HORMAD1 and Azoospermia: Of the 17 genes, horma domain-containing 1 (HORMAD1) gene is located on chromosome 1q21.3, and its expression in testis coincided with the onset of meiosis I;[19] Ornithine decarboxylase antizyme 3 (OAZ3) gene, mapped on chromosome 1 at 1q21.3, began to express in the early stage of spermatogenesis and ended in the late spermatid phase.[20] The relationship between these genes and azoospermia needs further study.