Oligogenic Inheritance Underlying Incomplete Penetrance of PROKR2 Mutations in Hypogonadotropic Hypogonadism.

The role of the prokineticin 2 pathway in human reproduction, olfactory bulb morphogenesis, and gonadotropin-releasing hormone secretion is well established. Recent studies have highlighted the implication of di/oligogenic inheritance in this disorder. In the present study, we aimed to identify the genetic mechanisms that could explain incomplete penetrance in hypogonadotropic hypogonadism (HH). This study involved two unrelated Tunisian patients with HH, which was triggered by identifying a homozygous p.(Pro290Ser) mutation in the PROKR2 gene in a girl (HH1) with Kallmann syndrome (KS). The functional effect of this variant has previously been well demonstrated. Unexpectedly, her unaffected father (HH1P) and brother (HH1F) also carried this genetic variation at a homozygous state. In the second family, we identified a heterozygous p.(Lys205del) mutation in PROKR2, both in a male patient with normosmic idiopathic IHH (HH12) and his asymptomatic mother. Whole-exome sequencing in the three HH1 family members allowed the identification of additional variants in the prioritized genes. We then carried out digenic combination predictions using the oligogenic resource for variant analysis (ORVAL) software. For HH1, we found the highest number of disease-causing variant pairs. Notably, a CCDC141 variant (c.2803C > T) was involved in 18 pathogenic digenic combinations. The CCDC141 variant acts in an autosomal recessive inheritance mode, based on the digenic effect prediction data. For the second patient (HH12), prediction by ORVAL allowed the identification of an interesting pathogenic digenic combination between DUSP6 and SEMA7A genes, predicted as "dual molecular diagnosis." The SEMA7A variant p.(Glu436Lys) is novel and predicted as a VUS by Varsome. Sanger validation revealed the absence of this variant in the healthy mother. We hypothesize that disease expression in HH12 could be induced by the digenic transmission of the SEMA7A and DUSP6 variants or a monogenic inheritance involving only the SEMA7A VUS if further functional assays allow its reclassification into pathogenic. Our findings confirm that homozygous loss-of-function genetic variations are insufficient to cause KS, and that oligogenism is most likely the main transmission mode involved in Congenital Hypogonadotropic Hypogonadism.

Clinical lessons learned in constitutional hypopituitarism from two decades of experience in a large international cohort.

CONTEXT: The international GENHYPOPIT network collects phenotypical data and screens genetic causes of non-acquired hypopituitarism. AIMS: To describe main phenotype patterns and their evolution through life. DESIGN: Patients were screened according to their phenotype for coding sequence variations in 8 genes: HESX1, LHX3, LHX4, PROP1, POU1F1, TBX19, OTX2 and PROKR2. RESULTS: Among 1213 patients (1143 index cases), the age of diagnosis of hypopituitarism was congenital (24%), in childhood (28%), at puberty (32%), in adulthood (7.2%) or not available (8.8%). Noteworthy, pituitary hormonal deficiencies kept on evolving during adulthood in 49 of patients. Growth Hormone deficiency (GHD) affected 85.8% of patients and was often the first diagnosed deficiency. AdrenoCorticoTropic Hormone deficiency rarely preceded GHD, but usually followed it by over 10 years. Pituitary Magnetic Resonance Imaging (MRI) abnormalities were common (79.7%), with 39.4% pituitary stalk interruption syndrome (PSIS). The most frequently associated extrapituitary malformations were ophthalmological abnormalities (16.1%). Prevalence of identified mutations was 7.3% of index cases (84/1143) and 29.5% in familial cases (n = 146). Genetic analysis in 449 patients without extrapituitary phenotype revealed 36 PROP1, 2 POU1F1 and 17 TBX19 mutations. CONCLUSION: This large international cohort highlights atypical phenotypic presentation of constitutional hypopituitarism, such as post pubertal presentation or adult progression of hormonal deficiencies. These results justify long-term follow-up, and the need for systematic evaluation of associated abnormalities. Genetic defects were rarely identified, mainly PROP1 mutations in pure endocrine phenotypes.

