The curious variability in risks associated with alpha-thalassemia

Not all carriers of alpha-thalassemia have the same disease transmission outcomes. Read more about how the ethnicity with the highest carrier frequency is not the ethnicity with the highest risk of having an affected child.

The purpose of this study was to identify which ethnic population carriers of alpha-thalassemia are at the highest risk of disease transmission and if there is value in pan-ethnic testing to identify alpha-thalassemia carriers.

We performed a retrospective analysis of >75,000 patients referred to our laboratory for Preparent® carrier testing. Testing included multiplex PCR followed by gel electrophoresis and analysis to identify 7 common α-globin deletions, including -α3.7, -α4.2, --SEA, --FIL, --MED, --α20.5, and --THAI.

What did we find?

  • The Asian population was at the highest risk of transmitting Hemoglobin Bart and Hemoglobin H disease.1
  • While the highest positivity rate was seen in the African American/Black population, the silent carriers in this population far outweigh the disease transmission carriers.1
Positive carriers were identified at an unexpectedly high frequency in relatively understudied ethnic backgrounds, like Native American and Hispanic populations, giving further impetus to test patients of all ethnicities.1
This research was presented at the 2018 American Society of Human Genetics (ASHG) Annual Meeting. Download the poster


  1. Fernandes et al. Retrospective analysis of a patient cohort referred for carrier testing for alpha thalassemia. Poster presented at ASHG 2018. San Diego, CA.