A prosthesis is a functional replacement for an amputated or congenitally malformed or missing limb. Intersex people were historically termed hermaphrodites, "congenital eunuchs", or even congenitally "frigid". Superior mesenteric artery syndrome is a rare abnormality caused by a congenitally short suspensory muscle. Humans are gradually losing their third molars, with some individuals having them congenitally absent. GnRH formation is congenitally absent in Kallmann syndrome. Of those afflicted with sensorineural hearing loss, approximately 50% are congenitally related. Bailey discusses whether homosexuality is a congenitally or possibly even genetically related phenomenon. Patients with such mutations are congenitally insensitive to pain and lack other neuropathies. It is abnormal in spondylolysis, either due to fracture or congenitally. The result is a normally functioning esophagus, virtually indistinguishable from one congenitally well formed. Patients with bradycardia have likely acquired it, as opposed to having it congenitally. According to Kakulas and Adams, pectoralis major is the most frequently congenitally absent muscle. The problem of premature and congenitally ill infants is not a new one. The subitizing effect has also been obtained in tactile perception with congenitally blind adults. NICUs now concentrate on treating very small, premature, or congenitally ill babies.