Alports Syndrome

I am new to this site. My husband was the eldest of six. Three boys and three girls. Two boys and one girl were dx in their teens, all with hearing loss and vision problems. First boy died at 16 in 1969 hence the diagnosis. Second boy died at age 42 after dialysis, transplant after 20 yrs. Transplanted kidney failed, dialysis until death. Girl 42 on dialysis after giving birth 16 years ago.
We have two children ages 31 and 20. No signs of the disease. Two grandchildren ages 3 and 2. Both fine so far.
My husband's family has no other members with the disease. He comes from a very large family. Mother was 1 of 11 children. Father 1 of 6.
He has over 40 first cousins and over one hundred living first, second and third cousins. No other dx of the disease anywhere in the living family. Past generations on both sides all lived to old age.
I guess my question is where did this disease come from? Our family doesn't seem to follow the usual heredity theory?
Anyone with any ideas?

Leah