RESUMO
Background: Non-syndromic combined pituitary hormone deficiency (CPHD) occurs due to defects in transcription factors that govern early pituitary development and the specification of hormone-producing cells. The most common mutations are in the Prophet of Pit-1 (ProP1) gene. This work aims to (1) report findings of genetic analyses of Tunisian patients with non-syndromic CPHD and (2) describe their phenotype patterns and their evolution through life. Methods: Fifteen patients from twelve unrelated families with variable clinical phenotypes were included after excluding autoimmune and acquired forms of non-syndromic CPHD. Detailed pedigree charts and auxological, hormonal, radiological, and therapeutic details were recorded. Sanger sequencing was performed, and sequences were analyzed with a specific focus on coding and splice site regions of the ProP1 gene. Retained variants were classified using several in silico pathogenicity prediction tools and the VarSome platform. Results: We identified the common p.Arg73Cys mutation in seven patients from four unrelated pedigrees. We found a novel homozygous mutation (c.340C>T) in one sporadic case. This mutation generates a truncated ProP1 protein, predicted to be non-functional, lacking the last 112 codons (p.(Gln114Ter)). We confirmed by polymerase chain reaction (PCR) the absence of large exon deletions or insertions in the remaining sporadic patients (7/8). Conclusions: We report two mutations {one newly identified [p.(Gln114Ter)] and one previously reported (p.Arg73Cys)} in five unrelated Tunisian families with non-syndromic CPHD. This work is of clinical importance as it reports the high frequency of the p.Arg73Cys mutation in Tunisian CPHD families. Our study also illuminated the involvement of novel gene(s) in the emergence of non-syndromic CPHD.
RESUMO
PURPOSE: Congenital hypogonadotropic hypogonadism (CHH) is a rare genetic disorder mostly characterized by gonadotropins release and/or action deficiencies. Both isolated (idiopathic hypogonadotropic hypogonadism) and syndromic (Kallmann) forms are identified depending on the olfactory ability. Clinical and genetic heterogeneities of CHH have been widely explored, thus improving our understanding of the disease's pathophysiology. This work aims to (1) provide a detailed clinical and hormonal description of normosmic CHH patients and (2) identify the mutation linked to the studied phenotype. PARTICIPANTS AND METHODS: We investigated three affected patients with normosmic CHH, belonging to a consanguineous Tunisian family. Patients underwent an insulin-induced hypoglycemia test. We performed whole exome sequencing to identify the causal mutation. RESULTS: At first diagnosis, a total gonadotropic deficiency was identified in all patients. The insulin-induced hypoglycemia test has also revealed a reduced cortisol secretion and complete growth hormone deficiency. At 20.8 years, one female exhibited a spontaneous recovery of the hypothalamic-pituitary-adrenal axis function, unlike her affected siblings who still depend on corticosteroid replacement therapy. Herein, we identified a novel homozygous nonstop mutation (c.1195T>C) in KISS1R gene in all affected subjects. This mutation led to the substitution of the physiologic stop codon by an arginine (p.X399R). CONCLUSIONS: Our study highlights the importance of the KISS1R signaling, in gonadotropin-releasing hormone neurons, in the control of reproductive function. Additionally, our data suggests a complex central and peripheral metabolic control of puberty, through the hypothalamic KISS1R signaling. We suggest a mutual link between the hypothalamic-pituitary-gonadal, -adrenal, and -somatotropic axes.
