Abstract
Three approaches to the prenatal diagnosis of the severe, early onset form of hypophosphatasia, a rare inborn error of metabolism, were investigated in 2 pregnancies of a family with a previous history of the disease. Two of these approaches, ultrasonography and the determination of the bone and liver isozyme activity of alkaline phosphatase (ALP) in cultured amniotic fluid cells have proven useful diagnostically. The third approach, assay of the bone and liver isozyme activity or total activity in supernatant amniotic fluid was not found to be informative.
In 1 pregnancy, the failure of ultrasonography at 16, 18, and 19 weeks gestation to reveal a well defined fetal skull, when the level. of alpha-fetoprotein in the amniotic fluid was normal, suggested hypophosphatasia. This diagnosis was supported by the finding that cultured amniotic fluid cells from this fetus had an ALP specific activity which was 4% of the mean of 68 control cultures and much less than the lowest control value.
A subsequent normal sibling who has heterozygous serum levels of ALP had normal ultrasound findings and normal cultured amniotic fluid cell enzyme activities. The study has emphasized the differences in tissue specific ALP isozyme composition of amnio-otic fluid supernatant and cultured cells. These differences are crucial in the diagnosis of this defect of bone and liver ALP.
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Mulivor, R., Mennuti, M., Harris, H. et al. 546 PRENATAL DIAGNOSIS OF HYPOPHOSPHATASIA. Pediatr Res 12 (Suppl 4), 454 (1978). https://doi.org/10.1203/00006450-197804001-00551
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DOI: https://doi.org/10.1203/00006450-197804001-00551
