SUN-723 CDH2 Gene Analysis in a Cohort of Patients with Congenital Hypopituitarism

Abstract

Introduction: Hypopituitarism is defined as a deficiency of one or more pituitary hormones. Pathogenic allelic variants in genes implicated in pituitary development were associated in 15% of the patients with congenital hypopituitarism (CH). To improve the molecular diagnosis we performed whole exome sequencing of ten patients born from consanguineous parents with CH. One patient with GH, TSH, ACTH and LH/FSH deficiencies presented an allelic variant c.865G>A, p.V289I in CDH2 gene (exon 7) in homozygous state that was absent in populational databanks. CDH2 produces an N-cadherin protein implicated in cellular adhesion and is responsible for epithelial-mesenchymal transition during pituitary development and differentiation. Aim: To analyze the CDH2 gene in a cohort of unrelated patients with CH. Methods: We selected 143 patients with CH from a single Brazilian center. Genomic DNA, extracted by salting out technique, was submitted to PCR amplification of 15 coding regions, except CG rich exon 1, of the CDH2 gene followed by the Sanger sequencing. Rare allelic variant frequency (MAF<1%) was searched in the populational data bank (ExAC, gnomAD, ABraom). Bioinformatic sites (Human Splicing Finder, Polyphen2, Mutation Taster and Mutation assessor) were used to look for deleterious effects. Results: Three allelic variants were found in this cohort. The allelic variant CDH2 (c.865G>A, p.V289I) was found in heterozygous state in a male patient with short stature diagnosed with GH and TSH deficiencies at the age of 11 that evolved with LH/FSH and ACTH deficiencies. Family segregation showed 3 among 11 normal siblings heterozygous carriers. This variant is rare, in heterozygous state, in populational data bank and it was predicted as deleterious or possibly harmful. The allelic variant c.1202C> A (p.A401D), in exon 9, was found in heterozygous state in a female patient with isolated GH deficiency and intellectual disability. The variant was absent in the databases and predicted as deleterious or disease-causing. The variant was absent in the mother and stepsister and the father was not available for testing. The c.1430_1431delCCinsTG allelic variant (p.P477L) was found in heterozygous state in a patient with septo-optic dysplasia, GH, TSH and ACTH deficiencies. It was absent in the databases and was predicted as deleterious or disease causing. The Human Splicing Finder predicted exonic splicing enhancer breakdown leading to the loss of 93 nucleotides. Normal mother is heterozygous carrier suggesting incomplete penetrance. Conclusion: Heterozygous variants in CDH2 were found in 2% of a cohort of Brazilian patients with congenital hypopituitarism and none in homozygous or compound heterozygous state. Further CDH2 analyses in unrelated patients from different ethnic backgrounds are needed to establish the role CDH2 variants in the etiology of congenital hypopituitarism.