Baylor College of Medicine scientists defined a previously unrecognized genetic cause for two types of birth defects found in newborn boys, described in a report published in the journal Nature Medicine.
Cryptorchidism is characterized by the failure of descent of one or both testes into the scrotum during fetal development. In the adult man, the testes produce sperm and the male hormone, testosterone. Hypospadias is the abnormal placement of the opening of the urethra on the penis. Both birth defects are usually surgically repaired during infancy.
Lamb and colleagues used a method of genome wide screening (essentially a molecular karyotype) called array comparative genomic hybridization to study children with these defects. The method looks specifically at changes in chromosomal regions that have undergone duplication or deletions too small to see under a microscope, termed copy number variations. These genomic changes can alter gene dosage (gene gains or losses) resulting in a change in cell function.
“The birth defects were a result of microduplication on the X chromosome that altered estrogen receptor and androgen receptor action in ways not previously recognized,” said Lamb.
Read the full, original story: New genetic cause of male reproductive birth defects identified