Differences in the Frequency of Various Genetic Diseases

The Rh System

Hemolytic Disease of the Newborn Caused by Rh Incompatibility

In pregnant Rh-negative women, the risk for immunization by Rh-positive fetal red blood cells can be minimized with an injection of Rh immune globulin at 28 to 32 weeks of gestation and again after pregnancy. Rh immune globulin serves to clear any Rh-positive fetal cells from the mother’s circulation before she is sensitized. Rh immune globulin is also given after miscarriage, termination of pregnancy, or invasive procedures such as chorionic villus sampling or amniocentesis, in case any Rh-positive cells gained access to the mother’s circulation. The discovery of the Rh system and its role in hemolytic disease of the newborn has been a major contribution of genetics to medicine. At one time ranking as the most common human genetic disease among individuals of European ancestry, hemolytic disease of the newborn caused by Rh incompatibility is now relatively rare, but only because obstetricians remain vigilant, identify at-risk patients, and routinely give them Rh immune globulin to prevent sensitization.

Ethnic Differences in Disease Frequencies

Founder Effect

Thus one of the outcomes of the founder effect and genetic drift is that each population may be characterized by its own particular mutant alleles, as well as by an increase or decrease in specific diseases. The relative mobility of most present-day populations, in comparison with their ancestors of only a few generations ago, may reduce the effect of genetic drift in the future while increasing the effect of gene flow.

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Nov 27, 2016 | Posted by in GENERAL & FAMILY MEDICINE | Comments Off on Differences in the Frequency of Various Genetic Diseases

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