Association of apolipoprotein A5 gene variants with metabolic syndrome in Tunisian population.

AIM OF THE STUDY: APOA5 has been linked to metabolic syndrome (MetS) or its traits in several populations. In North Africa, only the Moroccan population was investigated. Our aim is to assess the association between APOA5 gene polymorphisms with the susceptibility to MetS and its components in the Tunisian population. MATERIALS AND METHODS: A total of 594 participants from the Tunisian population were genotyped for two polymorphisms rs3135506 and rs651821 located in APOA5 gene using KASPar technology. Statistical analyses were performed using R software. RESULTS: The SNP rs651821 increased the risk of MetS under the dominant model (OR=1.91 [1.17-3.12], P=0.008) whereas the variant rs3135506 was not associated with MetS. After stratification of the cohort following the sex, only the variant rs651821 showed a significant association with MetS among the women group. The influence of the geographic origin of the studied population on the genotype distribution of APOA5 variants showed that the variant rs651821 was significantly associated with MetS only for the Northern population. The association analyses of the variants rs651821 and rs3135506 with different quantitative traits of MetS showed a significant association only between the variant rs3135506 and triglycerides levels. CONCLUSION: This is the first study reporting the association of APOA5 gene variants with MetS in Tunisia. Our study emphasizes the role of APOA5 variants in the regulation of the triglycerides blood levels. Further studies are needed to confirm the clinical relevance of these associations and to better understand the physiopathology of the MetS.

Gender-specific associations of genetic variants with metabolic syndrome components in the Tunisian population.

AIM OF THE STUDY: Recent genome-wide association studies (GWASs) have identified many genetic variants associated with metabolic syndrome (MetS). However, their contribution to MetS in ethnic groups in Tunisia is largely unexplored. In this study, we aim to examine the associations of related loci with a risk of metabolic syndrome in a sample of Tunisians. MATERIALS AND METHODS: Overall seven polymorphisms rs7265718, rs10401969, rs762861, rs12310367, rs1562398, rs2059807, rs4420638 located at C20orf152, CILP2, LRPAP1, ZNF664, KLF14, INSR, APOE, respectively, were analyzed in 356 samples from the Tunisian population. Anthropometric and biochemical parameters were assessed. Metabolic syndrome was defined according to the International Diabetes Federation (IDF). RESULTS: We find that LRPAP1-rs762861 C allele increases susceptibility to MetS (OR = 1.39, 95% CI = 0.99-1.95, p = 0.041). Separate analysis in men and women revealed the association of rs762861 among females (OR = 1.6, 95% CI = 1.057-2.41, p = 0.021), but not among males (OR = 0.953, 95% CI = 0.51-1.78, p = 0.882). ZNF664-rs12310367 was also found to be associated with body mass index (BMI) in women (p = 0.01) and not in men (p = 0.18). KLF14-rs1562398 was significantly correlated with impaired fasting glucose (p = 0.004) only in men. CONCLUSIONS: Our results reveal new candidate genes for MetS in the Tunisian population and suggest that the genetic basis of this syndrome is gender dependent. Further studies are necessary to understand why these associations differ between males and females.

Association of rs9939609 Polymorphism with Metabolic Parameters and FTO Risk Haplotype Among Tunisian Metabolic Syndrome.

