Efficacy of MCAD screening in SIDS patients in Tennessee
Résumé fourni par la source
Medium chain acyl-CoA deficiency (MCAD) is an autosomal recessive disorder of fatty acid oxidation. While several mutations have been identified in the MCAD gene, an A to G point mutation affecting codon 329 (K329E) represents >90% of those reported. Unfortunately, the reported carrier frequency of this mutation varies greatly between populations which reduces the efficiency of neonatal screening. Mounting evidence suggests a correlation between MCAD deficiency and sudden infant death syndrome (SIDS). To determine the utility of MCAD screening in SIDS patients, we screened for the K329E mutation in DNA extracted from paraffin blocks retrieved from 75 consecutive SIDS patients. Two of 75 (2.7%) had DNA findings consistent with MCAD. One patient (A) was homozygous for K329E while a second patient (B) was heterozygous for K329E. Although the second abnormal MCAD allele has not yet been identified in this patient, in a clinical setting of SIDS, this patient may well represent a compound heterozygote. Subsequent to the analysis, the family of A was contacted and a newborn sib was found to be homozygous for K329E. Carnitine supplementation and frequent feedings were started and the child is doing well. Evaluation of family B is planned. Our finding of 2/75 SIDS patientsmore » with DNA findings suggestive of MCAD demonstrates the efficacy of MCAD screening in this population in contrast to that of newborn screening in TN where the estimated K329E carrier frequency is 1/249 and the calculated incidence of MCAD disease is approximately 1/248,000. Our study (1) confirms the finding of MCAD in 2 to 3% of consecutive SIDS patients, (2) utility of DNA testing in presymtomatic sibs of SIDS patients attributable to MCAD and (3) provides accurate recurrent risks and enables prenatal testing for SIDS families where the diagnosis of MCAD has been established.« less
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