Skewed X-chromosome inactivation in unsolved neurodevelopmental disease cases can guide re-evaluation For X-linked genes

Despite major advances in genome technology and analysis, >50% of patients with a neurodevelopmental disorder (NDD) remain undiagnosed after extensive evaluation. A point in case is our clinically heterogeneous cohort of NDD patients that remained undiagnosed after FRAXA testing, chromosomal microarray analysis and trio exome sequencing (ES). In this study, we explored the frequency of non-random X chromosome inactivation (XCI) in the mothers of male patients and affected females, the rationale being that skewed XCI might be masking previously discarded genetic variants found on the X chromosome. A multiplex fluorescent PCR-based assay was used to analyse the pattern of XCI after digestion with HhaI methylation-sensitive restriction enzyme. In families with skewed XCI, we re-evaluated trio-based ES and identified pathogenic variants and a deletion on the X chromosome. Linkage analysis and RT-PCR were used to further study the inactive X chromosome allele, and Xdrop long-DNA technology was used to define chromosome deletion boundaries. We found skewed XCI (>90%) in 16/186 (8.6%) mothers of NDD males and in 12/90 (13.3%) NDD females, far beyond the expected rate of XCI in the normal population (3.6%, OR = 4.10; OR = 2.51). By re-analyzing ES and clinical data, we solved 7/28 cases (25%) with skewed XCI, identifying variants in KDM5C, PDZD4, PHF6, TAF1, OTUD5 and ZMYM3, and a deletion in ATRX. We conclude that XCI profiling is a simple assay that targets a subgroup of patients that can benefit from re-evaluation of X-linked variants, thus improving the diagnostic yield in NDD patients and identifying new X-linked disorders.

Mutational Spectrum and Genotype-phenotype Correlations in Neurofibromatosis Type 1 Patients from North Macedonia: Identification of Ten Novel NF1 Pathogenic Variants

Background

Neurofibromatosis type 1 (NF1) is an autosomal dominant neurocutaneous disorder, characterized by multiple café-au-lait macules, axillary and inguinal freckling, tumors of the nervous system, and iris hamartomas. More than 3,100 different pathogenic variants have been reported in the NF1 gene, including missense, nonsense, frameshift, in-frame, splicing, and large deletions.

Aims

To determine the NF1 mutational spectrum in patients with NF1 from the Republic of North Macedonia.

Study Design

A cohort study.

Methods

Molecular analyses included reverse transcription and cDNA sequencing of the NF1 gene and next-generation sequencing using the TruSight Cancer panel, along with the multiple ligation probe amplification method to detect single nucleotide variants and copy number variations. Direct DNA sequencing was also used for the family member analysis.

Results

Our 9-year study of patients suspected of having NF1 in the Republic of North Macedonia encompassed molecular characterization of 30 cases of the disease. We identified 28 unique pathogenic NF1 variants (NM_001042492.3), of which ten were novel: c.208delA; c.341_364del; c.1480_1481delTT; c.2325+1G>C; c.2495_2496dupAC; c.2533_2541del; c.4517delC; c.5844C>G; c.6971delA; c.7605_7606delGAinsAT. In addition to the variant spectrum analysis, our research revealed two positive genotype-phenotype correlations. One between the clinical manifestation of cognitive impairment and gross deletions in the NF1 gene, and the other between cognitive impairment and truncating variants located in the RAS-GAP functional domain.

Conclusion

This is the first study of NF1 patients in the Republic of North Macedonia, and it contributes ten novel variants to the global spectrum of pathogenic NF1 variants. It also corroborates the crucial importance of NF1 genetic testing for a prompt and precise diagnosis, particularly in younger patients.