BACKGROUND: Variants in the fat mass and obesity-associated (FTO) gene are associated with obesity and type 2 diabetes mellitus. AIM OF THE STUDY: This study aims to assess the association of the rs9939609 variant and haplotypes in FTO gene with metabolic syndrome (MetS) components in a Tunisian population sample. METHODS: A total of 685 Tunisian subjects were genotyped for the rs9939609T>A using TaqMan allelic discrimination assay. Two variants rs1421085T>C and rs8057044A>G already genotyped in a previous study were used to test haplotype association of the FTO gene. RESULTS: Genotype distribution of the variant rs9939609 was different between MetS and controls (P = 0.017). Individuals carrying TA genotypes had a significantly increased risk independently of body mass index or age (P = 0.009). The variant rs9939609 was also associated with impaired fasting glucose (IFG) (P = 0.002). Among the eight haplotypes in the population, the haplotype GCA was significantly associated with a higher risk of developing the MetS, higher systolic blood pressure, and higher levels of fasting glucose and triglycerides (TGs) in the total sample and females, separately. Separate analysis by gender revealed a protective haplotype TGT among women (P = 0.023). CONCLUSIONS: FTO haplotypes have a strong influence on blood pressures and TG and IFG levels. These findings provide evidence that FTO gene may play a critical role in leading to MetS in Tunisian population.

Association of genetic variants in the FTO gene with metabolic syndrome: A case-control study in the Tunisian population.

AIMS: Variants in the fat mass and obesity-associated gene (FTO) are associated with obesity and type 2 diabetes. However, the association of FTO variants in the MENA (Middle East and North Africa) region with MetS is largely unknown. In this study, we aimed to investigate the association of FTO gene with MetS and its components in Tunisian population. METHODS: Two variants in the FTO gene were genotyped: rs1421085 T>C and rs8057044 A>G in cases and controls from Tunisian population. Anthropometric and biochemical parameters were assessed. Metabolic syndrome was defined according to the International Diabetes Federation (IDF). RESULTS: The FTO rs1421085 variant conferred an increased risk to MetS (OR=1.61, 95% CI=1.14-2.26, P=0.024) that was abolished when adjusted for fasting plasma glucose (FPG), suggesting that the association may be due to variation in FPG levels. Indeed, this variant was associated to FPG (OR = 1.7, 95% CI=1.23-2.44, P=0.002) independently from BMI or age. The second polymorphism rs8057044 was associated with high blood pressure levels (OR=1.45, 95% CI=1.06-1.99, P=0.019). CONCLUSIONS: This is the first study highlighting the association between FTO gene variants and MetS in Tunisian population. These findings provide evidence that FTO gene may play a critical role in leading to MetS in Tunisian population.

Cytogenetic abnormalities in Tunisian women with premature ovarian failure.

To identify the distribution of chromosome abnormalities among Tunisian women with premature ovarian failure (POF) referred to the department of Cytogenetic at the Pasteur Institute of Tunis (Tunisia), standard cytogenetic analysis was carried out in a total of 100 women younger than 40 affected with premature ovarian failure. We identified 18 chromosomal abnormalities, including seven X-numerical anomalies in mosaic and non-mosaic state (45,X; 47,XXX), four sex reversal, three X-structural abnormalities (terminal deletion and isochromosomes), one autosomal translocation and one supernumerary marker. The overall prevalence of chromosomal abnormalities was 18% in our cohort. X chromosome aneuploidy was the most frequent aberration. This finding confirms the essential role of X chromosome in ovarian function and underlies the importance of cytogenetic investigations in the routine management of POF.

A Tunisian patient with two rare syndromes: triple a syndrome and congenital hypogonadotropic hypogonadism.

BACKGROUND/AIMS: The coexistence of triple A syndrome (AAAS) and congenital hypogonadotropic hypogonadism (CHH) has so far not been reported in the literature. This study aimed to characterize at the clinical and genetic level one patient presenting an association of AAAS and CHH in order to identify causal mutations. METHODS: Clinical and endocrinal investigations were performed and followed by mutational screening of candidate genes. RESULTS: At the age of 18, the patient presented sexual infantilism, a micropenis and gynecomastia. No mutation was revealed in GnRHR, TACR3/TAC3, PROK2/PROKR2 and PROP1 genes, except a homozygous intronic variation (c.244 + 128C>T; dbSNP: rs350129) in the KISS1R gene, which is likely nondeleterious. A homozygous splice-donor site mutation (IVS14 + 1G>A) was found in the AAAS gene. This mutation, responsible for AAAS, is a founder mutation in North Africa. CONCLUSION: This is the first report on a Tunisian patient with the coexistence of AAAS and CHH. The diagnosis of CHH should be taken in consideration in patients with Allgrove syndrome and who carry the IVS14 + 1G>A mutation as this might challenge appropriate genetic counseling.

