Other candidate genes near the ABO locus include genes for the pregnancy-associated plasma protein (PAPPA), microcephaly, thrombotic thrombocytopenic purpura, acute hepatic porphyria and susceptibility to lead poisoning, amyloidosis, juvenile amyotrophic lateral sclerosis, hypophosphatemic rickets, COX deficiency, tuberous sclerosis, lymphangioleiomyomatosis, muscular dystrophy, Ehlers-Danlos connective tissue disease, aortic valve disease, susceptibility to colorectal cancer, and longevity [47]. The gene discussed is PAPPA; the disease is thrombotic thrombocytopenic purpura.