Genetic diagnosis of endocrine disorders in Cyprus through the Cyprus Institute of Neurology and Genetics: an ENDO-ERN Reference Center

The report covers the current and past activities of the department Molecular Genetics-Function and Therapy (MGFT) at the Cyprus Institute of Neurology and Genetics (CING), an affiliated Reference Center for the European Reference Network on Rare Endocrine Conditions (Endo-ERN).The presented data is the outcome of > 15 years long standing collaboration between MGFT and endocrine specialists from the local government hospitals and the private sector. Up-to-date > 2000 genetic tests have been performed for the diagnosis of inherited rare endocrine disorders. The major clinical entities included Congenital Adrenal Hyperplasia (CAH) due to pathogenic variants in CYP21A2 gene and Multiple Endocrine Neoplasia (MEN) type 2 due to pathogenic variants in the RET proto-oncogene. Other rare and novel pathogenic variants in ANOS1, WDR11, FGFR1, RNF216, and CHD7 genes were also found in patients with Congenital Hypogonadotropic Hypogonadism. Interestingly, a few patients with Disorders of Sexual Differentiation (DSD) shared rare pathogenic variants in the SRD5A2, HSD17B3 and HSD3B2 while patients with Glucose and Insulin Homeostasis carried theirs in GCK and HNF1A genes. Lastly, MGFT over the last few years has established an esteemed diagnostic and research program on premature puberty with emphasis on the implication of MKRN3 gene on the onset of the disease and the identification of other prognosis biomarkers.As an Endo-ERN member MGFT department belongs to this large European network and holds the same humanistic ideals which aim toward the improvements of health care for patients with rare endocrine conditions in respect to improved and faster diagnosis.

Gonadotropin-Releasing Hormone Receptor (GnRHR) and Hypogonadotropic Hypogonadism

Human sexual and reproductive development is regulated by the hypothalamic-pituitary-gonadal (HPG) axis, which is primarily controlled by the gonadotropin-releasing hormone (GnRH) acting on its receptor (GnRHR). Dysregulation of the axis leads to conditions such as congenital hypogonadotropic hypogonadism (CHH) and delayed puberty. The pathophysiology of GnRHR makes it a potential target for treatments in several reproductive diseases and in congenital adrenal hyperplasia. GnRHR belongs to the G protein-coupled receptor family and its GnRH ligand, when bound, activates several complex and tissue-specific signaling pathways. In the pituitary gonadotrope cells, it triggers the G protein subunit dissociation and initiates a cascade of events that lead to the production and secretion of the luteinizing hormone (LH) and follicle-stimulating hormone (FSH) accompanied with the phospholipase C, inositol phosphate production, and protein kinase C activation. Pharmacologically, GnRHR can be modulated by synthetic analogues. Such analogues include the agonists, antagonists, and the pharmacoperones. The agonists stimulate the gonadotropin release and lead to receptor desensitization with prolonged use while the antagonists directly block the GnRHR and rapidly reduce the sex hormone production. Pharmacoperones include the most recent GnRHR therapeutic approaches that directly correct the misfolded GnRHRs, which are caused by genetic mutations and hold serious promise for CHH treatment. Understanding of the GnRHR's genomic and protein structure is crucial for the most appropriate assessing of the mutation impact. Such mutations in the GNRHR are linked to normosmic hypogonadotropic hypogonadism and lead to various clinical symptoms, including delayed puberty, infertility, and impaired sexual development. These mutations vary regarding their mode of inheritance and can be found in the homozygous, compound heterozygous, or in the digenic state. GnRHR expression extends beyond the pituitary gland, and is found in reproductive tissues such as ovaries, uterus, and prostate and non-reproductive tissues such as heart, muscles, liver and melanoma cells. This comprehensive review explores GnRHR's multifaceted role in human reproduction and its clinical implications for reproductive disorders.

Reduced serum concentrations of biomarkers reflecting Leydig and Sertoli cell function in male patients with congenital adrenal hyperplasia

Congenital adrenal hyperplasia (CAH) is a recessive condition that affects the adrenal glands. Despite life-long replacement therapy with glucocorticoids and mineralocorticoids, adult patients with CAH often experience impaired gonadal function. In pubertal boys and in men with CAH, circulating testosterone is produced by the adrenal glands as well as the testicular, steroidogenic cells. In this European two-center study, we evaluated the function of Leydig and Sertoli cells in 61 boys and men with CAH, primarily due to 21-hydroxylase deficiency. Despite conventional hormone replacement therapy, our results indicated a significant reduction in serum concentrations of both Leydig cell-derived hormones (i.e. insulin-like factor 3 (INSL3) and testosterone) and Sertoli cell-derived hormones (i.e. inhibin B and anti-Müllerian hormone) in adult males with CAH. Serum concentrations of INSL3 were particularly reduced in those with testicular adrenal rest tumors. To our knowledge, this is the first study to evaluate circulating INSL3 as a candidate biomarker to monitor Leydig cell function in patients with CAH.

RET Proto-Oncogene Variants in Patients with Medullary Thyroid Carcinoma from the Mediterranean Basin: A Brief Report

Multiple endocrine neoplasia type 2 (MEN2) is an autosomal dominant (AD) condition with very high penetrance and expressivity. It is characterized into three clinical entities recognized as MEN2A, MEN2B, and familial medullary thyroid carcinoma (FMTC). In both MEN2A and MEN2B, there is a manifestation of multicentric tumor formation in the major organs such as the thyroid, parathyroid, and adrenal glands where the RET proto-oncogene is expressed. The FMTC form differs from MEN2A and MEN2B, since medullary thyroid carcinoma (MTC) is the only feature observed. In this present brief report, we demonstrate a collection of RET proto-oncogene genotype data from countries around the Mediterranean Basin with variable characteristics. As expected, a great extent of the Mediterranean RET proto-oncogene genotype data resemble the data reported globally. Most interestingly, higher frequencies are observed in the Mediterranean region for specific pathogenic RET variants as a result of local prevalence. The latter can be explained by founder effect phenomena. The Mediterranean epidemiological data that are presented herein are very important for domestic patients, their family members' evaluation, and ultimately their treatment.

The pathogenic p.Gln319Ter variant is not causing congenital adrenal hyperplasia when inherited in one of the duplicated CYP21A2 genes

Objective

The study aimed to identify the pathogenic status of p.Gln319Ter (NM_000500.7: c.955C>T) variant when inherited in a single CYP21A2 gene (bimodular RCCX haplotype) and to discriminate between a non-causing congenital adrenal hyperplasia (CAH) allele when inherited in a duplicated and functional CYP21A2 gene context (trimodular RCCX haplotype).

Methods

38 females and 8 males with hyperandrogenemia, previously screened by sequencing and identified as carriers for the pathogenic p.Gln319Ter, were herein tested by multiplex ligation-dependent probe amplification (MLPA) and a real-time PCR Copy number Variation (CNV) assay.

Results

Both MLPA and real-time PCR CNV analyses confirmed a bimodular and pathogenic RCCX haplotype with a single CYP21A2 in 19/46 (41.30%) p.Gln319Ter carriers and who in parallel all shared elevated 17-OHP levels. The remaining 27 individuals that also carried the p.Gln319Ter exhibited low 17-OHP levels as a result of their carriership of a duplicated CYP21A2 with a trimodular RCCX haplotype. Interestingly, all of these individuals also carried in linkage disequilibrium with p.Gln319Ter two single nucleotide polymorphisms, the c.293-79G>A (rs114414746) in intron 2 and the c.*12C>T (rs150697472) in the 3'-UTR. Therefore, these variants can be used to distinguish between pathogenic and non-pathogenic genomic contexts of the c.955T (p.Gln319) in the genetic diagnosis of congenital adrenal hyperplasia (CAH).

Conclusion

The employed methodologies identified a considerable number of individuals with non-pathogenic p.Gln319Ter from the individuals that typically carry the pathogenic p.Gln319Ter in a single CYP21A2. Therefore, it is extremely important the detection of such haplotypes for the prenatal diagnosis, treatment and genetic counseling in patients with CAH.

