At what age should a child be tested for hemochromatosis if the disorder has been diagnosed in the paternal grandfather? —ARLYN WASCO, MSN, CRNP, Lawrence, Pa.

I assume your question refers to primary hemochromatosis (a form of hereditary hemochromatosis [HH]), which is an autosomal recessive disorder. HH is one of the most common genetic disorders, occurring in one in every 200-400 Caucasians. Approximately 12% of Caucasians carry the gene. In this case, the paternal grandfather has HH and his son, the father of the child in question, may be a carrier or have HH but is not displaying symptoms yet. The child would have to inherit the gene from his mother as well to have a 25% chance of having the disease. There is no special age for genetic testing, but as with all genetic tests, counseling is recommended before the testing and when the results are provided so that the patient and family fully understand the implications for prevention, treatment, and family planning.—Julee B. Waldrop, MS, PNP (131-12)