Prevalence of endocrine and genetic abnormalities in boys evaluated systematically for a disorder of sex development

Abstract

STUDY QUESTION What is the likelihood of identifying genetic or endocrine abnormalities in a group of boys with 46, XY who present to a specialist clinic with a suspected disorder of sex development (DSD)? SUMMARY ANSWER An endocrine abnormality of the gonadal axis may be present in a quarter of cases and copy number variants (CNVs) or single gene variants may be present in about half of the cases. WHAT IS KNOWN ALREADY Evaluation of 46, XY DSD requires a combination of endocrine and genetic tests but the prevalence of these abnormalities in a sufficiently large group of boys presenting to one specialist multidisciplinary service is unclear. STUDY, DESIGN, SIZE, DURATION This study was a retrospective review of investigations performed on 122 boys. PARTICIPANTS/MATERIALS, SETTING, METHODS All boys who attended the Glasgow DSD clinic, between 2010 and 2015 were included in the study. The median external masculinization score (EMS) of this group was 9 (range 1-11). Details of phenotype, endocrine and genetic investigations were obtained from case records. MAIN RESULTS AND THE ROLE OF CHANCE An endocrine abnormality of gonadal function was present in 28 (23%) with a median EMS of 8.3 (1-10.5) whilst the median EMS of boys with normal endocrine investigations was 9 (1.5-11) (P = 0.03). Endocrine abnormalities included a disorder of gonadal development in 19 (16%), LH deficiency in 5 (4%) and a disorder of androgen synthesis in 4 (3%) boys. Of 43 cases who had array-comparative genomic hybridization (array-CGH), CNVs were reported in 13 (30%) with a median EMS of 8.5 (1.5-11). Candidate gene analysis using a limited seven-gene panel in 64 boys identified variants in 9 (14%) with a median EMS of 8 (1-9). Of the 21 boys with a genetic abnormality, 11 (52%) had normal endocrine investigations. LIMITATIONS, REASONS FOR CAUTION A selection bias for performing array-CGH in cases with multiple congenital malformations may have led to a high yield of CNVs. It is also possible that the yield of single gene variants may have been higher than reported if the investigators had used a more extended gene panel. WIDER IMPLICATIONS OF THE FINDINGS The lack of a clear association between the extent of under-masculinization and presence of endocrine and genetic abnormalities suggests a role for parallel endocrine and genetic investigations in cases of suspected XY DSD.