My 13 year old daughter was diagnosed with Type 1 diabetes 2 weeks ago. We also have a 11 year old daughter who has Down’s syndrome and hypothyroidism. I am aware of the connection of Down’s syndrome and diabetes.

I am wondering if my 11 year old has a greater risk because her sister has developed diabetes? Also, is it true that the gene for diabetes may be on the 21st chromosome?

Your 11 year old daughter has an approximately tenfold increased chance of getting Type 1A (autoimmune) diabetes before age 20 as compared to a child of the same age who has no affected sibling. This probability is further increased by the hypothyroidism which suggests that she may already have the Autoimmune Polyglandular Syndrome, a condition in which one or more autoimmune syndromes, including diabetes, may be associated. There is no single gene for diabetes; but in Type1A the main predisposing genes are for the MHC (Major Histocompatibility Complexes) which are in the short arm of chromosome 6.

At all events I think you should talk to your younger daughter’s doctor about getting an antibody testing since a negative result would indicate that she is unlikely to follow her sister’s course. A number to call for more information is 1-800-425-8361.

DOB