Craniofacial Anthropometry and Facial Indices among Nigerian Individuals with Down Syndrome: A Comparative Cross-Sectional Study

Down syndrome is associated with characteristic craniofacial morphology, yet population-specific anthropometric data from Nigeria remain limited. This study compared craniofacial dimensions and facial indices between Nigerian individuals with Down syndrome and apparently healthy controls. A comparative cross-sectional study conducted in Jos, Nigeria, included 30 individuals with Down syndrome and 60 controls aged 4–24 years. Bizygomatic breadth, morphological facial height, and morphological upper facial height were measured using direct anthropometry. Morphological facial and upper facial indices were calculated from these measurements. Group differences were assessed using independent-samples t-tests, with mean differences, 95% confidence intervals, and Cohen’s d reported. Bizygomatic breadth was lower among participants with Down syndrome than among controls (118.4 ± 9.73 versus 121.5 ± 8.59 mm), although the difference was not statistically significant (p = .126; d = 0.35). Morphological facial height (98.67 ± 9.58 versus 103.8 ± 9.02 mm; p = .015; d = 0.55) and morphological upper facial height (54.87 ± 6.27 versus 59.40 ± 5.12 mm; p < .001; d = 0.82) were significantly lower in the Down syndrome group. Morphological facial and upper facial indices were also significantly lower (p = .009 and p < .001, respectively), with the largest effect observed for the morphological upper facial index (d = 1.04). Overall, differences were more pronounced in vertical facial dimensions and facial proportions than in transverse facial width. These findings expand population-specific anthropometric evidence and support the usefulness of direct craniofacial anthropometry for characterizing the facial phenotype of Down syndrome among Nigerian individuals.