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An ADA deficiency resolves itself
WASHINGTON-An inherited deficiency of adenosine deaminase may not be eternal.
A now-healthy 12-year-old boy who had paternal and maternal ADA mutations at birth has apparently undergone a spontaneous reversion to normal, says NYU's Dr. Rochelle Hirschhorn. A sibling with a suspected ADA mutation died of severe combined immunodeficiency at age 3.
In the boy's early years, a paternally transmitted splice-site mutation was found in all cell types examined, Dr. Hirschhorn told the combined clinical research societies meeting here. But a maternally transmitted deleterious missense mutation was in peripheral blood DNA only, not in B-lymphoid cells. Later, clones lacking the maternal mutation were common.
The boy had a mild clinical course, with substantial residual ADA activity in lymphoid cells. For religious reasons, he had no therapy.
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For a third, a genotype is a mystery
WASHINGTON-The cause of more than a third of SCID cases isn't known.
Mutations in the genes for adenosine deaminase, Janus kinase 3, and certain interleukin receptors account for 60 of 95 consecutive SCID infants seen at Duke in the past 30 years. But the molecular basis for 35 cases in this largest series reported in the U.S. hasn't been discovered, says Dr. Rebecca Buckley.
All but 15 patients were male. Seventy-four were white, 13 black, and eight Hispanic. Six were Jak3-deficient, 16 lacked ADA, and 38 had X-linked SCID. ADA-deficient patients were most lacking in total lymphocytes, she told the Society for Pediatric Research meeting here.
The Jak3 and X-linked patients had the most B cells and the fewest natural killer cells. All 95 infants were profoundly deficient in T cells, but NK function was normal in 25 of 60 tested in the various groups. -Elsie Rosner
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