Screening of MAMLD1 Mutations in 70 Children with 46,XY DSD: Identification and Functional Analysis of Two New Mutations

Nicolas Kalfa,Charles Sultan,Maki Fukami,Francoise Audran,Michel Polak,Catherine Pienkowski,Totsumo Ogata,Jacques Weill,Graziella Pinto,Pascal Philibert,Sylvie Manouvrier,Irina Agoulnik

doi:10.1371/journal.pone.0032505

Abstract

More than 50% of children with severe 46,XY disorders of sex development (DSD) do not have a definitive etiological diagnosis. Besides gonadal dysgenesis, defects in androgen biosynthesis, and abnormalities in androgen sensitivity, the Mastermind-like domain containing 1 (MAMLD1) gene, which was identified as critical for the development of male genitalia, may be implicated. The present study investigated whether MAMLD1 is implicated in cases of severe 46,XY DSD and whether routine sequencing of MAMLD1 should be performed in these patients.Seventy children with severe non-syndromic 46,XY DSD of unknown etiology were studied. One hundred and fifty healthy individuals were included as controls. Direct sequencing of the MAMLD1, AR, SRD5A2 and NR5A1 genes was performed. The transactivation function of the variant MAMLD1 proteins was quantified by the luciferase method.Two new mutations were identified: p.S143X (c.428C>A) in a patient with scrotal hypospadias with microphallus and p.P384L (c.1151C>T) in a patient with penile hypospadias with microphallus. The in vitro functional study confirmed no residual transactivating function of the p.S143X mutant and a significantly reduced transactivation function of the p.P384L protein (p = 0.0032). The p.P359S, p.N662S and p.H347Q variants are also reported with particularly high frequency of the p.359T- p.662G haplotype in the DSD patients.Severe undervirilization in XY newborns can reveal mutations of MAMLD1. MAMLD1 should be routinely sequenced in these patients with otherwise normal AR, SRD5A2 and NR5A1genes.

Highlights

The disorders of sex development (DSD) comprise a variety of anomalies defined by congenital conditions in which chromosomal, gonadal, or anatomical sex is atypical
Mutations of Mastermind-like domain containing 1 (MAMLD1) and functional analyses Among the 70 newborns and children with 46,XY DSD, two new mutations were identified in two unrelated patients: p.S143X (c.428C.A) and p.P384L (c.1151C.T) (Fig. 1)
MAMLD1 is a good candidate to explore in patients with unexplained 46,XY DSD, as it has been shown to be expressed in fetal Leydig cells around the critical period for sex development [15]

Summary

Introduction

The disorders of sex development (DSD) comprise a variety of anomalies defined by congenital conditions in which chromosomal, gonadal, or anatomical sex is atypical. The prevalence of the 46,XY disorders of sex development (46,XY DSD) is difficult to determine with accuracy because of the heterogeneity in the clinical presentation and the etiologies. Two independent surveillance systems in the United States, the nationwide Birth Defects Monitoring Program (BDMP) and the Metropolitan Atlanta Congenital Defects Program (MACDP), reported a near doubling in the hypospadias rate in comparison with the immediately preceding decades [3]. The etiologies of 46,XY DSD are usually gonadal dysgenesis (defect in SRY and downstream genes such as SOX9, WT1, NR5A1 [6,7], etc.), defects in androgen biosynthesis and, more frequently, abnormalities in androgen sensitivity. An AR gene defect is identified in less than 10% of the cases [9]

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