Salt-wasting congenital adrenal hyperplasia phenotype as a result of the TNXA/TNXB chimera 1 (CAH-X CH-1) and the pathogenic IVS2-13A/C > G in CYP21A2 gene

BACKGROUND

Genetic diversity of mutations in the CYP21A2 gene is the main cause of the monogenic congenital adrenal hyperplasia (CAH) disorder. On chromosome 6p21.3, the CYP21A2 gene is partially overlapped by the TNXB gene, the two residing in tandem with their highly homologous corresponding pseudogenes (CYP21A1P and TNXA), which leads to recurrent homologous recombination.

METHODS AND RESULTS

In the present study, the genetic status of an ethnic Greek-Cypriot family, with a female neonate that was originally classified as male and manifested the salt-wasting (SW) form, is presented. Genetic defects in the CYP21A2 and TNXB genes were investigated by Sanger sequencing multiplex ligation-dependent probe amplification (MLPA) and a real-time PCR assay. The neonate carried in compound heterozygosity the TNXA/TNXB chimeric gene complex (termed CAH-X CH-1) that results in a contiguous CYP21A2 and TNXB deletion and in her second allele the pathogenic IVS2-13A/C > G (c.655A/C > G) in CYP21A2.

CONCLUSIONS

The classic SW-CAH due to 21-hydroxylase (21-OH) deficiency may result from various complex etiological mechanisms and, as such, can involve the formation of monoallelic TNXA/TNXB chimeras found in trans with other CYP21A2 pathogenic variants. This is a rare case of CAH due to 21-hydroxylase deficiency, which elucidates the role of the complex RCCX CNV structure in the development of the disease. Identification of the correct CAH genotypes for a given phenotype is of considerable value in assisting clinicians in prenatal diagnosis, appropriate treatment, and genetic counseling.

AB1508 A NOVEL PATHOGENIC VARIANT IN ZNF462 GENE ASSOCIATED WITH WEISS-KRUSZKA SYNDROME AND SLE

Background

Weiss-Kruszka syndrome (WSKA) is an autosomal dominant congenital anomaly syndrome due to mutations in the ZNF462 gene and manifests with developmental delay and multiple craniofacial abnormalities with variable expressivity1. It is also characterized by cognitive impairment, whilst about a third of the affected individuals belong to the autism spectrum. Although the disease is inherited with the autosomal dominant manner, most of the described subjects (95%) had de novo variants with no affected family members1. WSKA has been recently described and only 26 (including our patient) affected individuals have been classified to date2. Systemic lupus erythematosus (SLE) is a systemic autoimmune disease characterized by the presence of autoantibodies and multi-organ inflammation. Genetic factors might play an important role in disease pathogenesis in patients with childhood-onset SLE.

Objectives

To describe the case of a SLE patient who was found to have WSKA related to a novel pathogenic autosomal dominant (AD) variant in the ZNF462 gene, and inform clinicians of a possible association between the 2 conditions.

Methods

A 25-year-old Caucasian female with a history of SLE, diagnosed at the age of 14, manifested with malar rash, Raynaud’s phenomenon, arthritis, thrombocytopenia, positive ANA, ds-DNA antibody and hypocomplementemia. At the age of 17, she developed renal dysfunction due to lupus nephritis class IV, and she was treated with glucocorticoids (GCs), cyclophosphamide and hydroxychloroquine. In Oct 2020, she was admitted to the hospital for thrombotic thrombocytopenic purpura due to lupus exacerbation. She was successfully treated with GCs, plasma exchange and rituximab. During her hospitalization, the presence of various clinical features raised the suspicion of a genetic syndrome. First, the patient exhibited dysmorphic features such as hypertelorism, prognathism, arched eyebrows, flattened nasal bridge, small upper lip, mild intellectual disability, and a history of childhood-onset SLE. Whole exome sequencing (WES) by NGS was used for the genetic investigation of the patient.

Figure 1.

Results

The patient underwent genetic evaluation with WES and the novel heterozygous AD pathogenic variant c.4142delT (p.lle1381ThrfsTer16) in ZNF462 gene was identified. Confirmation of the identified variant was also verified by sanger sequencing. Pathogenic variants in the ZNF462 gene were previously described in patients with the recently reported WSKA of which several characteristics are compatible with our patient’s features. The ZFN462 encodes a zinc-finger transcription factor that plays a role in embryonic development, transcriptional regulation, and chromatin remodelling. Given that chromatin remodelling has been implicated in the pathogenesis of SLE, the association of this novel ZNF462 variant in the development of SLE, needs to be determined3.

Conclusion

This is the first report of a patient with coexisting SLE and WSKA due to a novel variant. It illustrates the need for further research in order to elucidate any possible pathophysiologic link among the 2 conditions.

References

[1]Weiss K, Wigby K, Fannemel M, Henderson LB, Beck N, Ghali N, Study DDD, Anderlid BM, Lundin J, Hamosh A, Jones MC, Ghedia S, Muenke M, Kruszka P. Haploinsufficiency of ZNF462 is associated with craniofacial anomalies, corpus callosum dysgenesis, ptosis, and developmental delay. Eur J Hum Genet. 2017 Aug;25(8):946-951. doi: 10.1038/ejhg.2017.86. Epub 2017 May 17. PMID: 28513610; PMCID: PMC5567153.

[2]Park J, Ha DJ, Seo GH, Maeng S, Kang SM, Kim S, Lee JE. Empty Sella Syndrome Associated with Growth Hormone Deficiency: the First Case Report of Weiss-Kruszka Syndrome. J Korean Med Sci. 2021 May 10;36(18):e133. doi: 10.3346/jkms.2021.36.e133. PMID: 33975400; PMCID: PMC8111047.

[3]Surace AEA, Hedrich CM. The Role of Epigenetics in Autoimmune/Inflammatory Disease. Front Immunol. 2019 Jul 4;10:1525. doi: 10.3389/fimmu.2019.01525. PMID: 31333659; PMCID: PMC6620790.

Disclosure of Interests

None declared

Prenatal dexamethasone treatment for classic 21-hydroxylase deficiency in Europe

OBJECTIVE

To assess the current medical practice in Europe regarding prenatal dexamethasone (Pdex) treatment of congenital adrenal hyperplasia (CAH) due to 21-hydroxylase deficiency.

DESIGN AND METHODS

A questionnaire was designed and distributed, including 17 questions collecting quantitative and qualitative data. Thirty-six medical centres from 14 European countries responded and 30 out of 36 centres were reference centres of the European Reference Network on Rare Endocrine Conditions, EndoERN.

RESULTS

Pdex treatment is currently provided by 36% of the surveyed centres. The treatment is initiated by different specialties, that is paediatricians, endocrinologists, gynaecologists or geneticists. Regarding the starting point of Pdex, 23% stated to initiate therapy at 4-5 weeks postconception (wpc), 31% at 6 wpc and 46 % as early as pregnancy is confirmed and before 7 wpc at the latest. A dose of 20 µg/kg/day is used. Dose distribution among the centres varies from once to thrice daily. Prenatal diagnostics for treated cases are conducted in 72% of the responding centres. Cases treated per country and year vary between 0.5 and 8.25. Registries for long-term follow-up are only available at 46% of the centres that are using Pdex treatment. National registries are only available in Sweden and France.

CONCLUSIONS

This study reveals a high international variability and discrepancy in the use of Pdex treatment across Europe. It highlights the importance of a European cooperation initiative for a joint international prospective trial to establish evidence-based guidelines on prenatal diagnostics, treatment and follow-up of pregnancies at risk for CAH.

Methylation status of hypothalamic Mkrn3 promoter across puberty

Makorin RING finger protein 3 (MKRN3) is an important factor located on chromosome 15 in the imprinting region associated with Prader-Willi syndrome. Imprinted MKRN3 is expressed in hypothalamic regions essential for the onset of puberty and mutations in the gene have been found in patients with central precocious puberty. The pubertal process is largely controlled by epigenetic mechanisms that include, among other things, DNA methylation at CpG dinucleotides of puberty-related genes. In the present study, we investigated the methylation status of the Mkrn3 promoter in the hypothalamus of the female mouse before, during and after puberty. Initially, we mapped the 32 CpG dinucleotides in the promoter, the 5'UTR and the first 50 nucleotides of the coding region of the Mkrn3 gene. Moreover, we identified a short CpG island region (CpG islet) located within the promoter. Methylation analysis using bisulfite sequencing revealed that CpG dinucleotides were methylated regardless of developmental stage, with the lowest levels of methylation being found within the CpG islet region. In addition, the CpG islet region showed significantly lower methylation levels at the pre-pubertal stage when compared with the pubertal or post-pubertal stage. Finally, in silico analysis of transcription factor binding sites on the Mkrn3 CpG islet identified the recruitment of 29 transcriptional regulators of which 14 were transcriptional repressors. Our findings demonstrate the characterization and differential methylation of the CpG dinucleotides located in the Mkrn3 promoter that could influence the transcriptional activity in pre-pubertal compared to pubertal or post-pubertal period. Further studies are needed to clarify the possible mechanisms and effects of differential methylation of the Mkrn3 promoter.