[Continuous glucose monitoring in glimipiride plus metformin treated type 2 diabetic patients during the month of Ramadan]. / Enregistrement continu du glucose pendant Ramadan chez des diabétiques de type 2 sous glimépiride et metformine.

BACKGROUND: Fasting during Ramadan may be a cause of poor glycaemic control in diabetic patients. AIM: To assess glucose excursions during Ramadan by using a continuous glucose monitoring system (CGMS). METHODS: The interstitial glucose level was recorded over 72 hours during Ramadan and three months later, in five type 2 diabetic patients, aged 56 ± 5, treated with glimepiride and metformin. RESULTS: During Ramadan, four patients experienced at least one episode of low glucose level (<0.7 g/l) during the monitoring. The frequency of these episodes was 0.6 episode/d with an average duration of 36 mn / d. These episodes occurred in the morning in half of the cases and in the hour before breaking the fast in 37.5 % of the cases. Four patients experienced at least one episode of high glucose level (>1.8 g/l), with an average duration of 403 mn /d and with a frequency of two episodes /d. More than half episodes (53) occurred after the breaking of the fast. After Ramadan, CGM records showed at least one episode of low glucose in two patients with an average duration of 58 mn /d and a frequency of 1.3 episodes/d. Three patients experienced at least one episode of high glucose level with an average duration of 525 mn /d and a frequency of 1.46 episodes/day. CONCLUSION: The blood glucose profile of our patients during Ramadan is characterized by important glycaemic excursions.

Hypocalcaemia due to hypoparathyroidism in ß-thalassemia major. A study of a new case.

AIM: To report a new case of hypoparathyroidism in a child with ß-thalassemia major CASE: We report a case of a 17-year-old Tunisian girl with transfusion-dependent thalassemia major presented with paresthesia and pubertal delay. Laboratory investigations showed hypocalcaemia and hyperphosphatemia. Parathyroid hormone level was low (2 ng/l, normal range: 12-72 ng/l) than expected for the degree of hypocalcaemia. Serum ferritin concentration was 1770ng/ml. The patient was started on oral daily calcium supplementation, Alfa calciferol and intensive iron chelation therapy. Follow-up after 6 and 12 months revealed normal Calcium and ECG showed QT interval within normal range. CONCLUSION: Investigating calcium homeostasis at regular intervals and early management of any abnormality can preclude the occurrence of complications.

[Renal failure in Tunisian patients with type 2 diabetes: frequency and related factors]. / L'insuffisance rénale chez des diabétiques de type 2 Tunisiens hospitalises: frequence et fateurs associés.

BACKGROUND: Frequent screening of renal failure and good glycaemic control in diabetic patients can avoid this severe complication. AIM: To evaluate the frequency of renal failure and the associated risk factors among type 2 diabetic Tunisian in-patients. Glomerular filtration rate was estimated using the Cockcroft-Gault formula. Renal failure was diagnosed on figure of glomerular filtration rate inferior than 60 ml/min. RESULTS: Six hundred eighty-nine patients were included. The sex ratio was 0.65. The mean age was 60 ± 11 years. The frequency of renal failure was 19.8% (137 patients) with dominance of a moderate form defined by a glomerular filtration rate between 30 and 59 ml/min (82.5% of patients). Patients with renal failure were older and less obese than diabetic patients without this complication (p<0.00001 and 0.02 respectively). The duration of both diabetes and hypertension was higher in presence of renal failure (p=0.0001 and p<0.001 respectively). Patients with renal failure had more often hypertension and dyslipidemia than patients with normal renal function (p<0.001 and p=0.01 respectively). A personal history of severe retinopathy treated by laser, of coronary disease or of stroke was significantly associated to renal failure (p=0.002, p<0.0001 and p=0.001 respectively). CONCLUSION: The frequency of renal failure observed in Tunisian patients diagnosed with type 2 diabetes is high. Hypertension and dyslipidemia should be carefully treated to prevent or delay the evolution to the renal failure.

