Objective: Nicotinamide nucleotide transhydrogenase (NNT), one of the several genes recently discovered in familial glucocorticoid deficiencies (FGD), is involved in reactive oxygen species detoxification, suggesting that extra-adrenal manifestations may occur, due to the sensitivity to oxidative stress of other organs rich in mitochondria. Here, we sought to identify NNT mutations in a large cohort of patients with primary congenital adrenal insufficiency without molecular etiology and evaluate the degree of adrenal insufficiency and onset of extra-adrenal damages. Methods: Sanger or massive parallel sequencing of NNT and patient monitoring. Results: Homozygous or compound heterozygous NNT mutations occurred frequently (26%, 13 unrelated families, 18 patients) in our cohort. Seven new mutations were identified: p.Met337Val, p.Ala863Glu, c.3G>A (p.Met1?), p.Arg129*, p.Arg379*, p.Val665Profs*29 and p.Ala704Serfs*19. The most frequent mutation, p.Arg129*, was found recurrently in patients from Algeria. Most patients were diagnosed belatedly (8-18 months) after presenting severe hypoglycemia; others experiencing stress conditions were diagnosed earlier. Five patients also had mineralocorticoid deficiency at onset. One patient had congenital hypothyroidism and two cryptorchidism. In follow-up, we noticed gonadotropic and genitalia impairments (precocious puberty, testicular inclusions, interstitial Leydig cell adenoma, azoospermia), hypothyroidism and hypertrophic cardiomyopathy. Intrafamilial phenotype heterogeneity was also observed. Conclusions: NNT should be sequenced, not only in FGD, but also in all primary adrenal insufficiencies for which the most frequent etiologies have been ruled out. As NNT is involved in oxidative stress, careful follow-up is needed to evaluate mineralocorticoid biosynthesis extent, and gonadal, heart and thyroid function.

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BackgroundCohen syndrome is a rare autosomal recessive developmental disorder that comprises variable clinical features counting developmental delay, pigmentary retinopathy, myopia, acquired microcephaly, truncal obesity, joint hypermobility, friendly disposition and intermittent neutropenia. VPS13B (vacuolar protein sorting 13, yeast, homologue of B) gene is the only gene responsible for Cohen Syndrome, causative mutations include nonsense, missense, indel and splice-site variants. The integrity of the Golgi apparatus requires the presence of the peripheral membrane protein VPS13B that have an essential function in intracellular protein transport and vesicle-mediated sorting.Case presentationIn this study, we performed whole exome sequencing (WES) in a Tunisian family with two young cases having developmental delay, hypotonia, autism spectrum disorder, ptosis and thick hair and eyebrows. The proposita presented also pigmentory retinopathy. Compound heterozygous mutation in VPS13B gene was detected by WES. This mutation inherited from healthy heterozygous parents, supports an unpredictable clinical diagnosis of Cohen Syndrome. The proband’s phenotype is explained by the presence of compound heterozygous mutations in the VPS13B gene. This finding refined the understanding of genotype-phenotype correlation.ConclusionsThis is the first report of a Tunisian family with Cohen syndrome mutated in the VPS13B gene.

Dyskeratosis congenital (DC) is the first genetic syndrome described among telomeropathies. Its classical phenotype is characterized by the mucocutaneous triad of reticulated pigmentation of skin lace, nail dystrophy and oral leukoplakia. The clinical presentation, however, is heterogeneous and serious clinical complications include bone marrow failure, hematological and solid tumors. It may also involve immunodeficiencies, dental, pulmonary and liver disorders, and other minor complication. Dyskeratosis congenita shows marked genetic heterogeneity, as at least 14 genes are responsible for the shortening of telomeres characteristic of this disease. This review discusses clinical characteristics, molecular genetics, disease evolution, available therapeutic options and differential diagnosis of dyskeratosis congenita to provide an interdisciplinary and personalized medical assessment that includes family genetic counseling.

Background Karyomegalic interstitial nephritis (KIN) is a rare disease entity first described by Burry in 1974. The term KIN was introduced by Mihatsch et al. in 1979. KIN is characterized by chronic tubulointerstitial nephritis associated with enlarged tubular epithelial cell nuclei, which leads to a progressive decline of renal function. The prevalence of this disease is less than 1% of all biopsies, and its pathogenesis is unclear. KIN results from mutations in FAN1 (FANCD2/FANCI-Associated Nuclease 1), a gene involved in the DNA damage response pathway, particularly in the kidney. In this study, we report two Tunisian consanguineous families with KIN caused by mutations in the FAN1 gene. Methods Direct sequencing of the coding regions and flanking intronic sequences of the FAN1 gene was performed in three affected members. Three prediction programs (Polyphen-2 software, SIFT, and MutationTaster) were used to predict the functional effect of the detected variations. Results Two causative frameshift variants in the FAN1 gene were identified in each family: The previously described frameshift mutation c.2616delA (p.Asp873ThrfsTer17) and a novel mutation c.2603delT (p.Leu868ArgfsTer22) classified as "pathogenic" according to the American College of Medical Genetics and Genomics (ACMG) guidelines. Conclusion To our best knowledge, this is the first Tunisian study involving familial cases of KIN with mutations in the FAN1 gene. We hypothesize that these findings can expand the mutational spectrum of KIN and provide valuable information on the genetic cause of KIN.

Donohue syndrome (DS) is a rare and lethal autosomal recessive disease caused by mutations in the insulin receptor (INSR) gene, manifesting marked insulin resistance, severe growth retardation, hypertrichosis, and characteristic dysmorphic features. We describe a new case of Donohue syndrome born at 37 weeks' gestation of unrelated parents and presented with intra-uterine growth retardation, nipple hypertrophy, macropenis, distended abdomen, hirsutism and dysmorphic features. The clinical course showed failure to thrive, and episodes of alternating hypoglycemia and hyperglycemia. Laboratory tests revealed direct hyperbilirubinemia. The diagnosis of Donohue syndrome was established based on the above clinical characteristics and determination of the INSR mutation. He was found to have homozygous nonsense mutation c. 2270 C>T (Arg924X) at exon 14 of the INSR gene. He later developed enterocolitis and died at 3 months old. Prenatal diagnosis was performed for the family via chorionic villous biopsy. We try to explain gastrointestinal dysfunction seen in our patient.

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