Absence of mutations involving the INSL3 gene in human idiopathic cryptorchidism

The aetiology of cryptorchidism is for the most part unknown and appears to be multifactorial. Recently, a product of Leydig cells termed Leydig insul in-like hormone (INSL3) has been proposed as a putative trophic hormone of the first part of descent. Absence of Insl3 in male mice results in bilater al cryptorchidism and mutations involving this gene may be a cause of crypt orchidism in man. We sequenced both exons of the human INSL3 gene in 31 men who presented with idiopathic unilateral or bilateral cryptorchidism. The only sequence variant was an amino acid substitution in the C-peptide of th e molecule. This change was also found in a control group of normal fertile men indicating that it is a polymorphism unrelated to the phenotype, These results suggest that mutations involving the human INSL3 gene are not a co mmon cause of cryptorchidism in man.