Suppose a novel disease has been studied in several families

Suppose a novel disease has been studied in several families and is known to be caused by a mutation in one gene. The table below shows families where the disease is present. The four rightmost columns are the offspring of the father and mother listed in that row.

UPU K 322 Sp C fi www.sapl inglearning.com/ibiscms/mod/ibis/view.php?id 3176621 1/29/2017 55 PM A 51.4/100 Gradebook Print Calculator Periodic Table Question 13 of 21 Map Ca Sapling Learning macmillan learning Suppose a novel disease has been studied in several families and is known to be caused by a mutation in one gene. The table below shows families where the disease is present. The four rightmost columns are the offspring of the father and mother listed in that row. Select the most likely mode of inheritance of the disease. Normal Disease Family Father Mother Male Female Male Female O autosomal dominant Disease Normal 4 O X-linked recessive 2 Disease Normal 0 0 0 2 O X-linked dominant 3 Normal Disease 3 1 3 1 O autosomal recessive 4 Disease Normal 3 5 Normal Disease 0 I 1 6 Normal Disease 1 2 2 Select the description that best matches Select the description that best matches the female parent in family 6. the male parent in family 3. O has no disease alleles O has no disease alleles O has two disease alleles O has one disease allele O has one disease allele O has two disease alleles Ask me anything 7 P

Solution

a) X LINKED DOMINANT INHERITANCE

In this condition a female inherits one normal copy and one defective copy of the gene, the defective gene will be enough to cause the condition. If a male inherits a changed X chromosome then this would be enough to cause the disease because males only have one X chromosome. An affected female has a 50% (1 in 2) chance of having affected children (sons and daughters). An affected male will have all daughters affected but all sons will be unaffected.

The male parent in family 3 has no disease alleles

The female parent in family6 got one disease allele