AP4B1 and rheumatoid arthritis: Among them, three genes were human genetic disease-associated: AP4B1, associated with autosomal recessive spastic paraplegia 47 (MIM # 614,066), LRIG2, associated with autosomal recessive urofacial syndrome 2 (MIM # 615,112), and PTPN22, associated with susceptibility to diabetes type 1 (MIM # 222,100), rheumatoid arthritis (MIM # 180,300), and systemic lupus erythematosus (MIM # 152,700).