Insufficient info. I suspect you mean IgA nephropathy. Iga (immunoglobulin a) is one of the 5 groups of proteins that contain antibodies. Iga nephropathy is an autoimmune kidney disease where IgA can be found in the kidney. The disease responds poorly to treatment. Your cousin should see a kidney specialist who has an interest in this disease in a tertiary care center.
Search the internet. Autoimmune disorders are the specialty of "rheumatologists". Immune system disorders and some autoimmune disorders are the specialty of "immunologists", who usually are also allergists. If one cannot find these specialists locally, the nearest university medical center should have them. Rare diseases may have special research centers somewhere in the country. An internet search can locate them.