Minor physical anomalies in neurodevelopmental disorders: a twin study

Area of Science:

• Developmental biology
• Genetics
• Clinical psychology

Background:

• Minor physical anomalies (MPAs) are subtle anatomical variations linked to altered embryogenesis.
• MPAs are more prevalent in neurodevelopmental disorders (NDDs) than in typical development.
• Further research on MPAs in NDDs, particularly twin studies, is needed to control for familial factors.

Purpose of the Study:

• To investigate the association between MPAs and NDDs, including autism spectrum disorder (ASD) and attention-deficit/hyperactivity disorder (ADHD).
• To examine the relationship between the number of MPAs and zygosity within twin pairs.
• To identify specific MPAs associated with ASD.

Main Methods:

• Clinical assessments of 116 twins (61 NDD, 55 controls) from 51 monozygotic and 7 dizygotic pairs.
• Statistical analysis to determine the association between MPAs and NDD diagnoses and traits.
• Investigation of intrapair correlations of MPAs based on zygosity.

Main Results:

• A significant association was found between MPAs and ASD diagnosis and autistic traits.
• MPAs were not significantly associated with NDDs in general or ADHD.
• Specific MPAs in ASD included overweight, hypermobility, pes planus, straight eyebrows, vision impairment, arachnodactyly/long toes, long eyelashes, and microtia.
• A high correlation in the number of MPAs was observed within monozygotic twin pairs.

Conclusions:

• MPAs are more frequent in individuals with ASD, suggesting a potential genetic influence.
• MPAs may serve as indicators for early detection of ASD.
• Further exploration of MPAs' utility in identifying individuals at increased risk for ASD is warranted.