title: Association between a functional polymorphism in the MAOA gene and sudden infant death syndrome.
abstract: OBJECTIVE
  Abnormalities in the serotonergic as well as the noradrenergic neuronal systems are believed to contribute to sudden infant death syndrome (SIDS). The X-chromosomal monoamine oxidase A (MAOA) gene is of importance for both systems and up to now no systematic study on a functional polymorphism in this gene has been performed in a sufficiently large group.
  
  
  METHODS
  We investigated a functional MAOA promoter length polymorphism in 156 white SIDS cases and 260 gender- and age-matched control subjects by using capillary electrophoresis and fluorescence dye labeled primers.
  
  
  RESULTS
  The pooled low-expressing alleles *2 and *3 were more frequent in the 99 male SIDS cases than in 161 male control subjects (44.4% vs 25.5%). However, there were no differences in female cases. The frequency of low expression alleles varied significantly with the age at death and were significantly more frequent in children who died between an age of 46 and 154 days than at an older age (54.9% vs 22.6%).
  
  
  CONCLUSIONS
  Our results indicate a relationship between SIDS and the MAOA genotype in boys via influencing serotonergic and noradrenergic neurons in the brainstem. This locus is the first X-chromosomal locus associated with SIDS. Our results support the theory that abnormalities in the brainstem contribute to a subset of SIDS, at least in boys. Moreover, we argue that not only the serotonergic system but also other neuronal systems, among those the noradrenergic one, are involved.
authors.affiliation: Institute of Legal Medicine, Medical University Hannover, Hannover, Germany. klintschar.michael@mh-hannover.de
authors.forename: Michael
authors.initials: M
authors.lastname: Klintschar
authors.forename: Christian
authors.initials: C
authors.lastname: Heimbold
mesh_terms: D000483:Alleles; D016022:Case-Control Studies; D005260:Female; D020022:Genetic Predisposition to Disease / Q000453:epidemiology*; D005858:Germany; D006801:Humans; D015994:Incidence; D007226:Infant Mortality; D007231:Infant, Newborn; D008297:Male; D008995:Monoamine Oxidase / Q000235:genetics*; D016133:Polymerase Chain Reaction / Q000379:methods; D011110:Polymorphism, Genetic; D011401:Promoter Regions, Genetic / Q000235:genetics; D018570:Risk Assessment; D012680:Sensitivity and Specificity; D012737:Sex Factors; D013398:Sudden Infant Death / Q000453:epidemiology / Q000235:genetics*; D044465:White People / Q000235:genetics
chemical_list: D008995:Monoamine Oxidase