How Does Heredity Effect Your Unborn Baby?

Ask any couple what proportion of their genes their children will inherit from each of them and you will uniformly hear "half." Besides the obvious inheritance, common features, your genes also carry genetic information and disorders. Incredibly, few couples take the time to carefully assess and determine their own genetic makeup, and in particular, their own medical family history. Time and again, I have encountered couples who, after having a child with a serious birth defect or mental retardation, later discovered clues in their family histories that would have provided ample warning that testing was necessary.

Building Your Family Tree

Among the most important steps a couple can take to have the healthiest baby possible is to become fully informed about their respective family histories. A fun and informative way to do this is to build a family tree. Before getting started, there are a couple key items you'll need to keep in mind:

1. Try to plan your pregnancy. This can, of course, be easier said than done. But if you are able to plan your conception, you'll be able to first gather a wealth of information about your family history before baby arrives.
2. Stay in touch with a family member who corresponds with or knows where to find key relatives. Strive to acquire medical information about your parents, grandparents, brothers and sisters, aunts and uncles, and first cousins.
3. Draw a family tree as shown in the illustration below and try to update it annually. Note how the family origins are indicated (e.g., Italian) and notes are entered below each symbol.

Determining Health Issues

From this type of family tree, a clinical geneticist might be concerned the female in generation II-2 who had early cataracts and whose son (III-4) may have had one type of muscular dystrophy. This concern would be heightened by the unexplained sudden death (IV-5) who may have inherited the same gene that caused the cataracts and the muscular dystrophy and affected his heart. Individuals IV-3, IV-4 and IV-6 may all be at risk and benefit from genetic counseling and possibly DNA analysis. The occurrence of deafness at birth in IV-6 strongly suggests a particular recessive form of congenital deafness from a gene mutation shared by the first cousin parents. DNA carrier tests for non-syndromic deafness for IV-6 would be recommended, and if positive, carrier tests for IV-3 and IV-4. Pregnancies by IV-3, IV-4 and IV-6 would all be monitored by high-resolution ultrasound at least, given the history of Spina Bifida.