Craniofacial Morphological PARAMETERS - Growth Hormone Receptor Gene Variant

Objective: To evaluate the relation of “Growth Hormone Receptor (GHR) gene variant P561T” and various craniofacial morphological parameters using “Polymerase chain reaction (PCR)” test.

Methods: The sample had 45 subjects who were selected randomly irrespective of the type of malocclusion. Blood samples (1.5ml) and lateral cephalograms were obtained from them with informed consent.

With the use of genomic DNA extracted from whole blood, the “GHR gene P561T” variant was detected by the “PCR – restriction fragment length polymorphism” method with the restriction enzyme Stu1.

To assess pattern of craniofacial morphology, four linear parameters were used on the lateral cephalograms: anterior cranial base length, maxillary length, mandibular ramus length and mandibular corpus length. The actual values were compared to the normal values as per the Schwartz analysis. Tests of significance were used for statistical assessment.

Results: Among the 45 subjects, 34 subjects had the restriction site for Stu1indicating the absence of “P561T variant”. These subjects had an increased mandibular ramus length (Actual value: 61.72±3.95 mm) when compared to normal (Normal Value: 54.07±3.06 mm).

11 subjects did not have specific restriction for Stu1 and presence of “P561T variant”.

Conclusions: This study indicates that subjects without P561T variant had a significantly greater mandibular height (p<0.0001). This suggests that the “Growth Hormone Receptor gene variant P561T” may be associated with mandibular height and could be considered as one of the genetic markers.