms of MODY diabetes, the family history may not be positive because most of the deviations of HNF1B appear de novo. We associate RCAD in particular with adults suffering from diabetes and cystic kidney disease and/or cholestatic jaundice and children with cystic kidney disease of unclear etiology, even without the presence of diabetes. A supportive finding may be hypomagnesemia which occurs in up to 70 % of patients diagnosed with HNF1B related disease and hyperuricemia.Key words: HNF1B - MODY - RCAD - diabetes mellitus - cholestatic jaundice.

Lessons from whole-exome sequencing in MODYX families

We report the first results from whole-exome sequencing performed in families with Maturity-Onset Diabetes of the Young without a known genetic cause of diabetes (MODYX). This next generation sequencing technique pointed out that routine testing of MODY needs constant awareness and regular re-evaluation of both clinical criteria and primer sequences.

Complete androgen insensitivity syndrome: factors influencing gonadal histology including germ cell pathology

Patients with complete androgen insensitivity syndrome are at an increased risk for the development of gonadal germ cell cancer. Residual androgen receptor (AR) activity and abnormal gonadal location may influence the survival of atypical germ cells and the development of other histopathological features. To assess this, we evaluated 37 gonads from 19 patients with complete androgen insensitivity (ranging in age from 3 months to 18 years). Histological abnormalities were examined using hematoxylin and eosin-stained sections and sections stained for POU5F1 and KITLG, markers of early changes in germ cells at risk for malignant transformation. Hamartomatous nodules (HNs), Leydig cell hyperplasia (LCH), decreased germ cells, tubular atrophy and stromal fibrosis were more pronounced as age increased (P<0.001). Expected residual AR activity acted as a positive predictor only for non-malignant germ cell survival in (post)pubertal patients (P<0.05). Immunohistochemical studies indicated that delayed maturation of germ cells was present in three patients, whereas intermediate changes that occurred between delayed maturation and intratubular germ cell neoplasia, designated pre-intratubular germ cell neoplasia, were identified in four cases. Intratubular germ cell neoplasia was observed in one patient. Neither POU5F1 nor KITLG expression was dependent on expected residual AR activity. An independent effect of inguinal versus abdominal position of the gonads was difficult to assess because inguinal gonads were present primarily in the youngest individuals. In conclusion, many histological changes occur increasingly with age. Expected residual AR activity contributes to better survival of the general germ cell population in (post)pubertal age; however, it did not seem to have an important role in the survival of the germ cells at risk for malignant transformation (defined by POU5F1 positivity and KITLG overexpression) in complete androgen insensitivity. Comparison of the high percentage of patients in our study that were carrying germ cells with delayed maturation or pre-intratubular germ cell neoplasia with previously reported cumulative risk of tumor development in adult patients indicates that not all such precursor lesions in complete androgen insensitivity will progress to invasive germ cell cancer.