The Fugate family, living in a rather isolated territory near Troublesome Creek in Kentucky, was characterized by having family members with blue skin. To understand the causes of the condition, it is important to set hypotheses and examine the medical history of the family’s generations.
Hypothesis on Why These People Were Blue
The first hypothesis to explain the condition is the following one: If the family members have a specific blood condition or mutation of a gene, the color of their skin could become blue. The second hypothesis is the following one: If the family members were exposed to some environmental causes such as chemicals, water, food pollutants, or radiation, the color of their skin could become blue. In order to prove or disprove these two hypotheses, it is necessary to conduct certain blood tests and, in addition, to test the water, soil, and air conditions in the region to find chemicals or other pollutants.
The Fugate Family Tree
While focusing on the family tree, it is possible to state that the “blueness” of the family members is a heritable trait because there is a rather predictable pattern of appearing “blueness” in children across generations because of genetic variations in parents (see Figure 1).
In order to state that the observed pattern is a dominant/recessive inheritance, it is necessary to assume that Elizabeth was heterozygous in her gene pattern, and John could not be homozygous. There are still questions regarding the gene pattern of the woman from the Ritchie clan (see Figure 1).
While focusing on the allele designations proposed for family members, it is possible to state that in this case, parents need to carry a normal gene and a recessive gene, and their children can be affected or not affected according to the Mendelian pattern (see Figure 1).
Thus, the members of the Fugate family seem to suffer from methemoglobinemia, a blood inherited condition when people have high levels of methemoglobin in their blood and their blood cells cannot bind oxygen.
The lines of the graph in the case study provide the information that being heterozygotes, parents are set between two phenotypes that can be discussed as homozygous, normal, or blue. In this case, it is reasonable to focus on the enzyme activity in different phenotypes. Thus, specific genotype designations will be bb, Bb, and BB for the lines on the graph. As a result, it is possible to speak about incomplete dominance as the possible pattern of inheritance in this case.
Conclusions for various parts of the case study seem to be different, but the problem is in the fact that both patterns of inheritance can work because different perspectives for the analysis are selected. The Mendelian inheritance pattern can be discussed with references to both perspectives, and they are correct, depending on the selected criterion which can be the colour of the skin in generations or the enzyme activity, as it is represented in the graph in the case study.