Drosophila functional screening of de novo variants in autism uncovers damaging variants and facilitates discovery of rare neurodevelopmental diseases

Individuals with autism spectrum disorder (ASD) exhibit an increased burden of de novo mutations (DNMs) in a broadening range of genes. While these studies have implicated hundreds of genes in ASD pathogenesis, which DNMs cause functional consequences in vivo remains unclear. We functionally test the effects of ASD missense DNMs using Drosophila through "humanization" rescue and overexpression-based strategies. We examine 79 ASD variants in 74 genes identified in the Simons Simplex Collection and find 38% of them to cause functional alterations. Moreover, we identify GLRA2 as the cause of a spectrum of neurodevelopmental phenotypes beyond ASD in 13 previously undiagnosed subjects. Functional characterization of variants in ASD candidate genes points to conserved neurobiological mechanisms and facilitates gene discovery for rare neurodevelopmental diseases.

Missense variant contribution to USP9X-female syndrome

USP9X is an X-chromosome gene that escapes X-inactivation. Loss or compromised function of USP9X leads to neurodevelopmental disorders in males and females. While males are impacted primarily by hemizygous partial loss-of-function missense variants, in females de novo heterozygous complete loss-of-function mutations predominate, and give rise to the clinically recognisable USP9X-female syndrome. Here we provide evidence of the contribution of USP9X missense and small in-frame deletion variants in USP9X-female syndrome also. We scrutinise the pathogenicity of eleven such variants, ten of which were novel. Combined application of variant prediction algorithms, protein structure modelling, and assessment under clinically relevant guidelines universally support their pathogenicity. The core phenotype of this cohort overlapped with previous descriptions of USP9X-female syndrome, but exposed heightened variability. Aggregate phenotypic information of 35 currently known females with predicted pathogenic variation in USP9X reaffirms the clinically recognisable USP9X-female syndrome, and highlights major differences when compared to USP9X-male associated neurodevelopmental disorders.

Growing Prevalence and Incidence of Diabetes in Republic of Macedonia in the Past 5 Years Based on Data from the National System for Electronic Health Records

Introduction. Diabetes is a chronic metabolic disease characterized with a rapid progression of prevalence in last 3 decades, especially in countries with low and middle income. Next three decades this number of diabetes in the world is expected to be doubled. Early diagnosis and appropriate management of diabetes is the primary way to prevent and delay cardiovascular complications. Patients and methods. In this retrospective study, we used the data from National electronic system e-health which was performed in late 2014, wich gives us nearly precise data, and we made statistical analysis for diabetes in last 5 years (2015-2019). Results. In 2015 we have registered 103480 patients with DM, in 2016 108130 patients, in 2017 114408, in 2018 119999 and in 2019 124450 patients with DM. 95% of patients are with T2DM and 4, 1% with T1DM. According the data from State statistical office for population of Republic of Macedonia, the prevalence of T2DM for the years 2015-2019 is as follows: 5,66% in 2015, 6.13% In 2016, 6.55% I 2017, 7,06% in 2018 and 7,2% in 2019.   Conclusions. The number of registered  patients with diabetes in last 5 years has grown up for 20970 or 20%, in the last 5 years the number of patients with  type 2 diabetes has grown up for 18272 patients or 11%. The prevalence of T2DM has increased for 1.54%. Involvement of primary health care professionals has improved the early diagnosis of type 2 diabetes.

Two cases of non-syndromic congenital unilateral breast hypoplasia in one family

Micromastia or breast hypoplasia is described as underdevelopment of a woman’s mammary tissue. We present the case of a 15-year-old girl with unilateral micromastia, with familial predisposition. Ultrasound, hormonal, dysmorphic, cardiologic, genetic examinations and testing were performed. No mutation in the whole- exome sequencing was found, nor novel mutation. Some of these cases have been reported to be related to breаst cancer so further follow-up is mandatory. Therapy consists of surgical reconstruction of the affected breast. This is a rare condition and it requires a multidisciplinary approach.

Genetics in Macedonia-Following the international trends

Genetics in Macedonia—Following the international trends

Diagnostic re-evaluation of congenital hypothyroidism in Macedonia: predictors for transient or permanent hypothyroidism

BACKGROUND

Diagnostic re-evaluation is important for all patients with congenital hypothyroidism (CH) for determining the etiology and identifying transient CH cases. Our study is a first thyroxine therapy withdrawal study conducted in Macedonian CH patients for a diagnostic re-evaluation. We aimed to evaluate the etiology of CH, the prevalence of transient CH and identify predictive factors for distinguishing between permanent (PCH) and transient CH (TCH).

