5.2 GENETIC DEFECTS
It has often been said that "nobody's perfect," and this is certainly true in regard to the form and function of our bodies. We al! carry through life at least some inherited weaknesses and deficiencies which prevent us from enjoying complete physical and mental vigor from birth to old age. Most often these deficiencies are relatively inconsequential, such as premature baldness or flat feet. However, in certain cases they may be very serious, such as hemophilia, sickle-cell anemia, or some forms of muscular dystrophy. There is no doubt that much human suffering could be prevented if these and similar genetic defects would cease to be transmitted from one generation to the next.
Unfortunately, some genetic defects can be transmitted by hidden carriers, i.e., men and women who themselves remain unaffected and therefore often unaware of the possible danger to their offspring. The reason for this can be found in the laws of heredity.
Generally speaking, genetic defects come in two varieties: dominant and recessive. A dominant genetic defect can be transmitted through one parent alone. In other words, even if only one of the parents has a dominant genetic defect they will transmit it to half of their children. A recessive genetic defect can be transmitted only by both parents. In other words, if only one of the parents has a recessive genetic defect they will not transmit it to any of their children. However, if both parents have the same recessive genetic defect they will transmit it in the following way: On the average, for every four children, one child will be completely unaffected, two children will be hidden carriers, and one child will show the defect.
In view of these facts, some people may find it useful to seek genetic counseling before they decide to have children. A careful examination of a couple and their family medical histories can provide valuable clues as to their chance of transmitting serious genetic defects. Most couples will find that they have little to worry about. However, a few may learn just in time that they cannot have a healthy baby of their own, and that they can find greater happiness through adoption. There are also some rare cases where severe genetic defects or other serious abnormalities of an unborn baby are discovered in the course of a woman's pregnancy. Even in the more restrictive past, such a discovery has usually been considered sufficient reason for a legal abortion.
In the United States there are now several hundred laboratories offering various genetic services. More than 200 of these offer genetic counseling. Further information is available from: The National Genetics Foundation, 250 West 57th St., New York, N.Y. 10019; The National Foundation-March of Dimes, P.O. Box 2000, White Plains, N.Y. 10602; and the Information Office, National Institute of General Medical Services, National Institute of Health, Bethesda, Md. 20014.