Molecular modelling of novel ADCY3 variant predicts a molecular target for tackling obesity

Severe early-onset obesity is mainly attributed to single gene variations of the hypothalamic leptin-melanocortin system, which is critical for controlling the balance between appetite and energy expenditure. Adenylate cyclase 3 (ADCY3), a transmembrane enzyme localized in primary neuronal cilia, is a key genetic candidate, which appears to have an essential role in regulating body weight. The present study aimed to identify ADCY3 genetic variants in severely obese young patients of Greek-Cypriot origin by genomic sequencing. Apart from previously reported variants, the novel and probably pathogenic variant c.349T>A, causing a p.Leu117Met substitution within one of the two pseudo-symmetric halves of the transmembrane part of the protein, was reported. Molecular modelling analysis used to delineate bonding interactions within the mutated protein structure strongly suggested a change in interactive forces and energy levels affecting the pseudo-twofold symmetry of the transmembrane domain of the protein and probably its catalytic function. These results support the involvement of ADCY3 in the pathology of the disease and point towards the requirement of defining protein function and evaluating the clinical significance of the detected variants.

Demographic characteristics, clinical and laboratory features, and the distribution of pathogenic variants in the CFTR gene in the Cypriot cystic fibrosis (CF) population demonstrate the utility of a national CF patient registry

BACKGROUND

Specialized clinical care for cystic fibrosis (CF) in Cyprus, a small island country, has been implemented since the 1990s. However, only recently, a national CF patient registry has been established for the systematic recording of patients' data. In this study, we aim to present data on the epidemiological, genotypic and phenotypic features of CF patients in the country from the most recent data collection in 2019, with particular emphasis on notable rare or unique cases.

RESULTS

Overall, data from 52 patients are presented, 5 of whom have deceased and 13 have been lost to follow-up in previous years. The mean age at diagnosis was 7.2 ± 12.3 years, and the mean age of 34 alive patients by the end of 2019 was 22.6 ± 13.2 years. Patients most commonly presented at diagnosis with acute or persistent respiratory symptoms (46.2%), failure to thrive or malnutrition (40.4%), and dehydration or electrolyte imbalance (32.7%). Sweat chloride levels were diagnostic (above 60 mmol/L) in 81.8% of examined patients. The most common identified mutation was p.Phe508del (F508del) (45.2%), followed by p.Leu346Pro (L346P) (6.7%), a mutation detected solely in individuals of Cypriot descent. The mean BMI and FEV1 z-scores were 0.2 ± 1.3 and - 2.1 ± 1.7 across all age groups, respectively, whereas chronic Pseudomonas aeruginosa colonization was noted in 26.9% of patients. The majority of patients (74.5%) were eligible to receive at least one of the available CFTR modulator therapies. In 25% of patients we recovered rare or unique genotypic profiles, including the endemic p.Leu346Pro (L346P), the rare CFTR-dup2, the co-segregated c.4200_4201delTG/c.489 + 3A > G, and the polymorphism p.Ser877Ala.

CONCLUSIONS

CF patient registries are particularly important in small or isolated populations, such as in Cyprus, with rare or unique disease cases. Their operation is necessary for the optimization of clinical care provided to CF patients, enabling their majority to benefit from evolving advances in precision medicine.

Pathogenic and Low-Frequency Variants in Children With Central Precocious Puberty

Background

Central precocious puberty (CPP) due to premature activation of GnRH secretion results in early epiphyseal fusion and to a significant compromise in the achieved final adult height. Currently, few genetic determinants of children with CPP have been described. In this translational study, rare sequence variants in MKRN3, DLK1, KISS1, and KISS1R genes were investigated in patients with CPP.

Methods

Fifty-four index girls and two index boys with CPP were first tested by Sanger sequencing for the MKRN3 gene. All children found negative (n = 44) for the MKRN3 gene were further investigated by whole exome sequencing (WES). In the latter analysis, the status of variants in genes known to be related with pubertal timing was compared with an in-house Cypriot control cohort (n = 43). The identified rare variants were initially examined by in silico computational algorithms and confirmed by Sanger sequencing. Additionally, a genetic network for the MKRN3 gene, mimicking a holistic regulatory depiction of the crosstalk between MKRN3 and other genes was designed.

Results

Three previously described pathogenic MKRN3 variants located in the coding region of the gene were identified in 12 index girls with CPP. The most prevalent pathogenic MKRN3 variant p.Gly312Asp was exclusively found among the Cypriot CPP cohort, indicating a founder effect phenomenon. Seven other CPP girls harbored rare likely pathogenic upstream variants in the MKRN3. Among the 44 CPP patients submitted to WES, nine rare DLK1 variants were identified in 11 girls, two rare KISS1 variants in six girls, and two rare MAGEL2 variants in five girls. Interestingly, the frequent variant rs10407968 (p.Gly8Ter) of the KISS1R gene appeared to be less frequent in the cohort of patients with CPP.

Conclusion

The results of the present study confirm the importance of the MKRN3-imprinted gene in genetics of CPP and its key role in pubertal timing. Overall, the results of the present study have emphasized the importance of an approach that aligns genetics and clinical aspects, which is necessary for the management and treatment of CPP.

Late diagnosis of 3β-Hydroxysteroid dehydrogenase deficiency: the pivotal role of gas chromatography-mass spectrometry urinary steroid metabolome analysis and a novel homozygous nonsense mutation in the HSD3B2 gene

OBJECTIVES

3β-Hydroxysteroid dehydrogenase (3β-HSD) deficiency is a rare type of congenital adrenal hyperplasia caused by recessive loss-of-function mutations in HSD3B2 gene.

CASE PRESENTATION

We report an 8.5-year-old, 46XY, Roma boy with advanced adrenarche signs born to consanguineous parents. He was born at term with ambiguous genitalia. At 15 days of age, he underwent replacement therapy with hydrocortisone and fludrocortisone due to a salt wasting (SW) crisis and adrenal insufficiency. At 3.5 years, he was admitted again with SW crisis attributed to the low - unadjusted to body surface area - hydrocortisone dose and presented with bilateral gynecomastia and adrenarche. At 8.5 years, his bone age was four years more advanced than his chronological age and he was prepubertal, with very high testosterone levels. Gas chromatography-mass spectrometry (GC-MS) urinary steroid metabolome analysis revealed the typical steroid metabolic fingerprint of 3β-HSD deficiency. Sequencing of the HSD3B2 gene identified in homozygosity the novel p.Lys36Ter nonsense mutation. Furthermore, this patient was found to be heterozygous for p.Val281Leu in the CYP21A2 gene. Both parents were identified as carriers of the p.Lys36Ter in HSD3B2.

CONCLUSIONS

A novel nonsense p.Lys36Ter mutation in HSD3B2 was identified in a male patient with hypospadias. 3β-HSD deficiency due to mutations in the HSD3B2 gene is extremely rare and the finding of a patient with this rare type of disorders of sex development (DSD) is one of the very few reported to date. The complexity of such diseases requires a multidisciplinary team approach regarding the diagnosis and follow-up.

Polycystic ovarian syndrome in adolescents: From diagnostic criteria to therapeutic management

Polycystic ovarian syndrome is a common endocrinologic condition diagnosed in women of childbearing age. It is primarily associated with androgen excess and ovarian dysfunction, which contribute to menstrual irregularity, oligo-anovulation, infertility, hirsutism and acne. It is associated with several systemic conditions, including type 2 diabetes mellitus, cardiovascular disease, obesity and neuropsychological disorders. The exact pathophysiology and clinical features are highly variable and, thus, there is still controversy in defining the diagnostic criteria. In this review, we outline the main diagnostic criteria, discuss the mechanisms involved in the complex pathogenesis, and present the associated clinical manifestations and therapeutic management of the syndrome in adolescents.

