SUN-246 Low Frequency of Pathogenic Allelic Variants in the Disorders of Sex Development Related Genes in Small for Gestational Age Children with Hypospadias

Abstract

Background: Small for gestational age (SGA) children are defined as the one with birth weight and/or length 2 or more standard deviations below the population mean for gestational age. The underlying causes of pre and postnatal growth failure are diverse1. SGA boys present a high frequency of hypospadias (15 to 30%) of unknown etiology2. Objective: To analyze the prevalence of SGA individuals with hypospadias in a large cohort of 46, XY disorders of sex development (DSD) patients (n=272) followed in a tertiary center and to search for a molecular etiology associated with this phenotype. Patients and methods: We evaluated 30 SGA children with medium or proximal hypospadias, four of them presented syndromic characteristics associated. DNA samples of 24 patients were studied by target massively parallel sequencing (TPMS) using an amplicon-based capture panel of 63 genes related to DSD, and one by whole exome sequencing (WES). TPMS and WES were performed in the Illumina MiSEQ/HiSEQ platforms, respectively. Paired-end reads were aligned to the hg19 assembly of the human genome with BWA-MEM. Variants were called and annotated with Platypus and ANNOVAR. Results: The prevalence of SGA individuals with hypospadias in the 46, XY DSD cohort was 11%. Two children had clinical features of Silver-Russell syndrome and their diagnosis was confirmed (11p15 LOM) by MLPA. The two other syndromic patients were suspected with three M syndrome and Mulibrey Nanism. The TPMS study identified three likely pathogenic variants in these patients: p.Trp1538* and p.Gln813fs variants in compound heterozygosis in CUL7 gene and the homozygous p.Gly340fs variant in TRIM37. Seven heterozygous variants with uncertain significance in 5 DSD related genes were identified: two in the DHX37, p.V717I and p.A737T, associated with GATA4 p.P407R variant and with WWOX p.Y85D, respectively; the WT1 p.C350R variant, the IGF1R p.R1337C variant, and the BMP8B p. Arg116Cys variant. The frequency of likely pathogenic variants in SGA children with hypospadias was 10%. Conclusion: The low frequency of pathogenic allelic variants identified in SGA children with hypospadias indicates that other mechanisms, as epigenetic changes, may be involved in the etiology of this condition. 1 CLAYTON, P. E. et al. Management of the Child Born Small for Gestational Age through to Adulthood: A Consensus Statement of the International Societies of Pediatric Endocrinology and the Growth Hormone Research Society. The Journal Of Clinical Endocrinology & Metabolism, [s.l.], v. 92, n. 3, p.804-810, mar. 2007. The Endocrine Society. http://dx.doi.org/10.1210/jc.2006-2017. 2 MOREL, Y et al. Aetiological diagnosis of male sex ambiguity: a collaborative study. European Journal Pediatric, [s. L.], v. 161, n. 1, p.49-59, jan. 2002.