Mental retardation associated with "balanced" chromosome rearrangements

Area of Science:

• Human Genetics
• Developmental Biology
• Clinical Pediatrics

Background:

• Balanced chromosome rearrangements are known genetic factors associated with various developmental outcomes.
• Previous studies have explored the link between chromosomal abnormalities and intellectual disability, but specific types of rearrangements require further investigation.

Purpose of the Study:

• To investigate the prevalence of balanced chromosome rearrangements in children with intellectual disability compared to non-retarded psychiatric controls.
• To differentiate the contribution of Robertsonian and non-Robertsonian translocations, as well as de novo versus familial rearrangements, to intellectual disability.

Main Methods:

• Comparative analysis of chromosomal data from a cohort of intellectually disabled children and a control group of non-retarded psychiatric children.
• Meta-analysis of current findings with previously reported survey data on mentally retarded individuals and newborn populations.

Main Results:

• Seven of 455 intellectually disabled children had balanced chromosome rearrangements, compared to four of 1,679 controls (P < .05).
• The incidence of non-Robertsonian balanced rearrangements was five times higher in the intellectually disabled group than in newborn surveys.
• Robertsonian translocations were not significantly increased in the intellectually disabled group, and an increase in de novo rearrangements was observed, specifically for non-Robertsonian translocations.

Conclusions:

• Balanced non-Robertsonian chromosome rearrangements, particularly de novo events, are significantly associated with intellectual disability.
• The findings highlight the importance of detailed cytogenetic analysis in identifying the genetic underpinnings of intellectual disability.