Wednesday, October 22, 2014
Inherited Disorders and Birth Defects
My sister was diagnosed with Ullrich’s Disease by skin biopsy. My mother tested positive as a carrier and my father’s results are not back yet. I have two non-affected daughters and wondered if their children are at risk for the disease?
Ullrich congenital muscular dystrophy is caused by changes (mutations) in one of 3 genes that code for a type of collagen (type VI). Collagen is a protein that is involved in muscle development. Children with Ullrich CMD have muscle weakness and poor muscle tone (hypotonia) at or near birth. They can have contractures (stiff joints) in some of their joints such as the hips and elbows and may be very lax (loose joints) in their fingers and toes. The disease is usually progressive.
Ullrich CMD is inherited as an autosomal recessive disease - that is, both parents are carriers for the gene and have a 25% chance of both passing the mutated gene on at the same time and having an affected child.
In order for you to have a child with Ullrich CMD, both you and your husband must be carriers for one of the genes that cause Ullrich CMD. Because you know that your parents are carriers since your sister has the disease, you have a 2/3rd chance to be a carrier as we know you are not affected. If your husband does not have any affected relatives - his chance to be a carrier is the general population risk for this disease. This type of muscular dystrophy is very rare - so his chance of being a carrier is very low.
You could consider having genetic testing and look for the gene that caused the disease in your sister. If you do not have it - then your daughters would not be carriers and thus, could not pass the abnormal gene on to any of your grandchildren. If you are a carrier, then you could have passed on the mutated gene and one or both of your daughters could be carriers. Unless they were to marry a relative, the chance that their husbands would be carriers is like you - very small.
I would recommend that you talk to a genetic counselor to discuss this in detail. The geneticist or genetic counselor would also be able to assist you with genetic testing if you decide you want to have testing. You can locate a genetics center near you through the National Society of Genetic Counselors Resource center at the web site listed below.
Anne Matthews, RN, PhD
Associate Professor of Genetics
School of Medicine
Case Western Reserve University