A Morphometric Analysis of the Ear, Nose, and 2D:4D Digit Ratio in Individuals With Down Syndrome

Down syndrome (DS) is the most common chromosomal disorder worldwide, characterized by congenital anomalies, distinctive facial morphology, and developmental delays. Although phenotypic features vary, many individuals with DS exhibit consistent craniofacial traits. In this study, we evaluated the morphometric characteristics of the ears, nose, and the second-to-fourth digit ratio (2D:4D) in children with DS, and examined their relationship with age, sex, and lateralization. The sample included 40 children with DS (20 girls and 20 boys), aged 2 to 13 years, attending rehabilitation centers in Konya. Anthropometric and photogrammetric methods were used to measure nasal width, length, height, alare-pronasale and alare-subnasale distances, nasal root width, nasofrontal angle, and nasal tip angle. Ear dimensions, including width, length, earlobe size, and concha measurements, were recorded. The 2D:4D digit ratio was also calculated. Statistical analyses revealed that the 2D:4D ratio differed significantly between sexes (P < 0.05), while no significant lateral differences were observed. All parameters were positively correlated with age. These findings contribute to the understanding of craniofacial development in DS and may inform clinical applications such as early diagnosis, genetic counseling, surgical planning, and the customization of assistive devices like glasses and hearing aids.