This paper includes 10,000 individuals from the population of the Municipality of Preserve, which is located in the E-75 corridor in southeastern Serbia on the border with northern Macedonia. During the physical interviews in the families we encountered some genetic diseases where we singled out type A hemophilia. During the direct observation, we found that only males were infected with this disease while females were not affected with this type of hemophilia. Also based on biochemical, molecular analyzes we noticed that all cases with hemophilia were with blood group A and with rhesus factor negative. Also based on the statements of the scientist Bar that one X chromosome in the early embryonic stages becomes inactive, then women must also be affected by this disease. These two cases of negative R-factor in all hemophiliacs led us to another study about the type of inheritance and their possible correlation. Analyzing the genetic trees we did not have cases of females being hemophilic and the other phenomenon was why these hemophiliacs have group A negative. This gives us an idea that antigen A is not related to blood coagulation factor (enzyme). This leads us to think that the possibility of men having hemophilia may be related to a lack of antigen A. The alleles for blood groups are known to be on chromosome 9 while the alleles for the rhesus factor are on chromosome 1. Negative blood group A and clotting factor VIII are Missense mutations (Ala723Thr and Lys439Ser) and protein shortening changes (Trp1854 * and Arg2326 *) have been observed in 2 each of these cases. Of the 3 hemophiliac cases having incompatible antigen-activity ratios, most of those mutations produced FVIII with low specific activity for FVIII and for antigen A with rhesus negative blood factor. Regarding the body of Bari from many genealogical, biochemical analyzes we came to the conclusion that this body of Bari is genetically active, but morphologically changes its original shape. From biochemical analysis and knowing that the egg cell is approximately 10000 times larger than the sermatozoid made us analyze the biochemical structure of the egg cell. In the egg cell it was observed that inside the cytoplasm is rich in numerous enzymes which at the time of fertilization will promote the division of the zygote into two new cells. In this case we found out that the cause of condensation of X chromosome DNA in sperm is the factor of the egg cell environment. This means that enzymes, mitochondrial DNA have many redox enzymes that can affect the condensation of the X chromosome coming from the father. Assuming that the sex X chromosome is inactive we did not have the opportunity for women to be hemophilic as well. By doing the genealogical analysis of these families we will present the thoughts about the role of Bar's body when it comes to hemophilia type A. For these cases of hemophiliacs laboratory, biochemical and genetic analyzes have been done to observe the level of penetration and expressiveness of factor VIII. We will present through the genetic tree the origin or genealogy of the gene for this disease. Based on biochemical and genetic analysis using PCR, we will present the level of factor I, IX, XI, aTTP, vWF- Von Willebrandov factor, locus Xq28, genotype ccddee, fibrinogen, blood group, rhesus factor in hemophiliacs included in this study