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Carrier detection and rapid newborn diagnostic test for the common Y393N maple syrup urine disease allele by PCR‐RFLP: Culturally permissible testing in the Mennonite community
Author(s) -
LoveGregory L. D.,
Dyer J. A.,
Grasela J.,
Hillman R. E.,
Phillips C. L.
Publication year - 2001
Publication title -
journal of inherited metabolic disease
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.462
H-Index - 102
eISSN - 1573-2665
pISSN - 0141-8955
DOI - 10.1023/a:1010517005001
Subject(s) - maple syrup urine disease , newborn screening , allele , heterozygote advantage , compound heterozygosity , urine , restriction fragment length polymorphism , biology , genetics , medicine , gastroenterology , genotype , amino acid , gene , leucine
The turnaround time for diagnosis of maple syrup urine disease (MSUD) by classic serum amino acid analyses often requires 3–4 days. This is due to the need for branched‐chain amino acids (BCAA) to accumulate in the serum of the newborn before testing. The accumulation of BCAAs in infants with MSUD during this time increases the risk of the infant becoming clinically symptomatic. We have developed a noninvasive DNA‐based mismatch PCR‐RFLP assay for the Y393N BCKDHA allele (E1α gene of the branched chain α‐keto acid dehydrogenase complex), the primary cause of MSUD in Old Order Mennonite communities. The homozygosity and high frequency of this mutation in the Mennonite community and its prevalence in compound heterozygote non‐Mennonite MSUD patients is of significance. We describe carrier testing, present the results of nine newborns diagnostically evaluated for the Y393N BCKDHA allele, and demonstrate the efficacy of this PCR‐RFLP assay for determining clinical status within 24 h after birth. Analyses within the first 24h of life allow for immediate diagnosis and treatment of infants homozygous for the Y393N MSUD defect. This is a significant improvement over the time required by current serum amino acid analysis methods.