8696 Whole Exome Sequence Analysis in a Naïve Cohort of Congenital Hypopituitarism in a Single Center

Abstract Disclosure: F.Q. Aratani: None. D.P. Di Matteo: None. I.P. de Magalhães: None. P. Frudit: None. L.S. Motomia: None. S.K. Beeby: None. L.R. Barros: None. D.D. Bissegatto: None. L.R. Carvalho: None. Background: Deficiency of one or more pituitary hormones is defined as hypopituitarism. In the literature, molecular diagnosis (MD) is defined in 12% by the Sanger sequencing and large scale sequencing increased this number to 15%. Aim: To perform whole exome sequencing (WES) in a cohort of patients with congenital hypopituitarism (CH) naïve to MD approach. Patients: Nine patients with CH followed in a single Brazilian tertiary center were included. Methods: Libraries were prepared with kits from Agilent and sequenced on Hi-Seq (Illumina). The variants were called following GATK best practices, using the Haplotypecaller and genome version hg38. They were classified in the Franklin by genoox (https://franklin.genoox.com/clinical-db/home). WES that did not pass the platform's initial quality control and variants that did not reach an adequate confidence level (low/medium confidence: VAF < 50%) were excluded. The remaining variants were classified according to ACMG criteria. Results: Three among 9 patients presented allelic variants and aredescribed here. Case 1: A 22-year-old female presented height of 143 cm (-3,13 SDS) at the first visit without signs of puberty, had delayed bone age (DBA), hypoplastic adenohypophysis, interrupted pituitary stalk (IPS) and ectopic neurohypophysis (ENH) at the magnetic resonance imaging (MRI). Hormonal profile showed low E2, GH, FSH and LH. Twoheterozygous missense variants in the ALMS1 gene (c.5450G>A : p.Arg1817GIn; and ALMS1:c.4225G>C: p.Ala1409Pro) were seen in the exome; both classified as VUS according to ACMG criteria. This allelic variant is related to Alstrom Syndrome. Case 2: A 7-year-old female presented with short stature and was diagnosed with GH followed by LH/FSH, TSH and ACTH deficiencies. At MRI presented IPS and ENH. A heterozygous variant in the PROK2 gene c.364C>T p.R122 with a premature stop codon and truncated protein was present and classified as probably pathogenic according to ACMG criteria. This variant was already described with hypogonadotropic hypogonadism (HH) with or without anosmia. Case3: A 15-year-old male was referred with growth hormone deficiency (GHD), DBA, and HH. Growth hormone replacement was started followed by testosterone. Despite delayed puberty, the testes were normal in size. WES showed a variant c.629G>A:p.Trp210*, in hemizygosity in IGSF1 gene and was classified as probably pathogenic according to ACMG criteria. Loss-of-function mutations in IGSF1 may cause an X-linked syndrome of central hypothyroidism, macroorchidism and delayed puberty (delayed rise of testosterone, but normal timing of testicular growth). Conclusion: WES in a cohort of patients with congenital hypopituitarism naïve to molecular diagnosis revealed 33% (3/9) with positive genetic findings, two of them with clinical significance and family segregation according to the genetic inheritance. Presentation: 6/3/2024