Can Tangier disease cause male infertility? A case report and an overview on genetic causes of male infertility and hormonal axis involved

Tangier disease is an autosomal recessive disorder caused by mutations in the ABCA1 gene and characterized by the accumulation of cholesteryl ester in various tissues and a near absence of high-density lipoprotein. The subject in this investigation was a 36-year-old Italian man with Tangier disease. He and his wife had come to the In Vitro Fertilization Unit, Pesaro Hospital (Azienda Ospedaliera Ospedali Riuniti Marche Nord) seeking help regarding fertility issues. The man was diagnosed with severe oligoasthenoteratozoospermia. Testosterone is the sex hormone necessary for spermatogenesis and cholesterol is its precursor; hence, we hypothesized that the characteristic cholesterol deficiency in Tangier disease patients could compromise their fertility. The aim of the study was to therefore to determine if there is an association between Tangier disease and male infertility. After excluding viral, infectious, genetic and anatomical causes of the subject's oligoasthenoteratozoospermia, we performed a hormonal analysis to verify our hypothesis. The patient was found to be negative for frequent bacteria and viruses. The subject showed a normal male karyotype and tested negative for Yq microdeletions and Cystic Fibrosis Transmembrane Conductance Regulator gene mutations. A complete urological examination was performed, and primary hypogonadism was also excluded. Conversely, hormonal analyses showed that the subject had a high level of follicle stimulating hormone and luteinizing hormone, low total testosterone and a significant decline in inhibin B. We believe that the abnormally low cholesterol levels typically found in subjects with Tangier disease may result in a reduced testosterone production which in turn could affect the hormonal axis responsible for spermatogenesis leading to a defective maturation of spermatozoa.