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Detection of the carrier state in combined immunodeficiency disease associated with adenosine deaminase deficiency
Insights
Detecting carriers of severe combined immunodeficiency disease (CID) is possible by measuring red blood cell adenosine deaminase (ADA) activity. This study confirms ADA deficiency as an autosomal recessive disorder, aiding in genetic diagnosis.
Area of Science:
- Immunology
- Genetics
- Biochemistry
Background:
- Severe combined immunodeficiency disease (CID) is a group of rare genetic disorders.
- Adenosine deaminase (ADA) deficiency is a known cause of CID.
- Identifying heterozygote carriers is crucial for genetic counseling and family planning.
Purpose of the Study:
- To investigate the utility of measuring red blood cell adenosine deaminase (ADA) activity for detecting heterozygote carriers of ADA deficiency.
- To establish the inheritance pattern of CID associated with ADA deficiency.
Main Methods:
- Analysis of red blood cell ADA activity in a large pedigree with a child diagnosed with ADA deficiency-associated CID.
- Comparison of ADA activity levels in at-risk individuals across three generations with a control population.
- Statistical analysis to determine confidence in identifying heterozygotes.
Main Results:
- Nine out of 17 at-risk individuals exhibited decreased red blood cell ADA activity.
- The mean ADA activity in identified heterozygotes was approximately half that of the control population (19.2 U/g Hb vs. 36.1 U/g Hb).
- Statistical analysis indicated a 90% confidence level in identifying heterozygotes within high-risk families.
Conclusions:
- Measuring red blood cell ADA activity is an effective method for identifying heterozygote carriers of ADA deficiency.
- This study confirms that ADA deficiency-associated CID is an autosomal recessive disorder.
- The findings support the use of enzymatic assays for carrier screening in families with a history of ADA deficiency-associated CID.
Abstract:
A large pedigree containing a child with severe combined immunodeficiency disease (CID) associated with adenosine deaminase (ADA) deficiency was investigated to ascertain if heterozygotes could be detected by measuring red cell ADA activity. 9 of 17 individuals in three generations who were at risk for being heterozygous had decreased red cell ADA activity. This genetic information establishes one form of CID as an autosomal recessive disorder. The identified heterozygote population had a mean ADA value of 19.2 U/g hemoglobin (0.95 confidence interval; 14.0 to 24.4 U/g hemoglobin), which was approximately one-half the mean, 36.1 U/g hemoglobin, of a randomly selected control population (0.95 confidence interval; 22.5-58.1 U/g hemoglobin). Statistical comparisons of the heterozygotes to the normal population indicates that within a high-risk family heterozygotes may be identified with 90% confidence.
