Nail–patella syndrome 5% of NPS patients. Hypothyroidism, irritable bowel syndrome, attention deficit hyperactivity disorder (ADHD), and thin tooth enamel are associated with NPS, but whether these are related or simply coincidences are unclear. The Nail–patella syndrome is inherited via autosomal dominancy linked to aberrancy on human chromosome 9's q arm (the longer arm), 9q34. This autosomal dominancy means that only a single copy, instead of both, is sufficient for the disorder to be expressed in the offspring, meaning the chance of getting the disorder from an affected heterozygous parent is 50%. The frequency of the occurrence is 1/50,000. The disorder is linked
Traditional Chinese medicines derived from the human body "Three Corpses; demonic spirits believed to live in the human body and hasten death" and "gǔdú" 蠱毒 "gu poisoning"; a poison produced by venomous insects; cast a black magic spirit possession over someone". The first "Bencao gangmu" prescription for human nails is not from Chinese medical texts but from Daoist rituals for expelling what (Cooper & Sivin (1973: 220) describe as the "Three Corpse-Worms 三尸, the chief of the "inner gods" who are to the individual microcosm what the celestial bureaucracy is to the cosmos." Prescription 52.6.1, the 斬三尸法 "Method of Beheading the Three Corpses", involves supernaturally cutting the nails