Heterotaxy, visceral, 9, autosomal, with male infertility

Visceral heterotaxy-9 (HTX9) is an autosomal recessive disorder characterized by randomization of organ laterality, resulting in defects such as situs inversus and dextrocardia. Affected males are infertile mainly due to defective sperm motility, whereas affected females do not appear to have fertility problems. The disorder results from impaired function of the embryonic nodal cilia and sperm flagella. However, patients do not have classic respiratory symptoms of primary ciliary dyskinesia (see, e.g., CILD; 244400). The phenotype is highly variable; some affected individuals may be identified incidentally (summary by Ta-Shma et al., 2018 and Leslie et al., 2020). For a discussion of the genetic heterogeneity of visceral heterotaxy, see HTX1 (306955). [from OMIM]