*3.2.4 The relationship of genotypes of LRP5rs121908669 with femoral bone mineral density*

The results of the odd ratio test, chi-square test, and McNemar test are shown in **Table 4**. These applications were applied to study the relationship between the genotypes of LRP5rs121908669 and femoral bone mineral density.

The appearance of low femoral bone mineral density (osteopenia, osteoporosis) increases and normal femoral bone mineral density decreases in carriers of the CC genotype. The appearance of normal femoral bone mineral density increases and the appearance of low femoral bone mineral density (osteopenia) decreases in carriers of the GG genotype. The appearance of low lumbar bone mineral density (osteopenia, osteoporosis) increases among carriers of the GC genotype.

It is noted that the genotypes of the mutation have effects on the bone mineral density in the femoral region and with a stronger effect than their effect on the bone mineral density in the lumbar region.

It can be explained that the LRP5rs121908669 mutation is one of the mutations of the LRP5 gene that encodes the LRP5 protein which is a part of the WNT pathway. WNT pathway is one of the most important pathways involved in the formation of cortical bone [19]. The cortical bone makes up the majority of the femur bone. Thus, the emergence of the greater effect of the genotypes of LRP5rs121908669 can be explained in the femur than in the lumbar bone, since the lumbar bone is formed mostly from spongy bone [1]. For more clarification, each of the femur and the lumbar bone consists of cortical bone and cancellous bone, but the proportion of cortical bone predominates in the femur, and the proportion of cancellous bone predominates in the lumbar bone [1].

This study is the first of its kind in the world. There is only one Belgian study that revealed this mutation by chance and it was not studied afterward, but in that study it was associated with an increase in bone mineral density without specifying the


#### **Table 4.**

*Results of the statistical relationships that study the relationship between femur T-score values and genotypes of LRP5rs121908669.*

genotype, and this is contrary to the results of this research. However, it seems that it will receive wide attention after it was added to the lists of genetic laboratory kits for one of the major American international companies to manufacture laboratory kits for genetic analysis in 2022.
