Charting the future? - researching hereditary quotient in African American families - includes books about medical genealogy

A hundred years ago, infectious diseases, such as cholera and flu, were the major killers in the African-American community. Antibiotics changed all that. Today, the major killers--heart disease, cancer, stroke and liver disease--are "heritable" diseases. They are inherited in two ways.

"In one case you inherit a major gene or several minor genes that cause the disease. You have the disease at birth, or you will get it," explains Dr. Robert F. Murray, the chief of the Division of Medical Genetics in the Department of Pediatrics and Child Health at Howard University College of Medicine in Washington, D.C. "In the other case you inherit the gene that makes you susceptible to the disease. ... [The gene] doesn't predict with certainty that you will get the disease; it just increases the potential."

In the second case, diet, occupation, gender, age, lifestyle habits or ethnic background, alone or in combination, plays a strong, often dominant, role. "If you know your susceptibility and control environmental factors," says Dr. Barbara Quinton, a clinical geneticist and pediatrician at Howard's College of Medicine, "you can do something to guard health."

To do that "something," for yourself and your family, find your family heredity quotient (HQ). Imagine an HQ as a 0 to 100 rating, where a 0 rating means genes contribute nothing to a disease (for example, an infectious disease like mumps) and a 100 rating means the disease--such as sickle cell anemia--is entirely genetically determined. Most diseases fall somewhere in the middle: "That means," says Quinton, "there is a genetic predisposition and an environmental trigger."

To ascertain your HQ, fill in a detailed medical questionnaire (chart, or pedigree). This helps you get organized and look for family patterns, says Dr. Michael Blakey, an associate professor of anthropology at Howard University.

Interview at least three generations. Begin with yourself. Complete the questionnaire, and then get your doctor to give you a detailed rundown on it. Find out what the HQ is for each of your medical problems. Don't ignore emotional, psychological or addiction problems; some researchers believe that they have genetic links.

Next, talk to sisters and brothers about their health status and problems.

Look for patterns. If parents carry a recessive gene for a disease, such as sickle cell anemia, it won't show up in them; it may show up in their children.

Next, interview more distant relatives. Again, look for patterns, but don't confuse family genetic patterns with family social patterns, stresses Blakey: "If you have a long line of kin dying of lung cancer and they all smoke like crazy, maybe it isn't genes. There are patterns of lifestyle behavior that show up in families. ... They, too, are reproduced."

It will take some legwork to track down information on distant relatives and those who are no longer living. For the former, use the mail and make follow-up telephone calls. For the latter, use public records and documents. The best source of information is a death certificate. It will always list the age of death. If the age is under 50, says Quinton, that may be a clue that a high HQ for a disease is at work.

The certificate will also always list the immediate cause of death (for example, stroke), and it may also list the underlying cause (for example, hypertension). It may also list the name of a family physician; he or she may have more medical information. (Use the Genealogist's Address Book, the Vital Records Handbook or the Handy Book for Genealogists for addresses needed for death certificates.)

Other good sources of medical information on nonliving relatives include: newspaper obituaries; insurance company, hospital and medical records (difficult to get since the relatives can't sign a release for them!); elementary school enrollment forms; census records; church and burial records; organization applications; and military records.

Old family photographs are also helpful in identifying genetic abnormalities that run in families. Many diseases, such as severe rheumatoid arthritis or hypercholesterolemia (indicated by an accumulation of fat under the skin around the eyes and across the cheeks that often suggests heart disease) that may not be recorded in written records or remembered by the family historian are recorded in old pictures.

Be thorough. Get ages at which chronic and lateonset diseases, such as arthritis and Huntington's chorea, began. Double-check information whenever possible with another source.

Be tenacious. Ask if there are medical problems not covered on the chart. If you can't get a name for a problem, get its description and symptoms. (Then discuss that information with a doctor.) Ask the hard-to-talk-about questions about miscarriages, stillbirths and early infant deaths. Uncovering an aunt or uncle you never knew about may indicate genetically related medical problems to be on the lookout for when you start a family.

Ask if there is a history of unusual physical characteristics, such as extra fingers or toes (polydactylism) or ear lobes with vertical creases in them. The extra digits mean nothing healthwise. The crease is a benign visible genetic trait--geneticists call it a marker--that correlates to a high degree with predisposition to heart disease, an invisible killer.