Hereditary disorders/abnormalities in this scenario are relational in nature since they are systematically passed from one generation to another in a pattern. It is most apparent that the disorders/abnormalities that are transmitted from parental forms to the subsequent filial generations of pedigree are similar in nature. In cases where the disease exists in all the six generations, both parents seem to carry alleles for the disease in their genotypic makeup which they later pass on to their offspring through genes. Nonetheless, the disease only manifest when two recessive alleles come to be in a pedigree an implication that a member can be a carrier without showing any symptoms of the disease (recessive alleles).
Taking correlation between sex of the pedigree carriers and occurrence of disease or lack of it into consideration, it comes out strongly that whenever the affected males are crossed with the unaffected females all the female offspring turn to be carriers while all males are unaffected. Most notably, no transmission of the alleles was recorded from male to male pedigree. This is an attestation that there is a positive correlation between phenotypic expression of the involved alleles and the chromosomal sex of the pedigree (Khalid & Kahl 2010). Nevertheless, only the male pedigrees are affected by the disease but not the female carriers.
With the full knowledge of Sex-Linkage, the X-Linked recessive alleles could only be transmitted through female carriers due to the presence of homozygous chromosomes (represented by XX) (Khalid & Kahl 2010). The recessive male carrier, on the other hand, could not transmit the alleles because they have heterozygous chromosomes (XY) of which the Y-chromosomes only determines the sex of its carrier organism. For this reason, environmental factors cannot influence the pattern of inheritance because autosomal chromosomes are not involved.
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