However, homozygous variants in HSD17B4 (D-bifunctional protein deficiency (MIM# 261515), Perrault syndrome 1 (MIM# 233400)) and ACOX2 (Bile acid synthesis defect, congenital (MIM# 617308)) have reliably been associated with monogenic diseases. This evidence concerns the gene HSD17B4 and hereditary thrombophilia due to congenital protein S deficiency.