Pilot study for subgroup classification for autism spectrum disorder based on dysmorphology and physical measurements in Chinese children

Abstract

OBJECTIVE: Autism spectrum disorder (ASD) is a complex neurodevelopmental disorder, characterized by deficits in three main domains: communication, social skills and repetitive/stereotyped behaviours. The impact of ASD significantly varies between individuals, along the continuum of severity in its presentation, symptoms and treatment outcome. Currently there is no cure for ASD, and the clinical variability still remains. Hence the search to unravel homogeneous subgroups to facilitate ASD research, towards providing a better understanding of the entire disorder. DESIGN: Descriptive study. METHOD: In this study, a norm of physical measurements including height, weight, head circumference, ear length, outer and inner canthus, interpupillary distance, philtrum and hand and foot length was collected from 658 typical developing (TD) Chinese children (mean age=4y 2mo) and 80 Chinese ASD children (mean age=4y 4mo). We then attempted to find subgroups within ASD participants based on physical abnormalities and generalized dysmorphology; individuals were classified as dysmorphic with the Autism Dysmorphology Measure (ADM) from dysmorphic examination coding of 12 body regions. RESULTS: Our results show that there was a significant difference between TD and ASD groups in measurements for head circumference (P=0.009), outer (P=0.021) and inner (P=0.021) canthus, philtrum length (P=0.003) and right (P=0.023) and left (P=0.20) foot length. Within the 80 ASD patients, 37 (46.25%) were classified as dysmorphic (P=0.00). CONCLUSION: This study attempts to identify subgroups within ASD patients based on physical measurements and dysmorphology examinations. The identification of homogeneous subgroups within ASD will benefit the development of future diagnosis, referral and treatment plans.