Craniofacial Anthropometry and Single Nucleotide Polymophysm as Differential Identification Tools for Idomas and Igedes Population of Benue State

Abstract

Background: Craniofacial characteristics vary significantly across human populations due to genetic and environmental influences. Although such variations have been widely studied globally, there is limited data on African populations. This study aimed to investigate craniofacial genetics as a tool for differential identification among the Idoma and Igede ethnic groups in Nigeria. Specifically, the study sought to: (i) calculate craniofacial indices from facial image measurements; (ii) identify single nucleotide polymorphisms (SNPs) in the PAX3 and BMP4 genes associated with facial morphology; and (iii) evaluate the relationship between these genetic variations and observable craniofacial traits. Methods:This study was conducted in two phases. The first phase involved an anthropometric survey of 3,000 randomly selected participants aged 15–30 years. Sample size was determined using Fisher’s formula for large populations (N = Z²Pq/d²). Demographic data were collected using semi-structured questionnaires. Standardized facial photographs were analyzed using Digimizer software to obtain measurements including facial height, bizygomatic width, nasal dimensions, intercanthal distance, and ear size. Data were analyzed using IBM SPSS version 23.0 at a 95% confidence interval. The second phase involved molecular analysis. DNA samples were collected via buccal swabs. Target regions of the PAX3 and BMP4 genes were amplified using polymerase chain reaction (PCR), followed by purification and sequencing. Sequences were compared with reference data from the NCBI human genome database. Results: Facial indices were 88.45 ± 4.72 (Idoma males) and 87.81 ± 4.55 (Igede males), and 85.67 ± 4.28 (Idoma females) and 86.12 ± 4.41 (Igede females). Nasal indices ranged from 92.34 ± 6.85 to 95.67 ± 6.78 across both groups. Canthal indices ranged from 37.45 ± 2.65 to 38.56 ± 2.72, while ear indices ranged from 55.98 ± 3.69 to 57.23 ± 3.94. Very long facial types predominated in both populations. Broad and flat nasal types were most common, while intermediate eye types (canthal index 37–46) and large ear sizes were predominant across sexes. Genetic analysis identified 34 nucleotide substitution mutations in the PAX3 gene and 22 in the BMP4 gene. Individuals carrying these mutations exhibited distinct craniofacial measurement patterns compared to the general population. Conclusion: The integration of craniofacial morphometric analysis with genetic profiling provides a valuable and reliable approach for forensic identification among Idoma and Igede populations. Incorporating genetic markers such as PAX3 and BMP4 into forensic protocols may enhance the identification of both living individuals and human remains.