MATERIALS AND METHODS

Patients with CH aged >3 years underwent a trial of treatment withdrawal for 4 weeks period. Thyroid function testing (TFT), ultrasound and Technetium-99m pertechnetate thyroid scan were performed thereafter. TCH was defined when TFT remained within normal limits for at least 6-month follow-up. PCH was diagnosed when TFT was abnormal and classified according the imaging findings.

RESULTS

42 (55%) patients had PCH and 34 (45.0%) patients had TCH. Thyroid agenesia was the most prevalent form in the PCH group. Patients with TCH had lower initial thyroid-stimulating hormone (TSH) values (P < 0.0001); higher serum thyroxine levels (P = 0.0023) and lower mean doses of levothyroxine during treatment period (P < 0.0001) than patients with PCH. Initial TSH level <30.5 IU/mL and levothyroxine dose at 3 years of age <2.6 mg/kg/day were a significant predictive factors for TCH; sensitivity 92% and 100%, specificity 75.6% and 76%, respectively.

CONCLUSION

TCH presents a significant portion of patients with CH. Initial TSH value and levothyroxine dose during treatment period has a predictive role in differentiating TCH from PCH. Earlier re-evaluation, between 2 and 3 years age might be considered in some patients requiring low doses of levothyroxine.

Regional Variation in the Incidence of Congenital Hypothyroidism in Macedonia

The incidence of congenital hypothyroidism (CH) is increasing in different areas around the world. Potential causes include changes in population ethnic composition, environmental factors, changing screening program methodology and lowering of TSH cutoff levels. The incidence of CH in different regions of Macedonia has not been evaluated before. A total of 251,008 newborns from all eight regions in the country have been screened between 2002 and 2015, by measurement of the thyroid-stimulating hormone (TSH) from blood spots, sampled 48-72 h after birth, using the DELFIA assay. Overall CH incidence confirmed at birth was 1/1976. The highest CH incidence was observed in the Vardar region (1/970), while the Eastern region had the lowest incidence (1/4202; p=0.021). In the other regions, the following CH incidence was detected: Northeastern 1/1459, Pelagonia 1/1627, Polog 1/1444, Skopje 1/2430, Southwestern 1/3226, and Southeastern 1/1843. Interestingly, in the Vardar region, 4.44% of the screened newborns had a TSH concentration > 5 mIU/L, as an indicator of regional iodine deficiency, compared to the Eastern region where 1.66% of newborns had a TSH > 5 mIU/L. The higher CH incidence in some of the regions may be due to increasing exposure to environmental toxic agents and/or deficient iodine intake. Further research into the potential environmental determinants of increased CH risk is warranted.

Rare case of Killian-Pallister syndrome associated with idiopathic short stature detected with fluorescent in situ hybridization on buccal smear

Background

Killian-Pallister syndrome (KPS) is a rare form of chromosomal mosaicism and is defined by the existence of an extra chromosome 12 in some cell lines in one individual. The degree of mosaicism varies among tissues and dictates the clinical presentation of the syndrome. The clinical features of Killian-Pallister syndrome include mental retardation, typical facial dysmorphism and pigmentation defects.

Case presentation

We present a rare case of Killian-Pallister syndrome with severe form of the disease associated with isolated growth hormone deficiency and low-rate mosaicism on buccal smear. The absence of a marker chromosome 12p in lymphocyte cultures and the low degree of mosaicism lead to frequent misdiagnosis of this condition.

Conclusions

The selection of tissue sampling is crucial in establishing the diagnosis of Killian-Pallister syndrome. Fluorescent in situ hybridisation on buccal smear remains the golden standard as a screening method if a suspicion of the syndrome exists.