Neurophysiological and Genetic Findings in Patients With Juvenile Myoclonic Epilepsy

Objective

Transcranial magnetic stimulation (TMS), a non-invasive procedure, stimulates the cortex evaluating the central motor pathways. The response is called motor evoked potential (MEP). Polyphasia results when the response crosses the baseline more than twice (zero crossing). Recent research shows MEP polyphasia in patients with generalized genetic epilepsy (GGE) and their first-degree relatives compared with controls. Juvenile Myoclonic Epilepsy (JME), a GGE type, is not well studied regarding polyphasia. In our study, we assessed polyphasia appearance probability with TMS in JME patients, their healthy first-degree relatives and controls. Two genetic approaches were applied to uncover genetic association with polyphasia.

Methods

20 JME patients, 23 first-degree relatives and 30 controls underwent TMS, obtaining 10–15 MEPs per participant. We evaluated MEP mean number of phases, proportion of MEP trials displaying polyphasia for each subject and variability between groups. Participants underwent whole exome sequencing (WES) via trio-based analysis and two-case scenario. Extensive bioinformatics analysis was applied.

Results

We identified increased polyphasia in patients (85%) and relatives (70%) compared to controls (47%) and significantly higher mean number of zero crossings (i.e., occurrence of phases) (patients 1.49, relatives 1.46, controls 1.22; p < 0.05). Trio-based analysis revealed a candidate polymorphism, p.Glu270del,in SYT14 (Synaptotagmin 14), in JME patients and their relatives presenting polyphasia. Sanger sequencing analysis in remaining participants showed no significant association. In two-case scenario, a machine learning approach was applied in variants identified from odds ratio analysis and risk prediction scores were obtained for polyphasia. The results revealed 61 variants of which none was associated with polyphasia. Risk prediction scores indeed showed lower probability for non-polyphasic subjects on having polyphasia and higher probability for polyphasic subjects on having polyphasia.

Conclusion

Polyphasia was present in JME patients and relatives in contrast to controls. Although no known clinical symptoms are linked to polyphasia this neurophysiological phenomenon is likely due to common cerebral electrophysiological abnormality. We did not discover direct association between genetic variants obtained and polyphasia. It is likely these genetic traits alone cannot provoke polyphasia, however, this predisposition combined with disturbed brain-electrical activity and tendency to generate seizures may increase the risk of developing polyphasia, mainly in patients and relatives.

GnRH Deficient Patients With Congenital Hypogonadotropic Hypogonadism: Novel Genetic Findings in ANOS1, RNF216, WDR11, FGFR1, CHD7, and POLR3A Genes in a Case Series and Review of the Literature

Background: Congenital hypogonadotropic hypogonadism (CHH) is a rare genetic disease caused by Gonadotropin-Releasing Hormone (GnRH) deficiency. So far a limited number of variants in several genes have been associated with the pathogenesis of the disease. In this original research and review manuscript the retrospective analysis of known variants in ANOS1 (KAL1), RNF216, WDR11, FGFR1, CHD7, and POLR3A genes is described, along with novel variants identified in patients with CHH by the present study. Methods: Seven GnRH deficient unrelated Cypriot patients underwent whole exome sequencing (WES) by Next Generation Sequencing (NGS). The identified novel variants were initially examined by in silico computational algorithms and structural analysis of their predicted pathogenicity at the protein level was confirmed. Results: In four non-related GnRH males, a novel X-linked pathogenic variant in ANOS1 gene, two novel autosomal dominant (AD) probably pathogenic variants in WDR11 and FGFR1 genes and one rare AD probably pathogenic variant in CHD7 gene were identified. A rare autosomal recessive (AR) variant in the SRA1 gene was identified in homozygosity in a female patient, whilst two other male patients were also, respectively, found to carry novel or previously reported rare pathogenic variants in more than one genes; FGFR1/POLR3A and SRA1/RNF216. Conclusion: This report embraces the description of novel and previously reported rare pathogenic variants in a series of genes known to be implicated in the biological development of CHH. Notably, patients with CHH can harbor pathogenic rare variants in more than one gene which raises the hypothesis of locus-locus interactions providing evidence for digenic inheritance. The identification of such aberrations by NGS can be very informative for the management and future planning of these patients.

46,XY complete gonadal dysgenesis in a familial case with a rare mutation in the desert hedgehog (DHH) gene

PURPOSE

Disorders of sex development (DSD) have been linked to gene defects that lead to gonadal dysgenesis. Herein, we aimed to identify the genetic cause of gonadal dysgenesis in a patient with primary amenorrhoea tracing it to a phenotypic female carrying a 46,XY karyotype of a consanguineous family.

METHODS AND RESULTS

Whole exome sequencing (WES) was performed and revealed in homozygosity the rare and only once reported p.Arg164Pro missense mutation in exon 2 of the desert hedgehog (DHH) gene. Sanger sequencing was used to validate this candidate variant both in the patient, the parents, and two siblings. Both brother and sister of the index patient were found negative for the p.Arg164Pro mutation, while the consanguineous parents were found to carry the mutation in the heterozygous state. Neither the parents nor the unaffected siblings showed any reproductive malformations.

CONCLUSIONS

Defects in the DHH gene have been reported as a very rare cause of DSD, and this report increases the number of 46,XY gonadal dysgenesis cases. Additionally, the present study highlights the importance of genetic validation of patients with DSD, since this is likely to alleviate the considerable psychological distress experienced by both the patient and the parents.

The Spectrum of Genetic Defects in Congenital Adrenal Hyperplasia in the Population of Cyprus: A Retrospective Analysis

Congenital adrenal hyperplasia (CAH) due to 21-hydroxylase deficiency (21-OHD) is caused by mutations in the CYP21A2 gene. The study refers to CAH patients of Greek-Cypriot ancestry between years 2007 and 2018. One hundred and twenty patients with various degrees of CAH were categorized and genotyped. The patients were categorized in 4 mutation groups based on their clinical and biochemical findings. The majority of patients (85.0%) belonged to the non-classic (NC)-CAH form and the disorder was more often diagnosed in females (71.7%). The most severe classic salt-wasting (SW) form was identified in 11 neonates (9.2%). Seven (5.8%) children were also identified with the simple virilizing (SV) form and a median presentation age of 5 years [interquartile range (IQR) 3.2-6.5]. In the 240 nonrelated alleles, the most frequent mutation was p.Val281Leu (60.0%) followed by c.655 A/C>G (IVS2-13A/C>G) (8.8%), p.Pro453Ser (5.8%), DelEx1-3 (4.6%), p.Val304Met (4.6%), and p.Gln318stop (4.2%). Other less frequent mutations including rare deletions were also identified. Following our recent report that the true carrier frequency of CYP21A2 in Greek-Cypriots is 1:10, this study reports that the CAH prevalence is predicted around 1.7 cases per 10 000 people. Therefore, the up-to-date 120 CAH patients identified by our group make only the 6.9% of the ones estimated (approximately 1750) to exist in the Greek Cypriot population. The compiled data from a coherent population such as the Greek-Cypriot could be valuable for the antenatal diagnosis, management and genetic counselling of the existing and prospect families with CAH.

Phenotype variability and different genotype of four patients with thyroid hormone resistance syndrome due to variants in the THRB gene

BACKGROUND

  Resistance to thyroid hormone (RTH) is a rare dominantly inherited disorder mainly due to variants in the THRB gene leading to decreased end-organ responsiveness to thyroid hormones.

CASE REPORT

Clinical and molecular characteristics of four patients with RTH are described. Four patients with various phenotypes were studied; two prepubertal boys and two adults (one male and one female). Sequencing analysis of the THRB was performed. All individuals had persistently elevated free thyroxine and/or free triiodothyronine associated with non-suppressed thyroid-stimulating hormone (TSH), and all had non-autoimmune goiters of various sizes. In both adults, antithyroid drugs were previously administered without successful suppression of the thyroid hormones. The 27-year-old female had resting tachycardia as the only symptom. The 35-year-old male had a degree of cognitive impairment and was initially diagnosed with atrial fibrillation. The eight-year-old boy was diagnosed with attention deficit disorder and had resting tachycardia. The oldest boy (age nine years) underwent thyroid function tests as a part of the investigation for obesity and learning difficulties. Direct sequencing analysis of the THRB gene showed three previously reported variants: p.His435Leu (c.1304A>T) in the 35-year-old male, p.Pro453Thr (c.1357C>A) in the oldest boy, and p.Arg438Cys (c.1312C>T) variant in the other two patients.

