This article presents a critical review of literature on genetics of mental …

• Abstract
• Idiopathic mental retardation
• Single-gene defects
• Fragile X syndrome
• Chromosomal abnormalities
• Down syndrome
• Microdeletion syndromes
• Prader-Willi syndrome
• Angelman syndrome
• Sex chromosome anomalies
• Turner's syndrome
• Klinefelter's syndrome
• Conclusions
• References
• Figures

Turner's syndrome affects 1 in 2000 to 1 in 5000 females. It is characterized by the complete or partial absence of one X-chromosome (45XO). The clinical features include short stature, a webbed neck, increased carrying angle of the elbow, failure to develop secondary sexual characteristics and visuo-spatial deficits. Interesting recent data suggest the X-chromosome might also play an important role for other sorts of cognitive skills, which facilitate social interaction. Girls tend to show superior levels of skills such as the ability to respond to cues in the behaviour of others, to inhibit distractions and to develop strategies of action compared with boys. Females affected by Turner's syndrome, whose X-chromosome is of maternal origin show poorer social cognitive skills than those who possess a paternally derived X-chromosome.[35]