Differential expression of Handedness and Scalp Hair-whorl direction associated to writing disturbances in school children from La Rioja province of Argentine.

RATTI SILVIA G.; CORDOBA P; REARTE SN; ALVAREZ EO

International Journal of Neuroprotection and Neuroregeneration

Año: 2007 vol. 4 p. 52 - 60

Three phenotypic characteristics (handedness, scalp hair-whorl direction, and writing capacity) thought to be linked to the HSR (Hand Skill Relative) chromosome locus were studied in school children in two geographical regions from Argentine. Regions were classified according to the existence of mineral mines and mountain sierras, prevalent in “Region 2” and absent in “Region 1”. A total sample of 547 children was selected, 317 for Region 1 and 230 for Region 2. Handedness was evaluated following the Edinburgh Hand Inventory. Brain asymmetry was indirectly evaluated by inspection of the scalp hair-whorl direction (clockwise direction and non clockwise direction), and writing capacity by examining children’s written responses after dictation of a selective text for detection of dyslexic disturbances. Results in Region 2 show alterations compared to Region 1 in all three phenotypic characteristics. An increase in the ratio of right handedness to non right handedness (8.32 Vs 19.9), a decrease in the ratio of clockwise scalp hair-whorl direction to non-clockwise direction (3.03 Vs 2.06), and a decrease in the ratio of without writing disturbances to writing disturbances (23.4 Vs 0.81) were observed in Region 2. Study of the association of phenotypic characters (handedness versus scalp hair-whorl direction; scalp hair-whorl direction versus writing disturbances; and handedness versus writing disturbances) suggests that (i) right handedness appears to be associated to hair-whorl direction but not to be associated to this trait in non-right handers; (ii), Handedness was found to be associated to writing disturbances, and (iii)  brain asymmetry appears to be related to writing disturbances. It was concluded that some factor present in Region 2 not presently identified could be influencing the phenotypic linked expression of the HSR gene in La Rioja, Argentine.