Genetic diagnosis of congenital hypopituitarism by Molecular Inversion Probes Sequencing: Novel pathogenic variants

VISHNOPOLSKA, SEBASTIAN; BERGADA, IGNACIO; PÉREZ GARRIDO, NATALIA; BELGOROSKY, ALICIA; CAMPER, SALLY; CAMILLETTI, MARIA ANDREA; BRASLAVSKY, DÉBORA; MARINO, ROXANA; CIACCIO, MARTA; MARTI, MARCELO; PEREZ-MILLÁN, MARIA INES; MERCOGLIANO, MARIA FLORENCIA; KESELMAN, ANA; RAMIREZ, PABLO; DI PALMA, MARIA ISABEL; KITZMAN, JACOB

Mar del Plata

Congreso; Reunion Anual de Sociedades de Biociencias; 2019

Congenital hypopituitarism (CH) is a life-long and threatening disease, associated with an abnormal pituitary development. CH is highly variable comprising a spectrum of disorders that range from isolated growth hormone deficiency (IGHD) to combined pituitary hormone deficiency (CPHD). Mutations in at least 30 genes have been implicated in CH, but atpresent, precise diagnosis remains a challenge. In the present study, we report variants found in pediatric patients with CPHD (n=116) or IGHD (n=55) from Argentina using the molecular inversion probes sequencing (MIPS) method and our own custom designed gene panel. We identified pathogenic, likely pathogenic or variants with uncertain significance but predicated to be damaging for at least 3 independent software in about 23% of the cases. We have identified a number of phenotypes associated with mutations in known genes that cause hypopituitarism (HESX1, LHX3, LHX4, GLI2); in less frequently reported genes (BMP4, FGFR1, GLI3, TGIF1, FOXA2) and in genes that require additional evidence about causality (ARNT2, ZSWIM6, GPR161, PNPLA6, CDH2). We have identified de novo heterozygous variants in LHX3 and LHX4, transcription factors involvedin the development of the pituitary. Two variants on LHX3 (p.L220S and p.P187S) were found in a patient with IGHD and a patient with CPHD, micrognathia, chiasm hypoplasia and bilateral cryptorchidism. LHX4 variants (p.Q100H, p.W204L and p.R84H) were found in a child with septo optic dysplasia, a child with CPHD and a third patient with GH andTSH deficiency, respectively. Transient transfection of HEK293T cells with human wild-type or mutant hLHX3/ hLHX4 showed an impairment in transcriptional reporter activity by the mutant variants, except for variant LHX4 p.R84H. Collectively, using the first screening panel for known genes and candidate genes for CH, we identified a significant number of variants in a large cohort of patients associated with the complex phenotype. Our studies will facilitate early diagnosis and prognosis, assessing the risk of future affected individuals.Furthermore, understanding the mechanisms behind new genes involved in CH would lead us to develop new tailor-made therapies that could benefit the patients.