Role of the rs6184 growth hormone receptor gene polymorphism in mandibular morphogenesis

Polymorphisms in the growth hormone receptor (GHR) gene influence the craniofacial system by affecting the growth of the mandibular body length and ramal height, with significant variations observed across different ethnic populations. This study investigated the relationship between a single nucleotide polymorphism (rs6184) in the GHR gene and its effects on mandibular morphogenesis in a Dravidian population.

A total of 250 subjects were divided into three groups. Group 1 included 100 subjects with skeletal Class I malocclusion and average ramal height (control group). Group 2 included 150 patients with skeletal Class II malocclusions and reduced mandibular body length. On the basis of ramal height, group 2 was divided into two groups with 75 subjects each (short ramus: group 2a) and (long ramus: group 2b). DNA extracted from the salivary samples of individuals was analyzed to identify the genotype of the rs6184 using the polymerase chain reaction-restriction fragment length polymorphism method and compare it in the three groups.

The genotype and allele frequencies showed statistically significant differences between the control (group 1) and groups 2a and 2b (P < 0.0001), with the polymorphic homozygous TT genotype found only in subjects with Class II malocclusions and reduced mandibular body length. However, no statistically significant difference was found between individuals with small and long ramal heights (group 2a and 2b, P = 0.7789).

The rs6184 polymorphic variant of the GHR gene can be considered a candidate gene for mandibular morphogenesis in the Dravidian population.