Optic glioma and precocious puberty in a girl with neurofibromatosis type 1 carrying an R681X mutation of NF1: case report and review of the literature

BACKGROUND

Neurofibromatosis type 1 (NF1) is a common autosomal dominant genetic disorder with an extremely variable phenotype. In childhood NF1 can be associated with optic glioma and central precocious puberty; the latter is more common when the optic chiasm is affected. The mutational spectrum of the NF1 gene is wide and complex; R681X is a rare severe mutation of the NF1 gene known to cause truncation of neurofibromin, with only ten reported cases in the literature so far.

CASE PRESENTATION

We describe a girl with NF1 associated with early central precocious puberty appearing at 2.5 years of age and optic glioma affecting the optic chiasm as seen on magnetic resonance imaging (MRI). Genetic analysis confirmed the presence of R681X. Therapy with a gonadotropin-releasing hormone agonist was instituted with good response to therapy. The lesions on MRI were stable and no significant vision impairment was present during the 6 years of follow-up.

CONCLUSION

Of the ten reported cases of NF1 due to R681X, one has presented with optic glioma and none with precocious puberty. Thus, to our knowledge, this is the first reported case of this mutation presenting with precocious puberty. We believe that this is a contribution to the few reports on the phenotype of this mutation and to the future elucidation of genotype-phenotype correlations of this disease.

Clinical practice: experience with newborn screening for congenital hypothyroidism in the Republic of Macedonia - a multiethnic country

To evaluate the thyroid screening program and to estimate the prevalence of congenital hypothyroidism (CH) among newborns in the Republic of Macedonia, we measured thyroid-stimulating hormone (TSH) levels in dried blood spot specimens using the DELFIA fluoroimmunoassay, over a period of 12 years. The TSH cutoff level was 10 mU/L blood. A total of 215,077 newborns were screened (94.76 %). Out of 254 recalled newborns (a recall rate of 0.15 %), 83 newborns with CH were detected, yielding a CH prevalence at screening of 1/2,591 (female to male ratio, 1.86:1). Of the CH cases, 47/107,754 (56.6 %) neonates were Macedonian, 29/70,330 (34.9 %) were Albanian, and 7/15,055 (8.4 %) were Roma. The thyroid gland was undetectable on ultrasound in 43 (51.8 %) newborns with CH, thyroid hypoplasia was confirmed in 8 (9.6 %), while 29 (34.9 %) had a normal thyroid gland. In three newborns (3.6 %), agenesis of one lobe was confirmed. Therapy with levothyroxin was initiated on average 11.7 days after birth.

CONCLUSION

The national thyroid newborn screening program in Macedonia has been successful and effective, providing timely diagnosis and treatment of children with congenital hypothyroidism.

Dandy-Walker malformation and Wisconsin syndrome: novel cases add further insight into the genotype-phenotype correlations of 3q23q25 deletions

Background

The Dandy-Walker malformation (DWM) is one of the commonest congenital cerebellar defects, and can be associated with multiple congenital anomalies and chromosomal syndromes. The occurrence of overlapping 3q deletions including the ZIC1 and ZIC4 genes in few patients, along with data from mouse models, have implicated both genes in the pathogenesis of DWM.

Methods and results

Using a SNP-array approach, we recently identified three novel patients carrying heterozygous 3q deletions encompassing ZIC1 and ZIC4. Magnetic resonance imaging showed that only two had a typical DWM, while the third did not present any defect of the DWM spectrum. SNP-array analysis in further eleven children diagnosed with DWM failed to identify deletions of ZIC1-ZIC4. The clinical phenotype of the three 3q deleted patients included multiple congenital anomalies and peculiar facial appearance, related to the localization and extension of each deletion. In particular, phenotypes resulted from the variable combination of three recognizable patterns: DWM (with incomplete penetrance); blepharophimosis, ptosis, and epicanthus inversus syndrome; and Wisconsin syndrome (WS), recently mapped to 3q.

Conclusions

Our data indicate that the 3q deletion is a rare defect associated with DWM, and suggest that the hemizygosity of ZIC1-ZIC4 genes is neither necessary nor sufficient per se to cause this condition. Furthermore, based on a detailed comparison of clinical features and molecular data from 3q deleted patients, we propose clinical diagnostic criteria and refine the critical region for WS.

