Abstract
A presumptive intrauterine diagnosis of β-ketothiolase deficiency based on decreased ability to oxidize isoleucine by amniotic fluid cells was made in the sib of a known case. The diagnosis has been supported in the infant by studies of his urine metabolites, which show α-methyl β-OH butyrate, α-methyl acetoacetate, and tiglic acid. On a low protein diet the child shows few clinical symptoms at six months of age and does not have hyperglycinemia.
We had previously reported that the first sibling's fibroblasts had decreased isoleucine transport and were unable to concentrate isoleucine after several passages in culture. The new infant's cells show a more severe transport defect even in early culture. The transport defect appears to be loss of the high affinity transport system (Km ∼ 0.01 mM) for neutral amino acids seen in normal cell lines. Whether these combined defects represent close linkage of two genes or a secondary transport deficiency due to the biochemical lesion is unclear.
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Otto, E., Keating, J. & Hillman, R. COEXISTENCE OF β-KETOTHIOLASE DEFICIENCY AND A NEUTRAL AMINO ACID TRANSPORT DEFECT IN TWO SIBLINGS. Pediatr Res 11, 461 (1977). https://doi.org/10.1203/00006450-197704000-00550
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DOI: https://doi.org/10.1203/00006450-197704000-00550