PATHOLOGY

Detailed explanation-1: -Since this is a recessive disorder, one XH allele will give a normal phenotype. When the offspring do not have a XH and only have the Xh allele/alleles they will have the hemophilia condition. Man’s genotype is XhY.

Detailed explanation-2: -Hemophilia is a sex-linked recessive disorder. The abnormal gene responsible for hemophilia is carried on the X chromosome. Males have one X chromosome and one Y chromosome.

Detailed explanation-3: -This means that males only have one allele for factor VIII and one allele for factor IX. Thus, if a male has a hemophilia allele on his only X chromosome, he will have the disorder. A female inherits two copies of the factor VIII or factor IX gene, one from her mother and one from her father.

Detailed explanation-4: -A female with hemophilia would have to have her 2 sex chromosomes (the two X’s), or pair 23, with the hemophilia alleles. Those alleles cannot be the ‘normal’ or dominant allele (we’ll call it ‘H’).