Construct a genetic diagram for a monohybrid cross to demonstrate how two parents without hereditary haemochromatosis can have a child with the disease. Use the following symbols: $H$ = normal $HFE$ allele; $h$ = mutant $HFE$ allele.
Some scientists think that the C282Y mutation may have originated in Ireland. Scientists sequenced DNA taken from two human fossil skeletons in Ireland. One fossil was 5200 years old and the other was 4000 years old. The scientists concluded that: • the human living 4000 years ago did have the C282Y mutation; • the human living 5200 years ago did not have the C282Y mutation. Explain how the results of these DNA sequencing studies could have been analysed so that the scientists could reach these conclusions.
Suggest how the C282Y allele of the $HFE$ gene has persisted in European populations.
Suggest explanations for why the percentage of people in different European countries who have one C282Y allele of the $HFE$ gene differs, as shown in Fig. 4.1.
Suggest one explanation for the differences between the three databases shown in Table 4.1.
In a population of 2501 people, 9 were homozygous recessive for the $HFE$ gene. Use equation 1 and equation 2 of the Hardy-Weinberg principle to work out how many people in the population are heterozygous for the $HFE$ gene. Equation 1: $p + q = 1$. Equation 2: $p^2 + 2pq + q^2 = 1$.