Autosomal Recessive Carrier?

My husband's sister and her husband have 3 sons with the Autosomal Recessive RP, and a daughter who is a carrier; so both my husband's sister and her husband each have one Recessive RP autosome, but they don't have RP themselves.  They did not know that they each had a Recessive RP autosome, as no one in their respective families has RP, until their eldest son started to develop symptoms, and he was examined.

My husband's mother does not have RP and was examined and found not to be a carrier, so it's assumed that my husband's sister inherited her defective Recessive autosome from my husband's father, who could not be examined, because he passed away before the grandchildren were born; but he did not have RP.

So genetically, my husband's sister must have inherited her defective Recessive autosome from my husband's father, together with the X sex chromosome.  My husband inherited the Y sex chromosome from his father.

Does this mean that the defective Recessive autosome was passed from the father, only to my husband's sister, together with the X sex chromosome;

or could the defective Recessive autosome have been passed from the father, also to my husband, together with the Y sex chromosome, thereby possibly making him a possible Autosomal Recessive RP carrier?  He does not have RP.

I am concerned, because we have a child.

Thank you.

[John C Hagan III, MD, FACS, FAAO]

The inheritance of retinitis pigmentosa (RP) is very difficult to understand because it is transmitted in different ways in different individuals (autosomal domininant and recessive, sex-linked, spontaneous mutation in somatic cells, spontaneous mutation in germinal cells, and widely variable penetrance).

I would suggest you see a retina specialist to examine your child, with a physicial exam and electrophysiologic tests it should be possible to determine if you child has normal retina function or harbors an abnormality.

Actually the suppositions you make in the first part of your questions could best be done by seeing a medical geneticist and working out pedegrees for the last several generation.

JCH III MD Eye Physician and Surgeon