A new case with 10q23 interstitial deletion encompassing both PTEN and BMPR1A narrows the genetic region deleted in juvenile polyposis syndrome

We report on a patient with a contiguous interstitial germline deletion of chromosome 10q23, encompassing BMPR1A and PTEN, with clinical manifestations of juvenile polyposis and minor symptoms of Cowden syndrome (CS) and Bannayan-Riley-Ruvalcaba syndrome (BRRS). The patient presented dysmorphic features as well as developmental delay at the age of 5 months. Multiple polyps along all parts of the colon were diagnosed at the age of 3 years, following an episode of a severe abdominal pain and intestinal bleeding. The high-resolution comparative genomic hybridisation revealed a 3.7-Mb deletion within the 10q23 chromosomal region: 86,329,859-90,035,024. The genotyping with four polymorphic microsatellite markers confirmed a de novo 10q deletion on the allele with a paternal origin, encompassing both PTEN and BMPR1A genes. The karyotype analysis additionally identified a balanced translocation involving chromosomes 5q and 7q, and an inversion at chromosome 2, i.e. 46,XY,t(5;7)(q13.3-q36), inv(2)(p25q34). Although many genetic defects were detected, it is most likely that the 10q23 deletion is primarily the cause for the serious phenotypic manifestations. The current clinical findings and deletion of BMPR1A indicate a diagnosis of severe juvenile polyposis, but the existing macrocephaly and PTEN deletion also point to either CS or BRRS, which cannot be ruled out at the moment because of their clinical manifestation later in life and the de novo character of the deletion. The deletion detected in our patient narrows the genetic region deleted in all reported cases with juvenile polyposis by 0.04 Mb from the telomeric side, mapping it to the region chr10:88.5-90.03Mb (GRCh37/hg19), with an overall length of 1.53 Mb.

A new case with 10q23 interstitial deletion encompassing both PTEN and BMPR1A narrows the genetic region deleted in juvenile polyposis syndrome

We report on a patient with a contiguous interstitial germline deletion of chromosome 10q23, encompassing BMPR1A and PTEN, with clinical manifestations of juvenile polyposis and minor symptoms of Cowden syndrome (CS) and Bannayan-Riley-Ruvalcaba syndrome (BRRS). The patient presented dysmorphic features as well as developmental delay at the age of 5 months. Multiple polyps along all parts of the colon were diagnosed at the age of 3 years, following an episode of a severe abdominal pain and intestinal bleeding. The high-resolution comparative genomic hybridisation revealed a 3.7-Mb deletion within the 10q23 chromosomal region: 86,329,859-90,035,024. The genotyping with four polymorphic microsatellite markers confirmed a de novo 10q deletion on the allele with a paternal origin, encompassing both PTEN and BMPR1A genes. The karyotype analysis additionally identified a balanced translocation involving chromosomes 5q and 7q, and an inversion at chromosome 2, i.e. 46,XY,t(5;7)(q13.3-q36), inv(2)(p25q34). Although many genetic defects were detected, it is most likely that the 10q23 deletion is primarily the cause for the serious phenotypic manifestations. The current clinical findings and deletion of BMPR1A indicate a diagnosis of severe juvenile polyposis, but the existing macrocephaly and PTEN deletion also point to either CS or BRRS, which cannot be ruled out at the moment because of their clinical manifestation later in life and the de novo character of the deletion. The deletion detected in our patient narrows the genetic region deleted in all reported cases with juvenile polyposis by 0.04 Mb from the telomeric side, mapping it to the region chr10:88.5-90.03Mb (GRCh37/hg19), with an overall length of 1.53 Mb.

