Cytogenetic abnormalities in attention-deficit/hyperactivity disorder

Area of Science:

• Genetics
• Pediatrics
• Neurodevelopmental Disorders

Background:

• Attention-deficit/hyperactivity disorder (ADHD) is a common neurodevelopmental disorder in children.
• Cytogenetic abnormalities are sometimes associated with neurodevelopmental disorders.
• Fragile X syndrome and velocardiofacial syndrome are specific genetic conditions that can present with developmental challenges.

Purpose of the Study:

• To determine the prevalence of fragile X syndrome, velocardiofacial syndrome, and other cytogenetic abnormalities in children diagnosed with ADHD.
• To evaluate the clinical utility of genetic screening in this population.

Main Methods:

• A cohort of 100 children with combined-type ADHD and normal intelligence underwent genetic analysis.
• Testing included fragile X mutation analysis, 22q11.2 microdeletion testing for velocardiofacial syndrome, and high-resolution chromosomal banding.
• Blood samples were used for all analyses.

Main Results:

• One girl with ADHD exhibited sex chromosome aneuploidy (47,XXX).
• One boy carried a premutation allele for fragile X, but no full mutation was detected.
• All subjects tested negative for the 22q11.2 microdeletion.
• The observed abnormalities did not exceed expected frequencies by chance.

Conclusions:

• Routine genetic screening for fragile X syndrome and velocardiofacial syndrome is not clinically indicated for children with ADHD and normal intelligence, absent specific clinical indicators or family history.
• These genetic tests are not recommended as part of broader genetic investigations for ADHD in this patient group.