Risk analyses for the cognitive phenotype in Turner's syndrome: evidence of familial influence as a decisive factor.

The interindividual varying cognitive performance in female patients with Turner's syndrome has usually been attributed to the interindividual varying mosaicism with a consecutive variable loss of X-chromosome DNA or to secondary risk factors such as estrogen deficiency owing to ovarian failure. The aim of our study was to determine the specific impact of X chromosome-related features and associated risk factors, on the one hand and familial influences, on the other hand on the interindividual variation in the cognitive phenotype. One hundred and one subjects with Turner's syndrome and 53 sisters as controls for familial influences were examined by comparing the cognitive information processing abilities (Kaufmann Assessment Battery for Children [K-ABC]).

Familial factors and hearing impairment modulate the neuromotor phenotype in Turner syndrome.

In Turner syndrome (TS), an X-chromosomal anomaly characterised by total or partial loss of the second X-chromosome, muscle hypotonia, and lower proficiency in fine and gross motor skills have been described. It is assumed that the neuromotor phenotype in TS is linked with X-chromosomal factors (individual mosaicism) and with the oestrogen deficiency due to streak gonads. From studies in normal populations, a further risk factor may be recurrent otitis media (OM), which occurs frequently in TS, often in combination with hearing impairment (HI).