Abstract
XLA is characterized by hypogammaglobulinemia and absent B cells, but normal numbers of pre-B cells. Atypical cases of XLA have been reported in which immunoglobulin concentrations are higher than expected or pre-B cells are absent. We have recently demonstrated that B cells from obligate carriers of typical XLA selectively use the X chromosome that does not carry the gene defect as the active X. To extend this observation, we developed a technique that combines the production of somatic cell hybrids that retain the active X, with the use of X-linked RFLPs that permit the distinction of the two X chromosomes. This technique, which allows the identification of the active X in cells from any woman, was used to study an obligate carrier and 4 women at risk in families with typical XLA. We also studied the mother of a boy with atypical XLA who has low numbers of B cells, absent IgA and IgM but normal IgG and no family history. All 10 B cell hybrids from the known carrier used the same X as the active X; 3 of the 4 women at risk also demonstrated nonrandom X chromosome inactivation in B cells; 7 of the hybrids from the last woman used one X chromosome and 8 used the other, indicating that this woman is not a carrier. All 19 B cell hybrids from the mother of the sporadic case also used the same X, indicating that this woman is a carrier for an X-linked form of disease. These results show that this technique can be used for carrier detection in both sporadic cases of XLA and in XLA pedigrees. Further, by increasing the number of individuals who are informative for mapping in atypical XLA families, we will be able to examine heterogeneity of XLA.
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Conley, M., Puck, J. CARRIER DETECTION IN TYPICAL AND ATYPICAL X-LINKED AGAMMAGLOBULINEMIA (XLA). Pediatr Res 21 (Suppl 4), 310 (1987). https://doi.org/10.1203/00006450-198704010-00857
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DOI: https://doi.org/10.1203/00006450-198704010-00857