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Alpha-1-antitrypsin protease inhibitor (Pi) phenotypes in Down's syndrome patients and their parents

L Bufton, R E Magenis, E W Lovrien

    Clinical Genetics
    |January 1, 1982
    PubMed

    Insights

    Individuals with Down syndrome and their parents show a higher frequency of Alpha-1-antitrypsin (AAT) variant phenotypes. This genetic variation in AAT is more common in Down syndrome families than in control groups.

    Area of Science:

    • Genetics
    • Human Biology

    Background:

    • Down syndrome, a genetic disorder caused by trisomy 21, is associated with various health complications.
    • Alpha-1-antitrypsin (AAT) is a proteinase inhibitor with known genetic variations (phenotypes).

    Purpose of the Study:

    • To investigate the frequency of Alpha-1-antitrypsin (AAT) variant phenotypes in families with Down syndrome.
    • To determine if AAT variant phenotypes correlate with the origin of the extra chromosome 21 or maternal age.

    Main Methods:

    • Serum samples from 121 Down syndrome families were analyzed for AAT phenotypes.
    • Phenotype frequencies were compared between affected individuals, their parents, and control groups.
    • Parental origin of chromosome 21 and maternal age were considered in relation to AAT phenotypes.

    Main Results:

    • A significantly higher frequency of AAT variant (non-M) phenotypes was observed in parents (15%) and affected children (19%) of Down syndrome families compared to controls (8-10%, p < 0.001).
    • Variant AAT phenotypes were identified in parents of Down syndrome patients.
    • No simple correlation was found between AAT variant inheritance and the parental origin of the extra chromosome 21 or maternal age.

    Conclusions:

    • There is an increased prevalence of Alpha-1-antitrypsin variant phenotypes within Down syndrome families.
    • The observed increase in AAT variants in Down syndrome families appears independent of the genetic mechanism of nondisjunction and maternal age.

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