Unique concurrent appearance of two rare conditions in a young girl: central precocious puberty due to hypothalamic hamartoma and uncommon type of diabetes

Hypothalamic hamartomas (HH) are rare congenital nonneoplastic lesions of the tuber cinereum, which usually present as precocious puberty of central origin in young girls and respond well to treatment with long acting gonadotropin releasing hormone (GnRH) analogs. No association of this condition with diabetes mellitus of any form has been reported so far. On the other hand, diabetes mellitus in children and adolescents, when it is not autoimmune type 1 diabetes, is difficult to classify. We present a girl with early onset of central precocious puberty at the age of 8 months, due to hypothalamic hamartoma. Treatment with depot of a GnRH analog for a period of 9 years and 8 months was successful, and her puberty continued 6 months after the discontinuation of triptorelin. At the age of 9 years 6 months, the girl presented with diabetes. She was negative for islet, GAD and IA2 antibodies and her insulinemia and C-peptide remained within normal limits during the 2 years of follow-up. Her metabolic control is excellent with a combination of metformin and a low-dose of mixed insulin. To our knowledge, this is the first description of the simultaneous appearance of these two endocrinological conditions.

Implementation of Fluorescent in situ hybridization (FISH) as a method for detecting microdeletion syndromes - our first experiences

Fluorescent in situ hybridisation (FISH) is a complementary cytogenetic method which has an important role in discovering unsolved cases of mental retardation and multiple anomalies. The ability of this method to detect complex and cryptic chromosomal rearrangements exceeds the resolution of the usual cytogenetic banding techniques; therefore it has a wide implementation in modern cytogenetic laboratories - in routine work, as well as for research purposes. We analysed 19 patients with microdeletion syndromes - 9 patients with Williams syndrome, 4 patients with Prader-Willi syndrome, and 6 patients with DiGeorge syndrome. On the basis of evaluation of facial dysmorphism and the presence of specific major anomalies, all the patients met the criteria for the diagnosis of the syndrome. FISH studies were performed, confirming the suspected syndrome in patients.

Premature thelarche in Macedonia: a three-year follow-up

INTRODUCTION

Premature thelarche presents as an appearance of breasts and glandular tissue in girls before the age of 8 years. It is mostly a benign and transitory variation of premature sexual development.

AIM OF THE STUDY

We evaluated a group of girls with premature thelarche for clinical and auxologic characteristics for a period of three years. We investigated the duration of the condition and eventual progression toward true idiopathic central precocious puberty.

PATIENTS, MATERIALS, METHODS

At the Department of Endocrinology and Genetics at the Pediatric Clinic in Skopje, 127 girls with premature thelarche, from all over the country, were analyzed and followed-up for a period of 3 years (2000-2003).

RESULTS AND CONCLUSIONS

Premature thelarche as a partial form of premature sexual development, in our study included 98 girls, and showed to be a benign condition, the girls are with normal height, slightly elevated weight, but with increased bone maturation and height velocity in the first year. A progression toward central precocious puberty was not registered. The duration of the condition was about two years in most of the girls, with a regression of enlarged breasts in smaller patients and with occurrence of normal puberty in older patients (Tab. 1, Fig. 3, Ref. 16). Full Text (Free, PDF) www.bmj.sk.

Pituitary pseudotumor with unusual presentation reversed shortly after the introduction of thyroxine replacement therapy

Pituitary pseudotumor (pituitary thyrotroph hyperplasia) caused by unrecognized and untreated hypothyroidism has been described as a rare condition, mostly in adults. There are only a few reports on this condition in children. Here we describe an unusual association of pituitary pseudotumor with hypothyroidism, vaginal bleeding, and growth retardation in a girl at an early stage of puberty. Hormonal testing showed low thyroxine and high TSH levels, hyperprolactinemia, low growth hormone levels and prepubertal levels of gonadotrophins. Ovarian cyst was detected by ultrasound. A large intrasellar mass expanding beyond the sella turcica was detected on MRI. Homogeneous contrast enhancement confirmed pituitary hyperplasia. Therapy with L-thyroxine resulted in rapid improvement of the clinical signs, normalization of the hormone levels, and resolution of the pituitary hyperplasia on MRI within 40 days. In children, prolonged unrecognized primary hypothyroidism might be accompanied by growth deficiency and pubertal disharmony. Pituitary hyperplasia should be sought in these cases.