Medium-chain acyl CoA dehydrogenase deficiency: Its relationship to SIDS and the impact on genetic counseling

Sudden infant death syndrome (SIDS) is defined as the sudden and unexpected death of an apparently healthy infant under 1 year of age. Routine autopsies often provide few clues as to the cause of death and rarely include a biochemical evaluation. Genetic counseling for SIDS can be difficult as recurrence risks vary depending on the age at death and the number of deaths which have occurred in the family. Biochemical disorders may account for up to 5% of SIDS. Of the metabolic disorders known to be involved in SIDS, the most commonly found is medium-chain acyl CoA dehydrogenase deficiency (MCAD). MCAD is an autosomal recessive disorder of fatty acid oxidation which accounts for up to 1% of SIDS. For some families, the addition of a postmortem biochemical investigation can identify an unsuspected metabolic disorder as the cause of death. Once the diagnosis is established, accurate genetic counseling can then be provided. Metabolic testing of the surviving siblings of victims of sudden death, and the subsequent identification of those due to MCAD can prevent the tragedy of recurrent SIDS in some families. In addition, screening the survivors of an acute life threatening event (ALTE) may also prevent a recurrence.     

Neuropsychological Functioning in Children with Medium Chain Acyl Coenzyme A Dehydrogenase Deficiency (MCADD): The Impact of Early Diagnosis and Screening on Outcome

Children with medium chain acyl coenzyme A dehydrogenase deficiency (MCADD) have been reported to be at high risk for neurocognitive deficits. However this has not been systematically studied and little is known about the exact nature of neuropsychological sequelae or of the impact of early diagnosis and screening on outcome. We examined cognitive and adaptive outcome in children with MCADD (N?=?38, age range: 2 years, 2 months – 10 years, 3 months) diagnosed either through a newborn screening program (tandem mass spectrometry/MSMS) or upon clinical presentation. There was no evidence of overall intellectual impairment in either groups but there was some suggestion of poorer verbal and specific executive functioning (i.e., planning) abilities in the unscreened cohorts. Adaptive functioning was relatively intact with the exception of reduced Daily Living Skills in both our screened and unscreened groups. Early diagnosis and greater number of hospitalizations were related to higher verbal, communication, and socialization skills. Overall, our results highlight the importance of early diagnosis and management for children with MCADD.     

Genetic polymorphisms of alcohol-metabolizing enzymes and their association with alcoholism risk,personality and anthropometric traits among Malaysian university students

Three single nucleotide polymorphisms (SNPs) in alcohol-metabolizing genes – ADH1B (Arg47His), ADH1C (Ile350Val) and ALDH2 (Glu504Lys) have been extensively associated with flush reaction and alcoholism. Therefore, we investigated the association of these three SNPs with alcohol-induced reactions (AIRs), alcoholism risk, personality and anthropometric traits among Malaysian university students. AIRs, Self-Rating of the Effects of Alcohol (SRE) and Ten-Item Personality were surveyed, anthropometric measurements and DNA samples were taken. Among 264 valid drinkers (111 males, 153 females; 229 ethnic Chinese, 35 ethnic Indians), the minor allele frequencies for ADH1B, ADH1C, ALDH2 among Chinese/Indians were .45/.07, .33/.40, .32/.41, respectively; distribution of ADH1B alleles significantly different between ethnicities. Current/former experiences of flushing, hives, heart palpitations after alcohol consumption; and sleepiness, headache reactions, early and overall SRE were significantly different between ethnicities and genders, respectively. Overall SRE score was associated with ADH1C and ALDH2 alleles. ‘Openness to Experiences’ was associated with ALDH2 genotypes and alleles; Glu/Glu or Glu carriers showed significantly higher means. ADH1B Arg/Arg and Arg carriers showed significantly higher total body and subcutaneous fats but association was abolished after controlling for ethnicity. In conclusion, gender and ethnicity, but not alcohol-metabolizing gene variants, play a role in influencing the manifestation of AIRs.