Dados do Trabalho

Título

Cognitive profile and school performance of eight school-age boys with MAOA-uVNTR*2R allele

Apresentação do caso

In the present study, we describe the cognitive correlates of boys having MAOA_LPR*2R allele, ascertained in a sample of school children with normal intelligence, not referred for behavior disorders. Participants were eight boys, attending from 2nd to 5th grades in state-run schools. They were identified among 712 children with typical general cognitive ability, genotyped for MAOA_LPR polymorphism. Participants were assessed with general intelligence; mathematics and spelling achievement; and, verbal and visuospatial working memory tests. Neuropsychological performance was compared to published norms using 1-SD below the mean as a cutoff for low performance. Intelligence of boys with MAOA_LPR*2R allele varied from above average to low average. Five boys with MAOA_LPR*2R allele had low mathematics achievement and three presented additional difficulties with spelling. Four boys had low short-term and working memory performance.

Discussão

MAOA is one of the enzymes involved in the neurotransmitter metabolism, helping catabolize serotonin, dopamine, epinephrine, and norepinephrine. One of the polymorphisms described in the MAOA gene (MAOA_LPR) is a variable number of tandem repeats, presenting alleles 2R (R, for repeats), 3R, 3.5R, 4R, and 5R. Higher enzyme activity has been described for the 3.5R and 4R alleles. Low activity MAOA alleles (2R, 3R, and 5R) have been associated with antisocial disorders, such as criminal behavior (stabbing, rape attempt, exhibitionism, ransom, and shooting). Less attention has been paid to the cognitive functioning of individuals with different MAOA alleles. This is the first study describing cognitive correlates and school performance in boys having MAOA_LPR*2R allele. Learning difficulties, particularly in math, and low working memory performance were observed in boys having this allele.

Comentários finais

In the present study we described the cognitive phenotype associated with the less frequent, low enzyme activity allele, MAOA_LPR*2R. Having this allele, and therefore, probably low MAO-A activity, does not necessarily imply low intelligence or low school performance. However, learning difficulties and low working memory were observed in these cases. This suggests a role of MAOA in learning difficulties.

Palavras-Chave

MAOA-uVNTR*2R, working memory, learning difficulty