Broad Phenotypes of Disorders/Differences of Sex Development in MAMLD1 Patients Through Oligogenic Disease.

Christa E Flück,Núria Camats,Isabel Esteva,Luis Castaño,Idoia Martinez De Lapiscina,Kay-Sara Sauter,Mónica Fernández-Cancio,Laura Audí

doi:10.3389/fgene.2019.00746

Abstract

Disorders/differences of sex development (DSD) are the result of a discordance between chromosomal, gonadal, and genital sex. DSD may be due to mutations in any of the genes involved in sex determination and development in general, as well as gonadal and/or genital development specifically. MAMLD1 is one of the recognized DSD genes. However, its role is controversial as some MAMLD1 variants are present in normal individuals, several MAMLD1 mutations have wild-type activity in functional studies, and the Mamld1-knockout male mouse presents with normal genitalia and reproduction. We previously tested nine MAMLD1 variants detected in nine 46,XY DSD patients with broad phenotypes for their functional activity, but none of the mutants, except truncated L210X, had diminished transcriptional activity on known target promoters CYP17A1 and HES3. In addition, protein expression of MAMLD1 variants was similar to wild-type, except for the truncated L210X. We hypothesized that MAMLD1 variants may not be sufficient to explain the phenotype in 46,XY DSD individuals, and that further genetic studies should be performed to search for additional hits explaining the broad phenotypes. We therefore performed whole exome sequencing (WES) in seven of these 46,XY patients with DSD and in one 46,XX patient with ovarian insufficiency, who all carried MAMLD1 variants. WES data were filtered by an algorithm including disease-tailored lists of MAMLD1-related and DSD-related genes. Fifty-five potentially deleterious variants in 41 genes were identified; 16/55 variants were reported in genes in association with hypospadias, 8/55 with cryptorchidism, 5/55 with micropenis, and 13/55 were described in relation with female sex development. Patients carried 1-16 variants in 1-16 genes together with their MAMLD1 variation. Network analysis of the identified genes revealed that 23 genes presented gene/protein interactions with MAMLD1. Thus, our study shows that the broad phenotypes of individual DSD might involve multiple genetic variations contributing towards the complex network of sexual development.

Highlights

Disorders/differences of sex development (DSD) occur when there is a discordance between chromosomal, gonadal, and genital sex (Ostrer, 2014)
The role of MAMLD1 in sex development is controversial for several reasons: a) some MAMLD1 variants are present in the normal population (Fukami et al, 2006; Chen et al, 2010; Gaspari et al, 2011; Kalfa et al, 2011); b) the same MAMLD1 variant may be present in patients with different phenotypes (Camats et al, 2015); c) MAMLD1 variants are not present in all DSD individuals of the same family (Fukami et al, 2006); d) several MAMLD1 mutations present wild-type activity in functional studies (Camats et al, 2015); and e) the Mamld1-knockout male mouse presents with normal genitalia and reproduction (Miyado et al, 2012; Miyado et al, 2017)
Patient 6 carried 16 variants in 16 genes: ATF3, BNC2, CYP1A1, EYA1, FLNA, FRAS1, GLI3, HOXA13, IRX5, IRX6, MAML1, NRP1, MAML3, PROP1, PTPN11 and WDR11 (Table 2). Thirteen of these genes are associated with risk of hypospadias and/or syndromes that include abnormal gonadal/genital development, whereas MAML1 is unrelated, MAML3 has been proposed to be associated with female gonadal development and PROP1 has only been associated with anterior pituitary insufficiency/ hypogonadotropic hypogonadism

Summary

INTRODUCTION

Disorders/differences of sex development (DSD) occur when there is a discordance between chromosomal, gonadal, and genital sex (Ostrer, 2014). We tested functional activity of nine MAMLD1 variants detected in nine 46,XY DSD patients with broad phenotypes (Camats et al, 2015). WES data were filtered by common tools and a disease-tailored algorithm including MAMLD1-related and DSD-related known and candidate genes. WES data were filtered by a disease-tailored list of MAMLD1related and DSD-related known and candidate genes (n = 606) similar to the algorithm previously set up for Camats et al, (2018). F) We run InterVar and VarSome to classify the variants, searched for reported (potentially) human diseasecausing variants with the HGMD, and revised evidences of relationship with DSD, sex development and clinical phenotype of each patient with literature and database search. Synonymous variants were not rejected because it has been shown that they may affect splicing

RESULTS

DISCUSSION

ETHICS STATEMENT