Analysis of homeobox gene HOXA10 mutations in cryptorchidism

Purpose: Cryptorchidism is the most common congenital abnormality of the ge nitalia. However, its exact etiology remains to be defined. Homeobox (HOX) containing genes have a key role in the morphogenesis of segmental structur es along the primary body axis, including the urogenital mesenchyma. In mal e mice with a targeted deletion of the HOXA10 gene cryptorchidism manifests in the absence of other major defects. Because to our knowledge this gene has never been examined for alterations in humans, we evaluated whether mut ations of HOXA10 are associated with cryptorchidism in humans. Materials and Methods: Genomic deoxyribonucleic acid (DNA) was extracted fr om human blood or tissue samples from 16 noncryptorchid control subjects an d 45 cryptorchid boys. To screen for mutations exons 1 and 2 of the HOXA10 gene were amplified individually by polymerase chain reaction using 6 overl apping oligonucleotide primer pairs. Single strand conformational polymorph ism (SSCP) analysis of the amplified radiolabeled DNA fragments was perform ed. Variant band shifts were detected due to abnormal migration of the dena tured DNA fragment compared to controls, suggesting an alteration in the DN A sequence. Sequence analysis of these variant bands was then done to defin e any mutations. Results: SSCP analysis revealed variants in 2 controls. Of the 45 samples f rom cryptorchid patients 30 had SSCP variants in exon 1. No variants were f ound in other regions of the gene. Sequence analysis revealed several DNA p olymorphisms in exon 1 in controls and boys with cryptorchidism. Other nucl eotide changes (point mutations) were noted only in exon 1 in the DNA of 5 cryptorchid patients, of whom 1 had a 24 nucleotide deletion. Conclusions: Our initial analysis of the HOXA10 gene in humans demonstrates that genetic alterations of this gene may be present in some boys with cry ptorchidism. HOXA10 polymorphisms exist in normal control subjects as well as in cryptorchid patients. Further analysis of the function of the mutated protein will elucidate the role of this gene as a potential causative fact or of testicular descent.