<i>MAMLD1</i> (alias <i>CXorf6</i>) was first documented in 2006 as a causative gene of 46,XY differences/disorders of sex development (DSD). <i>MAMLD1</i>/<i>Mamld1</i> is expressed in the fetal testis and is predicted to enhance the expression of several Leydig cell-specific genes. To date, hemizygous <i>MAMLD1</i> variants have been identified in multiple 46,XY individuals with hypomasculinized external genitalia. Pathogenic <i>MAMLD1</i> variants are likely to cause genital abnormalities at birth and are possibly associated with age-dependent deterioration of testicular function. In addition, some <i>MAMLD1</i> variants have been identified in 46,XX individuals with ovarian dysfunction. However, recent studies have raised the possibility that <i>MAMLD1</i> variants cause 46,XY DSD and ovarian dysfunction as oligogenic disorders. Unsolved issues regarding MAMLD1 include the association between <i>MAMLD1</i> variants and 46,XX testicular DSD, gene-gene interactions in the development of <i>MAMLD1</i>-mediated DSD, and intracellular functions of MAMLD1.
Sertoli Cell Wt1 Regulates Peritubular Myoid Cell and Fetal Leydig Cell Differentiation during Fetal Testis Development