A comparative phenotypic study of kallmann syndrome patients carrying monoallelic and biallelic mutations in the prokineticin 2 or prokineticin receptor 2 genes.

CONTEXT: Both biallelic and monoallelic mutations in PROK2 or PROKR2 have been found in Kallmann syndrome (KS). OBJECTIVE: The objective of the study was to compare the phenotypes of KS patients harboring monoallelic and biallelic mutations in these genes. DESIGN AND PATIENTS: We studied clinical and endocrine features that reflect the functioning of the pituitary-gonadal axis, and the nonreproductive phenotype, in 55 adult KS patients (42 men and 13 women), of whom 41 had monoallelic mutations and 14 biallelic mutations in PROK2 or PROKR2. RESULTS: Biallelic mutations were associated with more frequent cryptorchidism (70% vs. 34%, P < 0.05) and microphallus (90% vs. 28%, P < 0.001) and lower mean testicular volume (1.2 +/- 0.4 vs. 4.5 +/- 6.0 ml; P < 0.01) in male patients. Likewise, the testosterone level as well as the basal FSH level and peak LH level under GnRH-stimulation were lower in males with biallelic mutations (0.2 +/- 0.1 vs. 0.7 +/- 0.8 ng/ml; P = 0.05, 0.3 +/- 0.1 vs. 1.8 +/- 3.0 IU/liter; P < 0.05, and 0.8 +/- 0.8 vs. 5.2 +/- 5.5 IU/liter; P < 0.05, respectively). Nonreproductive, nonolfactory anomalies were rare in both sexes and were never found in patients with biallelic mutations. The mean body mass index of the patients (23.9 +/- 4.2 kg/m(2) in males and 26.3 +/- 6.6 kg/m(2) in females) did not differ significantly from that of gender-, age-, and treatment-matched KS individuals who did not carry a mutation in PROK2 or PROKR2. Finally, circadian cortisol levels evaluated in five patients, including one with biallelic PROKR2 mutations, were normal in all cases. CONCLUSION: Male patients carrying biallelic mutations in PROK2 or PROKR2 have a less variable and on average a more severe reproductive phenotype than patients carrying monoallelic mutations in these genes. Nonreproductive, nonolfactory clinical anomalies associated with KS seem to be restricted to patients with monoallelic mutations.

Molecular basis of pituitary development defects.

UNLABELLED: Over the last twenty years, the progress made in molecular biology have led to the identification of many transcription factor genes, whose mutations has been reported as causes of familial hypopituitarism. AIM: Based on a literature review, this study is intending to highlight the role of some transcription factors in the development of the anterior pituitary gland and to analyse the involvement of their dysfunction in some cases of congenital hypopituitarism. METHODS: Litterature review. RESULTS: These transcription factors are nuclear proteins expressed specifically in certain target cells, in order to control genes expression. Their role is fundamental in embryonic and foetal development, and particularly in pituitary ontogenesis. Together, they direct the formation of anterior pituitary gland, the differentiation, the expansion and the definitive function of the five pituitary cell types. In this report, after introducing the different stages of anterior pituitary development and differentiation of its cell lines, we will briefly highlight the clinical phenotypes associated with alterations of different transcription factor genes in both murine models and humans.

[Imaging diagnosis of an unilateral painful ophtalmoplegia]. / Diagnostic radiologique d'une ophtalmoplegie douloureuse unilaterale.

The ophtalmoplegia may be due to several lesions and the diagnosis is made by imaging modalities. We report the case of a giant aneurysm of the wright intracavernous internal carotid artery revealed by painful ophtalmoplegia with subarachnoid haemorrhage. The diagnosis was made by magnetic resonance imaging and angiography.