CONCLUSIONS

Various phenotypes characterize common variants in the THRB gene, asymptomatic, thyroid hormone deprivation symptoms, or thyroid hormone excess symptoms. RTH should be suspected in both adults and children with elevated thyroid hormones and not suppressed TSH. A prompt molecular diagnosis and genetic counseling could prevent unnecessary tests and inappropriate treatments. HIPPOKRATIA 2019, 23(3): 135-139.

A novel heterozygous duplication of the SLC12A3 gene in two Gitelman syndrome pedigrees: indicating a founder effect

Gitelman syndrome is an autosomal recessive salt-wasting tubulopathy caused by mutations in the SLC12A3 gene. A female and a male sibling from two unrelated Greek-Cypriot families presenting with a severe salt-wasting tubulopathy due to compound heterozygous mutations of a novel duplication and a previously reported missense mutation in the SLC12A gene are described. Sanger sequencing was used to identify possible mutations in the SLC12A3 gene. For the detection of duplications/conversions and deletions in the same gene, Multiplex ligation probe amplification (MLPA) analysis was performed. Direct sequencing and MLPA analysis of the SLC12A3 gene identified two compound heterozygous mutations in both unrelated probands. Both probands were identified to carry in compound heterozygosity the known p.Met581Lys and a novelheterozygous duplication of exons 9-14 (E9_E14dup). The diagnosis of Gitelman syndrome was made through clinical assessment, biochemical screening and genetic analysis. The identification of the novel SLC12A3 duplication seems to be characteristic of Greek-Cypriot patients and suggests a possible ancestral mutational event that has spread in Cyprus due to a possible founder effect. Testing for Gitelman syndrome probable variants can be performed before proceeding to a full gene sequencing dropping the diagnostic cost. In addition, this report adds to the mutational spectrum observed.

Central Precocious Puberty Caused by Novel Mutations in the Promoter and 5'-UTR Region of the Imprinted MKRN3 Gene

Background: Central Precocious Puberty (CPP) is clinically defined by the development of secondary sexual characteristics before the age of 8 years in girls and 9 years in boys. To date, mutations in the coding region of KISS1, KISS1R, PROKR2, DLK1, and MKRN3 genes have been reported as causative for CPP. This study investigated the presence of causative mutations in both the promoter and the 5'-UTR regions of the MKRN3 gene. Methods: Sanger DNA sequencing was used for screening the proximal promoter and 5'-UTR region of the MKRN3 gene in a group of 73 index girls with CPP. Mutations identified were cloned in luciferase reporter gene vectors and transiently transfected in GN11 cells in order to check for changes in the activity of the MKRN3 promoter. GN11 cells were previously checked for Mkrn3 expression using lentivirus mediated knock-down. In silico analysis was implemented for the detection of changes in the mRNA secondary structure of the mutated MKRN3 5'-UTR. Results: Three novel heterozygous mutations (-166, -865, -886 nt upstream to the transcription start site) located in the proximal promoter region of the MKRN3 gene were identified in six non-related girls with CPP. Four of these girls shared the -865 mutation, one the -166, and another one the -886. A 5'-UTR (+13 nt downstream to the transcription start site) novel mutation was also identified in a girl with similar clinical phenotype. Gene reporter assay evaluated the identified promoter mutations and demonstrated a significant reduction of MKRN3 promoter activity in transfected GN11 cells. In silico analysis for the mutated 5'-UTR predicted a significant change of the mRNA secondary structure. The minimum free energy (MFE) of the mutated 5'-UTR was higher when compared to the corresponding wild-type indicating less stable RNA secondary structure. Conclusion: Our findings demonstrated novel genetic alterations in the promoter and 5'-UTR regulatory regions of the MKRN3 gene. These changes add to another region to check for the etiology of CPP.

Multiple endocrine neoplasia 2 in Cyprus: evidence for a founder effect

PURPOSE

Multiple endocrine neoplasia type 2 (MEN2) affects patients with RET proto-oncogene mutations. This cohort study refers to patients who were diagnosed with familial medullary thyroid carcinoma (MTC) and underwent RET genetic testing in Cyprus between years 2002 and 2017.

METHODS AND PATIENTS

Forty patients underwent RET testing by Sanger sequencing of exons 10-11 and 13-16. Genotyping with STR genetic markers flanking the RET gene along with Y-chromosome genotyping and haplogroup assignment was also performed.

RESULTS

RET mutations were identified in 40 patients from 11 apparently unrelated Cypriot families and two non-familial sporadic cases. Nine probands (69.2%) were heterozygous for p.Cys618Arg, one (7.7%) for p.Cys634Phe, one (7.7%) for the somatic delE632-L633 and two (15.4%) for p.Met918Thr mutations. The mean age at MTC diagnosis of patients carrying p.Cys618Arg was 36.8 ± 14.2 years. The age of pheo diagnosis ranged from 26 to 43 years and appeared simultaneously with MTC in 5/36 (13.9%) cases. The high frequency of the p.Cys618Arg mutation suggested a possible ancestral mutational event. Haplotype analysis was performed in families with and without p.Cys618Arg. Six microsatellite markers covering the RET gene and neighboring regions identified one core haplotype associated with all patients carrying p.Cys618Arg mutation.

CONCLUSIONS

The mutation p.Cys618Arg is by far the most prevalent mutation in Cyprus followed by other reported mutations of variable clinical significance. The provided molecular evidence speculates p.Cys618Arg mutation as an ancestral mutation that has spread in Cyprus due to a possible founder effect.

46,XY Disorder of Sex Development due to 17-Beta Hydroxysteroid Dehydrogenase Type 3 Deficiency in an Infant of Greek Origin

17-beta hydroxysteroid dehydrogenase type 3 (17βHSD-3) enzyme catalyzes the conversion of androstenedione (Δ4) to testosterone (T) in the testes of the developing fetus, thus playing a crucial role in the differentiation of the gonads and in establishing the male sex phenotype. Any mutation in the encoding gene (HSD17B3) can lead to varying degrees of undervirilization of the affected male, ranging from completely undervirilized external female genitalia to predominantly male with micropenis and hypospadias. We present here an infant who was referred to our clinic because of ambiguous genitalia at birth. Gonads were palpable in the inguinal canal bilaterally and no Müllerian structures were identified on pelvic ultrasound. Because of a low T/Δ4 ratio after a human chorionic gonadotropin stimulation test, a tentative diagnosis of 17βHSD-3 deficiency was made which was confirmed after genetic analysis of the HSD17B3 gene of the patient. The molecular analysis identified compound heterozygosity of two previously described mutations and could offer some further validation for the idea of a founder effect for 655-1;G→A mutation in the Greek population.

Genotype Is Associated to the Degree of Virilization in Patients With Classic Congenital Adrenal Hyperplasia

Background: Molecular defects of CYP21A2 consistently decrease 21-hydroxylase activity and result in a variable expression of disease severity in patients with congenital adrenal hyperplasia (CAH). Aim: The genotype and biochemical findings were examined in an attempt to reveal any association to the degree of virilization in classic CAH patients. Methods: The study included 18 CAH patients with complete characterization of CYP21A2 mutations and were sorted based on the severity of the inherited mutations and the expected percentage of 21-hydroxylase enzyme activity. Results: Eleven out of the 18 patients manifested the SW form with the remaining seven exhibiting the SV form. The most frequent genetic defect in the classic salt-wasting (SW) and simple virilising (SV) forms was the IVS2-13A/C>G (36.1%) mutation, followed by delEX1-3 (19.4%) and p.Ile172Asn (19.4%). Four patients, who shared a combination of two mutations belonging to the most severe type, manifested only the SW form. Four out of five patients who shared homozygosity in the IVS2-13A/C>G mutation, demonstrated the SW form and only one demonstrated the SV form. All four patients who shared the p.Ile172Asn mutation, either in the homozygous or compound heterozygous state, manifested the SV form. Interestingly, a female neonate with SW, bearing the IVS2-13A/C>G/Large del, exhibited complete male virilisation (Prader 5). The remaining four affected female new-borns also exhibited the SW form, with two of them virilised as Prader 3 and the other two as Prader 4. Virilisation with clitoromegaly was also observed in one female, who presented premature adrenarche and carried the least severe p.Pro30Leu mutation. Conclusion: The frequency of the underlying mutations in our patients, with the classic form of CAH, varies but were quite similar to the ones reported in the Mediterranean region. Therefore, the identification of severe CYP21A2 defects in Cypriot patients and their comparison with the incidence and severity in different populations, will create a valuable diagnostic tool for genetic counseling in the classic form of CAH.

