SUN-074 Loss-Of-Function Mutations in GATA4 in Patients with 46,XY Disorders of Sex Development Without Cardiac Defects

Background: Disorders of sex development (DSD) encompass a wide range of conditions associated with numerous causative genes. In about 50-60% of 46,XY DSD individuals, the underlying molecular cause remains uncertain. GATA4 haploinsufficiency has been described in patients with congenital heart defects (CHD), while only a few studies reported mutations related to 46,XY DSD phenotype. This study investigated clinical phenotypes and molecular characteristics of two 46,XY DSD patients with GATA4 mutations. Methods: Mutation analysis was performed in patients with 46,XY DSD by whole exome sequencing (WES) using Illumina NextSeq platform. Clinical and endocrine characteristics were reviewed retrospectively. GATA4 variants identified by WES were verified by Sanger sequencing. Functional activity of GATA4 variants was tested by luciferase reporter assay on the SRY and AMH promoter using two different cell systems including HEK293 and NCI-H295R. Results: Subject 1 presented with micropenis and hypospadias at the age of 5 months. Karyotype was 46,XY. Mullerian duct remnants were not found in pelvic ultrasound. The patient underwent urethroplasty at the age of 10 months and was reared as a male. Subject 2 with complete female external genitalia was referred to our hospital because of 46,XY karyotype on G-scanning. The patient underwent laparoscopic orchiectomy at the age of 1.8 years and was assigned as a female. Both patients were responsive to hCG stimulation tests and did not have CHD. Subject 1 harbored a novel heterozygous variant of c.643A>G (p.R215G)] in GATA4, whereas a previously reported variant of c.1220C>A (p.P407Q) was identified in Subject 2. In vitro luciferase reporter assays using SRY and AMH promoter revealed decreased transcriptional activity of both p.P407Q and p.R215G. Conclusions: This study expanded phenotypic spectrum of mutations in GATA4 in patients with 46,XY DSD without CHD. GATA4 mutations in patients with 46,XY DSD may not be associated with CHD. Possible explanations for phenotypical variability comprise incomplete penetrance, variable expressivity, and oligogenic mechanisms.