SAN DIEGO – Verbal and full-scale intelligence quotient measures for males with XXYY syndrome are significantly lower than for males with XXY syndrome, but performance IQ is not significantly different between the two groups, results from a small study show.
Although previous reports have noted more cognitive and behavioral problems in XXYY males than in XXY males, this is the first study to directly compare the cognitive and behavioral features of the two syndromes, Dr. Nicole R. Tartaglia said at the annual meeting of the Society for Developmental and Behavioral Pediatrics.
She and her associates recruited 16 males with XXYY syndrome and 9 males with XXY syndrome from national organizations for patients with sex chromosome aneuploidy.
The males were 5–20 years old, and all of the families underwent a clinical interview and completed the Behavioral Assessment System tool.
The investigators obtained information on cognitive function either by reviewing patients' medical records or by administering to the subjects the children's intelligence scale in the Wechsler Abbreviated Scale of Intelligence.
XXYY males were found to have significantly lower verbal and full-scale IQs compared with XXY males, but there were no significant differences between the two groups on mean performance IQ scores, said Dr. Tartaglia, who is a fellow in the department of pediatrics at the University of California, Davis.
XXYY males were more likely than their XXY counterparts to have problems with hyperactivity, aggression, conduct, and depression, she said.
XXYY males were also more likely to have significantly lower adaptive functioning than were males with XXY.
Dr. Tartaglia noted that a limitation of the study is its small sample size.
XXY syndrome occurs in about 1 in 800 males whereas XXYY is much less common, occurring in about 1 in 17,000 males.
Doug Brunk