GnRH-dependent precocious puberty manifested at the age of 14 months in a girl with 47,XXX karyotype

This case report describes a 47,XXX girl who presented very early, at the age of 14 months, with signs of sexual precocity (breast and pubic hair development, menarche) and was finally diagnosed with GnRH dependent precocious puberty with no evidence of underlying central nervous system pathology. Molecular testing did not identify any genetic defect in any of the genes tested (KISS1, KISS1R, DLK1 and the intronless MKRN3). Though previous studies have shown a link between karyotype 47,XXX and precocious puberty, this is the youngest patient reported so far. Treatment with GnRH analog was commenced and proved to be effective, indicating a successful suppression of the hypothalamic-pituitary-ovarian axis.

Identification of a novel 15.5 kb SHOX deletion associated with marked intrafamilial phenotypic variability and analysis of its molecular origin

Haploinsufficiency of the short stature homeobox contaning SHOX gene has been shown to result in a spectrum of phenotypes ranging from Leri-Weill dyschondrosteosis (LWD) at the more severe end to SHOX-related short stature at the milder end of the spectrum. Most alterations are whole gene deletions, point mutations within the coding region, or microdeletions in its flanking sequences. Here, we present the clinical and molecular data as well as the potential molecular mechanism underlying a novel microdeletion, causing a variable SHOX-related haploinsufficiency disorder in a three-generation family. The phenotype resembles that of LWD in females, in males, however, the phenotypic expression is milder. The 15523-bp SHOX intragenic deletion, encompassing exons 3-6, was initially detected by array-CGH, followed by MLPA analysis. Sequencing of the breakpoints indicated an Alu recombination-mediated deletion (ARMD) as the potential causative mechanism.

Evidence of digenic inheritance in autoinflammation-associated genes

Familial Mediterranean fever (FMF) has traditionally been considered as a monogenic autosomal recessive disorder caused by mutations in the MEFV gene with highest incidence among Mediterranean populations. In a considerable number of patients with typical FMF, only one MEFV mutation was identified and the possibility that more than one autoinflammatory gene may be responsible for their disease was investigated. In the present study, an extensive search for possible mutations in three hereditary recurrent fever (HRF) genes was performed in 128 MEFV heterozygous Greek-Cypriots clinically diagnosed based on their phenotype with FMF-like disease from a previous study. Sequence analysis was performed for MVK, TNFRSF1A and NLRP3 genes which is also known to cause HRFs. In total, three patients were identified with heterozygous mutations and a second mutation in an autoinflammatory gene. Two patients carried a MEFV mutation and a NLRP3 mutation, and an additional third carried a MEFV mutation and a TNFRSF1A mutation. Patient 1 carried MEFV p.[Val726Ala] (NM_000243.2:c.2177T>C) and NLRP3 p.[Val198Met] (NM_001243133.1:c.592G>A) variants and patient 2 carried MEFV p.[Glu148Gln] (NM_000243.2:c.442G>C) variant which is of uncertain significance and NLRP3 p.[Arg176Trp] (NM_001243133.1:c.526C>T). Lastly, patient 3 was identified to carry MEFV p.[Met694Val] (NM_000243.2:c.2080A>G) and TNFRSF1A p.[Arg121Gln] (NM_001065.3:c.362G>A) variants. The results from this study indicate that screening of genes known to cause HRFs in patients already identified with a single MEFV mutation, can reveal quite rare but potentially causative mutational combinations at different loci. Such interaction provide further evidence for possible locus-locus interactions and phenotypes resulting from digenic inheritance.

Developing and evaluating rare disease educational materials co-created by expert clinicians and patients: the paradigm of congenital hypogonadotropic hypogonadism

Background

Patients with rare diseases face health disparities and are often challenged to find accurate information about their condition. We aimed to use the best available evidence and community partnerships to produce patient education materials for congenital hypogonadotropic hypogonadism (CHH) and the olfacto-genital (Kallmann) syndrome (i.e., CHH and defective sense of smell), and to evaluate end-user acceptability. Expert clinicians, researchers and patients co-created the materials in a multi-step process. Six validated algorithms were used to assess reading level of the final product. Comprehensibility and actionability were measured using the Patient Education Materials Assessment Tool via web-based data collection. Descriptive statistics were employed to summarize data and thematic analysis for analyzing open-ended responses. Subsequently, translation and cultural adaption were conducted by clinicians and patients who are native speakers.

Results

Co-created patient education materials reached the target 6^th grade reading level according to 2/6 (33%) algorithms (range: grade 5.9–9.7). The online survey received 164 hits in 2 months and 63/159 (40%) of eligible patients completed the evaluation. Patients ranged in age from 18 to 66 years (median 36, mean 39 ± 11) and 52/63 (83%), had adequate health literacy. Patients scored understandability at 94.2% and actionability at 90.5%. The patient education materials were culturally adapted and translated into 20 languages (available in Additional file 1).

Conclusions

Partnering with patients enabled us to create patient education materials that met patient- identified needs as evidenced by high end-user acceptability, understandability and actionability. The web-based evaluation was effective for reaching dispersed rare disease patients. Combining dissemination via traditional healthcare professional platforms as well as patient-centric sites can facilitate broad uptake of culturally adapted translations. This process may serve as a roadmap for creating patient education materials for other rare diseases.

Electronic supplementary material

The online version of this article (doi:10.1186/s13023-017-0608-2) contains supplementary material, which is available to authorized users.

CDKN2A and MC1R variants found in Cypriot patients diagnosed with cutaneous melanoma

The prevalence of genetic variants associated to cutaneous melanoma (CM) has never been determined within Cypriot melanomas. This study evaluates the frequency of variants in cyclin-dependent kinase inhibitor 2A (CDKN2A) and melanocortin-1 receptor (MC1R) in 32 patients diagnosed with CM. Other characteristics and risk factors were also assessed. CDKN2A p.Ala148Thr was detected in three of 32 patients, while the control group revealed no variations within CDKN2A. MC1R screening in 32 patients revealed the following variations: p.Val60Leu in 11 patients, p.Arg142His in four patients, p.Thr314Thr in one patient, p.Arg160Trp in one patient, p.Val92Met/p.Thr314Thr in one patient and p.Val92Met/p.Arg142His/p.Thr314Thr in one patient. The control group revealed only p.Val60Leu (in 10 of 45 individuals), which is frequently found in general populations. Two unrelated patients carried CDKN2A p.Ala148Thr in combination with MC1R p.Arg142His, suggesting digenic inheritance that may provide evidence of different gene variants acting synergistically to contribute for CM development. This study confirms the presence of CDKN2A and MC1R variants among Cypriot melanomas and supports existing evidence of a role for these variants in susceptibility to melanoma.

Variations in the 3'UTR of the CYP21A2 Gene in Heterozygous Females with Hyperandrogenaemia

Heterozygosity for CYP21A2 mutations in females is possibly related to increased risk of developing clinical hyperandrogenism. The present study was designed to seek evidence on the phenotype-genotype correlation in female children, adolescents, and women with CYP21A2 mutations and variants in the 3'UTR region of the gene. Sixty-six patients out of the 169 were identified as carriers of CYP21A2 mutations. Higher values of stimulated 17 hydroxyprogesterone (17-OHP) levels were found in the carriers of the p.Val281Leu mutation compared to the carriers of other mutations (mean: 24.7 nmol/l versus 15.6 nmol/l). The haplotype of the ^∗52C>T, ^∗440C>T, and ^∗443T>C in the 3'UTR was identical in all heterozygous patients with p.Val281Leu and the haplotype of the ^∗12C>T and ^∗52C>T was identical in all heterozygous patients with the p.Gln318^∗. In conclusion, hyperandrogenaemic females are likely to bear heterozygous CYP21A2 mutations. Carriers of the mild p.Val281Leu mutation are at higher risk of developing hyperandrogenism than the carriers of more severe mutations. The identification of variants in the 3'UTR of CYP21A2 in combination with the heterozygous mutation may be associated with the mild form of nonclassic congenital adrenal hyperplasia and reveal the importance of analyzing the CYP21A2 untranslated regions for the appropriate management of this category of patients.

