Background

Some disease processes are more prevalent in specific races vs others and present more frequently in clinical practice. Sickle cell disease (SCD), for example, is prevalent in African-American and African populations, as well as in populations from descendants with Mediterranean heritage.7 Tay-sachs disease (TSD) is more likely to occur among people of Ashkenazi (Eastern and Central European) Jewish or French-Canadian ancestry. Cystic fibrosis (CF) is common among people of European lineage. Alpha thalassemia mostly affects people of Southeast Asian, Indian, Chinese, or Filipino descent, whereas beta thalassemia most often affects people who are of Mediterranean (Greek, Italian, and Middle Eastern), Asian, or African descent.7,8 


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Historical context

In the last few decades since the decoding of the human genome, a growing wealth of data have made it clear that the concept of race and genetics is complex.9 The analysis of genomes around the world confirms that there is a biologic basis for race, despite statements to the contrary from some social science organizations.9 For example, in mixed races such as African-Americans, geneticists can now track a person’s genome and assign each segment to African or European ancestors. This analysis would be impossible if race did not have some basis in genetic and biologic component.9


Prevalence and incidence of conditions

The demographics of race throughout the world population vary: African (11.8%), Asian (47.8%), European (15.4%), Mixed races (4.9%), Native American (0.9%), Middle Eastern (10.9%), Oceanic (3.4%), and other (5%).10 Similarly, in the United States, demographics of race throughout the population vary: whites (61%), blacks (12%), Hispanics (18%), Asian (6%), and American/Alaska Native (1%).11 

Globally, approximately 5% of children are born with genetic disorders,12 whereas in the US, approximately 3% of children are born with genetic disorders.13 The most commonly reported genetic conditions are SCD, TSD, CF, and thalassemia. These disorders have an autosomal recessive mode of inheritance and have higher carrier rates in specific races or patient populations.14 

In the US, SCD occurs in nearly 1 of every 365 African American births and is estimated to affect about 100,000 Americans.12 Approximately 1 in 13 African Americans is born with sickle cell trait (SCT).12 Sickle cell trait is an inherited sickle cell gene from one or both parents.15 SCT is not a disease and people with SCT do not show symptoms of SCD and are able to live a normal life.15 The incidence of SCT in the US is estimated as 73.1 cases per 1,000 black newborns, 2.2 cases per 1,000 Asian or Pacific Islander newborns, 6.9 cases per 1,000 Hispanic newborns, and 3.0 cases per 1,000 white newborns.12 

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The frequency of TSD is much higher in the Ashkenazi Jews of Eastern European origin than in others.16 Approximately 1 of every 27 Jewish people in the US is a carrier of the TSD gene.16 Among Jewish people of Sephardic origin, the carrier rate is about 1 in 250.16 French-Canadians and the Cajun community of Louisiana have the same carrier rate as Ashkenazi Jews, 1 in 27.  Also, people of Irish ancestry have an increased risk for the TSD gene mutation.16 Current research studies indicate that among Irish Americans, the carrier rate is about 1 in 50.16 The incidence of CF varies across around the world. Although it is underdiagnosed in Asia, existing evidence indicates that the prevalence of CF is rare among this population. In the European Union, 1 in 2,000 to 3,000 newborns is found to be affected by CF.16 In the US, the incidence of CF is reported to be 1 in every 3,500 births.16

The prevalence of thalassemia varies with geographic locations. It is estimated in India that 0.37 per 1,000 fetuses have a hemoglobin disorder.17 Beta thalassemia, the most severe form of thalassemia, affects at least 1,000 people in the US.18