Mapping 22q11.2 Gene Dosage Effects on Brain Morphometry

Area of Science:

• Neuroscience
• Genetics
• Developmental Biology

Background:

• Reciprocal chromosomal rearrangements at 22q11.2 are linked to neurodevelopmental disorders.
• 22q11.2 deletion is a major genetic risk for schizophrenia, while duplication is linked to autism.

Purpose of the Study:

• To investigate the effects of 22q11.2 gene dosage on human brain structure.
• To establish the first evidence of gene-dose-dependent brain phenotypes in this region.

Main Methods:

• Studied 143 human subjects: 66 with 22q11.2 deletions (22q-del), 21 with 22q11.2 duplications (22q-dup), and 56 controls.
• Analyzed intracranial volume, gray/white matter volume, cortical surface area, and thickness.
• Utilized novel subcortical shape analysis.

Main Results:

• Gene dosage positively correlated with intracranial volume, gray/white matter, and cortical surface area (deletion < control < duplication).
• Gene dosage negatively correlated with mean cortical thickness (deletion > control > duplication).
• Observed widespread cortical surface area changes and localized thickness differences, extending to subcortical regions like the hippocampus, caudate, and amygdala.

Conclusions:

• The 22q11.2 locus exhibits gene-dose-dependent effects on brain morphology.
• Copy number variation at 22q11.2 impacts brain structure early in development, affecting cortical surface area most broadly.
• Findings highlight the role of 22q11.2 in typical brain development and neurodevelopmental disorders.