A novel MC4R deletion coexisting with FTO and MC1R gene variants, causes severe early onset obesity

OBJECTIVE

Heterozygous mutations on the melanocortin-4-receptor gene (MC4R) are the most frequent cause of monogenic obesity. We describe a novel MC4R deletion in a girl with severe early onset obesity, tall stature, pale skin and red hair.

CASE REPORT

Clinical and hormonal parameters were evaluated in a girl born full-term by non-consanguineous parents. Her body mass index (BMI) at presentation (3 years) was 30 kg/m² (z-score: +4.5SDS). By the age of 5.2 years, she exhibited extreme linear growth acceleration and developed hyperinsulinemia.

METHODS

Direct sequencing of the MC4R, MC1Rand for the knownFTOsingle nucleotide polymorphism (SNP) rs9939609was performed for the patient and her family.

RESULTS

A novel heterozygous MC4R p.Met215del (c.643_645delATG) deletion was identified in the patient, her father and her brother, both of whom exhibited a milder phenotype. 3D structural dynamic simulation studies investigated the conformational changes induced by the p.Met215del. The patient and her mother were also found to be carriers of the obesity risk associated FTOrs9939609SNP. Finally, the identification of the known p.Arg160Trp MC1Rvariant in the patient accounts for the red hair and pale skin phenotypic features.

CONCLUSION

The p.Met215del causes global conformational and functional changes as it is localized at the alpha-helical transmembrane regions and the membrane spanning regions of the beta-barrel. This novel mutation produces a severe overgrowth phenotype that is apparent as from infancy and is progressive in childhood. The additional negative effect of environmental and unhealthy lifestyle habits as well as a possible co-interaction of FTOrs9939609 SNP may worsen the phenotype.

Genetic screening of non-classic CAH females with hyperandrogenemia identifies a novel CYP11B1 gene mutation

OBJECTIVE

Congenital adrenal hyperplasia (CAH) is an endocrine autosomal recessive disorder with various symptoms of diverse severity. Mild hyperandrogenemia is the most commonclinical feature in non-classic CAH patients and 95% of the cases are identified by mutations in the CYP21A2 gene. In the present study, the second most common cause for non-classic CAH (NC-CAH), 11β-hydroxylase deficiency due to mutations in the CYP11B1 gene, is investigated.

DESIGN

Screening of the CYP21A2 and CYP11B1 genes by direct sequencing was carried out for the detection of possible genetic defects in patients with suspected CAH.

RES ULTS

It wasobserved that CYP11B1 variants co-exist only in rare cases along with mutations in CYP21A2 in patients clinically diagnosed with CAH. A total of 23 NC-CAH female patients out of 75 were identified with only one mutation in the CYP21A2 gene. The novel CYP11B1 gene mutation, p.Val484Asp, was identified in a patient with CAH in the heterozygous state. The structural characterization of the novel p.Val484Asp was found to likely cause distortion of the surrounding beta sheet and indirect destabilization of the cavity that occurs on the opposite face of the structural elements, leading to partial impairment of the enzymatic activity.

CONCLUSIONS

CYP21A2 gene mutations are the most frequent genetic defects in cases of NC-CAH even when these patients are in the heterozygous state. These mutations have a diverse phenotype giving rise to a variable extent of cortisol synthesis impairment; it is also clear that CYP11B1 mutants are a rare type of defects causing CAH.

In silico analysis of a novel MKRN3 missense mutation in familial central precocious puberty

BACKGROUND

The onset of puberty is influenced by the interplay of stimulating and restraining factors, many of which have a genetic origin. Premature activation of the GnRH secretion in central precocious puberty (CPP) may arise either from gain-of-function mutations of the KISS1 and KISS1R genes or from loss-of-function manner mutations of the MKRN3 gene leading to MKRN3 deficiency.

OBJECTIVE

To explore the genetic causes responsible for CPP and the potential role of the RING finger protein 3 (MKRN3) gene.

DESIGN AND PATIENTS

We investigated potential sequence variations in the intronless MKRN3 gene by Sanger sequencing of the entire 507 amino acid coding region of exon 1 in a family with two affected girls presented with CPP at the age of 6 and 5·7 years, respectively.

RESULTS

A novel heterozygous g.Gly312Asp missense mutation in the MKRN3 gene was identified in these siblings. The imprinted MKRN3 missense mutation was also identified as expected in the unaffected father and followed as expected an imprinted mode of inheritance. In silico analysis of the altered missense variant using the computational algorithms Polyphen2, SIFT and Mutation Taster predicted a damage and pathogenic alteration causing CPP. The pathogenicity of the alteration at the protein level via an in silico structural model is also explored.

CONCLUSION

A novel mutation in the MKRN3 gene in two sisters with CPP was identified, supporting the fundamental role of this gene in the suppression of the hypothalamic GnRH neurons.

Genetic defects of the CYP21A2 gene in girls with premature adrenarche

OBJECTIVES

To seek evidence on the prevalence of CYP21A2 genetic defects and consequences in girls with premature adrenarche (PA).

METHODS

The study included 59 girls diagnosed with PA. Direct DNA sequencing and MLPA analysis were performed to identify mutations in CYP21A2 gene.

RESULTS

Twelve girls were diagnosed with non-classic congenital adrenal hyperplasia (NC-CAH) based on stimulated 17-hydroxyprogesterone (17-OHP) levels and the presence of two mutations in CYP21A2, 19 were heterozygotes. The most frequent mutations detected were the mild p.Val281Leu and p.Pro453Ser. Higher levels of mean stimulated 17-OHP were found in the carriers of the p.Val281Leu mutation. The detection rate for two CYP21A2 mutations was higher in girls with PA than in adult females with hyperandrogenemia in our studied population. A notable increased allelic frequency for the known p.Asn493Ser polymorphism was observed in the pool of the 28 girls with PA in whom no mutation was identified.

CONCLUSIONS

In girls with PA, the frequency of the underlying CYP21A2 genetic defects is similar to that observed in other populations. The carrier status is likely a contributing factor in the genotype-phenotype correlation in NC-CAH. However, polymorphisms and other genes may be implicated in the clinical manifestation of the disease.

Phenotypic variability of hyperandrogenemia in females heterozygous for CYP21A2 mutations

OBJECTIVES

The objective was to seek evidence on the prevalence and consequences of heterozygous CYP21A2 mutations in girls, adolescent, and adult females with clinical manifestation of androgen excess.

PATIENTS AND METHODS

The study included 64 girls diagnosed with premature adrenarche (PA) in childhood and 141 females with clinical hyperandrogenemia manifested in adolescence or adulthood. Direct DNA sequencing and multiplex ligation-dependent probe amplification analysis were used to identify mutations in the CYP21A2 gene.

RESULTS

(1) Thirty-four patients were diagnosed with nonclassical-congenital adrenal hyperplasia (NC-CAH) based on the 17-hydroxyprogesterone (17-OHP) levels and the presence of two mutations in CYP21A2 and therefore were excluded from the study, 66 were found to be heterozygotes and finally 105 had no identifiable mutations. The most frequent mutations among the carriers were the mild p.Val281 Leu and p.Qln318stop. Higher levels of mean stimulated 17-OHP were found in the carriers of the p.Val281 Leu. (2) A notable increased allelic frequency for the known p.Asn493 Ser polymorphism was observed in the pool of females with hyperandrogenemia in whom no mutation was identified. (3) In girls, who presented early with PA, 26.6% were diagnosed with NC-CAH and carried two mutations, 28.7% were identified as heterozygotes 43.7% had no identifiable genetic defect in the translated region of the CYP21A2 gene. On the contrary, in the group of 141 females with late onset hyperandrogenemia, the presence of 2 mutations was detected in 12%, 1 mutation in 33.4% and no mutation in 54.6%.

