Usher syndrome - prevalent with the Acadian French

Usher syndrome is a condition that affects both hearing and vision. The major symptoms of Usher syndrome are deafness or hearing loss and an eye disease called retinitis pigmentosa.

About 1 in 75 people carries the Usher gene, but most don’t realize they have it. Usher syndrome is an autosomal-recessive disorder, meaning that for a child to have the condition, both parents must be carriers of the gene. And with each such pregnancy, there is a 1-in-4 chance of the child having Usher syndrome. Thus, the chance of having a child with Usher syndrome is relatively rare even among those who carry the gene, and that is why the prevalence of Usher syndrome is so low.

However, the odds of producing an offspring with Usher syndrome rise dramatically among people who are related. Unfortunately, social forces have operated historically to make the likelihood of intermarriage higher among a certain cultural group: the Acadian French of south Louisiana. This has resulted in a relatively higher number of people with Usher syndrome in this area of the country.

The high prevalence of Usher syndrome in south Louisiana is also the subject of a video narrated by the well-known neurologist Oliver Sacks, The Ragin’ Cajun Usher Syndrome.

TLDR version: You coonasses need to stop marrying your cousins!