Morphogenetic variability and genetic loads among patients with different expression of developmental hip dysplasia

Abstract

Assuming that developmental hip dysplasia (DDH) is a genetically controlled disease, we made a hypothesis that an increased homozygosity level and genetic loads, among the patients with DDH, could be some kind of predisposition for the degree of illness expression. Using HRC-test (test for determination of homozygously recessive characteristics in humans) we analyzed presence, distribution, and individual combination of 20 selected genetically controlled morphophysiological traits among DDH patients (N=200) and controls (N=200). Among groups of DDH patients the increase in the degree of genetic homozygosity correlates with the degree of illness expression (dysplasia/subluxations-39%; luxations-45%). There is significant difference in mean HRC value between tested groups of patients with dysplasia/luxations (p<0.05) and subluxations/luxations (p<0.05). Our results showed increase of morphogenetic homozygosity in the group of patients with bilateral hip dislocation (BL) (45%), compared to group with unilateral expression (UL) (41%) and control (23.5%). There is significant difference in mean HRC value between tested groups of patients with UL and BL (p<0.05). Also, surgically treated patients showed significant increase of genetic homozygosity (43%) compared to those conservatively treated (37%) and controls. We found significant difference in mean HRC value between tested groups of patients that were treated conservatively and surgically (p<0.05). Our results showed increase of genetic homozygosity in the groups of DDH female patients (44%), compared to male patients (39%), while in controls there was no difference between gender. Female DDH patients show a significant increase in average homozygosity of tested genetic markers (p<0.05) than male DDH patients. The enlargement of genetic loads correlates with severity of the disease (in studied groups of DDH patients) which may indicate some kind of predisposition for the degree of illness expression.