CONCLUSIONS

The carrier status for 21-OHD, may be an important factor in the variable phenotype of hyperandrogenism and may be a contributing factor for the early manifestation of the disease.

A report of 2 new cases of MODY2 and review of the literature: implications in the search for type 2 diabetes drugs

Glucokinase (GCK) acts as a glucose sensor and stimulates the release of insulin from pancreatic β-cells and any GCK gene mutations can lead to different forms of diabetes, such as GCK-monogenic diabetes of the young type 2 (MODY2), permanent neonatal diabetes and congenital hyperinsulinism. Many MODY2 causing mutations display a variation in the degree of severity, ranging from mild dietary-restricted forms to more detrimental presentation requiring insulin replacement. The present study reviews known and two novel GCK mutations in terms of molecular perturbation of the GCK atomic structure but also emphasizes the inactivating and activating properties of the GCK as treatment for T2DM. In silico analysis demonstrated that the newly discovered mutation p.Arg447Pro causes structural conformational changes that lead to the destabilization of the functional properties of the protein resulting in the reduction of glucose and MgATP2- affinity. The novel p.Glu440Stop nonsense mutation on the other hand inactivates the cytoplasmic enzymatic activity of the protein as it is responsible for the loss of the C-terminal end of the polypeptide that includes vital glucose-releasing residues. Based on the in silico models of existing structural data we identified several classes of GCK mutations and discuss their relation to disease outcome. GCK has a central role in controlling body glucose homeostasis and therefore is considered an outstanding drug target for developing new antidiabetic therapies using small molecular activators (GKAs). This study emphasizes the importance in understanding how inactivating and activating GCK mutations affect the mechanistic properties of this glucose sensor. Such information can become the basis for drug discovery of therapeutic compounds and the treatment of T2DM by targeting the GCK allosteric activator site.

High carrier frequency of 21-hydroxylase deficiency in Cyprus

Congenital adrenal hyperplasia (CAH) due to 21-hydroxylase deficiency (21-OHD) is a common autosomal recessive disorder caused by mutations in the CYP21A2 gene. The carrier frequency of CYP21A2 mutations has been estimated to be 1:25 to 1:10 on the basis of newborn screening. The main objective of this study was to determine the carrier frequency in the Cypriot population of mutations in the CYP21A2 gene. Three hundred unrelated subjects (150 males and 150 females) from the general population of Cyprus were screened for mutations in the CYP21A2 gene and its promoter. The CYP21A2 genotype analysis identified six different mutants and revealed a carrier frequency of 9.83% with the mild p.Val281Leu being the most frequent (4.3%), followed by p.Qln318stop (2.5%), p.Pro453Ser (1.33%), p.Val304Met (0.83%), p.Pro482Ser (0.67%) and p.Met283Val (0.17%). The notable high CYP21A2 carrier frequency of the Cypriot population is one of the highest reported so far by genotype analysis. Knowledge of the mutational spectrum of CYP21A2 will enable to optimize mutation detection strategy for genetic diagnosis of 21-OHD not only in Cyprus, but also the greater Mediterranean region.

A family with Camurati-Engelman disease: the role of the missense p.R218C mutation in TGFbeta1 in bones and endocrine glands

OBJECTIVES

Camurati-Engelmann disease (CED) is a rare form of progressive diaphyseal dysplasia as a result of mutations in the transforming growth factor gene TGFbeta1 on chromosome 19q13.1-q13.3. Endocrine complications such as osteoporosis, vitamin D deficiency, delayed puberty, and hypogonadotrophic hypogonadism may be present.

METHODS

Genetic analysis of the TGFbeta1 gene revealed a heterozygous missense mutation p.R218C in exon 4 of chromosome 19q13.1-q13.3 in a 14-year-old girl who presented with typical symptoms of CED, hyperprolactinaemia, and menstrual irregularity.

RESULTS

The patient responded well to prednisone 5 mg/kg/day, as well as calcium and vitamin D supplements.

CONCLUSIONS

The role of p.R218C in TGFbeta1 on the mechanism of the disease, and the complications of it in bones and endocrine glands, remains unclear. Early recognition as well as a detailed understanding of the pathogenesis of the disease are important for future treatment options and a better quality of life of such patients.

A family with Camurati-Engelman disease. The role of the missense p.R218C mutation in TGFB1 in bones and endocrine glands

OBJECTIVES

Camurati-Engelmann disease (CED) is a rare form of progressive bone dysplasia due to mutations in the transforming factor gene TGFB1 on chromosome 19q13.1-q13.3. Endocrine complications such as osteoporosis, vitamin D deficiency, delayed puberty and hypogonadotrophic hypogonadism may be present.

METHODS AND RESULTS

Genetic analysis of the TGFB1 gene revealed a heterozygous missense mutation p.R218C in exon 4 of chromosome 19q13.1-q13.3 in a 14-year-old girl who presented with typical symptoms of CED, hyperprolactinaemia and menstrual irregularity. The patient responded well to prednisone 5 mg/kg per day as well as calcium and vitamin D supplements.

CONCLUSIONS

The role of p.R218C in TGFB1 on the mechanism of the disease itself and the complications of it in bones and endocrine glands remain unclear. Early recognition as well as a detailed understanding of the pathogenesis of the disease is important for future treatment options and better quality of life of such patients.

Genetic defects in the cyp21a2 gene in heterozygous girls with premature adrenarche and adolescent females with hyperandrogenemia

Congenital adrenal hyperplasia (CAH) is a common autosomal recessive disorder primarily caused by mutants in the CYP21A2 gene. Heterozygosity for CYP21A2 mutations in females increases their risk of clinically manifesting hyperandrogenism and the present study was designed to seek evidence on the prevalence and consequences of heterozygous CYP21A2 mutations in children with premature adrenarche and adolescents with hyperandrogenemia. The hormonal response to ACTH was evaluated in 17 girls with clinical signs of premature adrenarche and 17 adolescent females with hyperandrogenemia, along with direct DNA sequencing and MLPA analysis for mutations in the CYP21A2 gene. The suspicion of heterozygote state was based on the median plasma 17-OHP before and 60 minutes after ACTH stimulation. All 34 patients were identified as carriers of CYP21A2 mutations. The most frequent mutations among this cohort of carriers were the mild p.V281L (52.9%), followed by p.Q318stop (20.6%), p.V304M (8.9%), p.P482S (5.9%), p.P453S (5.9%), large deletion/conversion exons 1-4 (2.9%) and large deletion/conversion exons 6-8 (2.9%). Higher values of stimulated 17-OHP levels were found in the carriers of the p.V281L mutation compared with carriers of other mutations (mean=21.9 nmol/L vs 17.0 nmol/L). This finding supports the already identified notion that carriers of the mild p.V281L are at higher risk for hyperandrogenism than carriers of severe mutations.

IN CONCLUSION

a. Females with premature adrenarche and hyperandrogenemia are likely to bear heterozygous CYP21A2 mutations, therefore systematic evaluation of 17-OHP values in combination with the molecular testing of CYP21A2 gene is beneficial, b. carriers of the mild p.V281L, are at higher risk of androgen excess compared to carriers of other types of mutations.

Effects of growth hormone on heart structure and function in adolescence

Until recently, growth hormone (GH) and insulin-like growth factor 1 (IGF-1) were considered to control only linear growth. Apart from growth effect, GH has additional important physiological functions in the human body influencing several metabolic processes, body composition, muscle strength, and bone mineral density. In adolescence, where the majority of these physiological functions reach a zenith, GH plays a crucial role. The ability of GH to trigger cardiac muscle growth by direct and indirect effects plays a pivotal role in the physiology of the heart. Patients with childhood or adulthood onset of GH deficiency are exposed to increased risk for cardiovascular morbidity. GH treatment may have beneficial effect on the cardiovascular system in GH deficient adolescents. On the other hand discontinuation of GH treatment in these patients may result in the accumulation of relevant cardiovascular risk factors such as increase in body and abdominal fat and LDL and total cholesterol concentrations. No potential adverse cardiac effects of GH therapy have been so far demonstrated in short stature patients with normal GH secretion. Nevertheless, no evidence of heart hypertrophy or cardiomypathy has been documented in adolescents with GH excess has been reported in adults. Nonetheless, normalization of GH and IGF-1 levels in such patients is essential in order to arrest cardiovascular disease later in life.