The Association of Motor Skills and Adaptive Functioning in XXY/Klinefelter and XXYY Syndromes.

Klinefelter (XXY) and XXYY syndromes are genetic disorders in males characterized by additional sex chromosomes compared to the typical male karyotype of 46, XY. Both conditions have been previously associated with motor delays and motor skills deficits. We aimed to describe and compare motor skills in males with XXY and XXYY syndromes, and to analyze associations with age, cognitive abilities, and adaptive functioning. Sixty-four males with XXY and 46 males with XXYY, ages 4-20 were evaluated using the Beery Test of Visual Motor Integration and the Bruininks-Oseretsky Test of Motor Proficiency - 2nd Edition assessments, Vineland-2 adaptive scales, and cognitive testing. Motor coordination impairments were found in 39% of the males with XXY and 73% of the males with XXYY. Both groups showed strengths in visual perceptual skills. Males with XXYY had lower mean scores compared to males with XXY across all assessments. Fine motor dexterity and coordination deficits were common. There was a positive correlation between VMI scores and adaptive functioning. Occupational and physical therapists should be aware of the motor phenotype in XXY and XXYY both to aid in diagnosis of unidentified cases and to guide intervention.