CD20 molecule deficiency and carrier frequency: a village-based screening study

Area of Science:

• Immunology
• Genetics
• Public Health

Background:

• CD20 deficiency is a rare autosomal recessive inborn error of immunity (IEI).
• The only known affected individual is followed in our clinic, prompting investigation into potential carriers within their community.
• Consanguinity in the index patient's family suggested a higher likelihood of carriers in the village population.

Purpose of the Study:

• To evaluate clinical features of IEI in a village population.
• To identify individuals with CD20 mean fluorescence intensity (MFI) patterns indicative of putative carrier status for CD20 deficiency.
• To provide genetic counseling to identified individuals and families.

Main Methods:

• A cross-sectional screening study was conducted in Çukurbağ village.
• Participants completed questionnaires on IEI warning signs and familial relationships.
• Peripheral blood samples were analyzed by flow cytometry for CD19 and CD20 expression, classifying carriers by CD20 MFI <50% of controls.

Main Results:

• 145 individuals from 52 families were screened; 39.3% of relatives were consanguineous.
• No individuals with CD20 deficiency were found, but 14 participants (approx. 10%) showed reduced CD20 MFI, consistent with putative carrier status.
• Proposed CD20 MFI thresholds demonstrated high diagnostic performance for identifying putative carriers.

Conclusions:

• CD20 MFI is a more informative indicator than CD20 percentage for identifying putative carriers.
• Flow cytometry can serve as a rapid, preliminary screening tool in community settings.
• Molecular genetic testing is required for carrier status confirmation, and genetic counseling should be based on verified genotypic results.