Question

Some XP patients in rare cases also have Cockayne syndrome symptoms. This happens in people who have specific mutations in a particular gene. What gene is affected when this happens?

a. XPA gene
b. XPB gene
c. XPD gene
d. XPX gene
e. CSA gene

Answer 1

Individuals with mutations in the XPD gene can exhibit both Xeroderma Pigmentosum (XP) and Cockayne syndrome symptoms due to impaired DNA repair mechanisms, leading to an increased risk of skin cancer and developmental issues.

Step-by-step explanation:

Some XP patients in rare cases also have Cockayne syndrome symptoms due to specific mutations. When this occurs, it is usually because of mutations in the XPD gene. Xeroderma Pigmentosum (XP) patients are more prone to cancer because they cannot employ the nucleotide excision repair mechanism, leading to a higher risk of skin cancer after UV light exposure.

The presence of thymine dimers or adenine dimers, which are formed due to UV radiation, distorts the structure of DNA, and the inability to repair these dimers contributes to the increased cancer risk. Consequently, individuals with mutations in the XPD gene not only have difficulties with DNA repair, increasing cancer risk, but may also exhibit symptoms of Cockayne syndrome, which can include growth and developmental delays, photosensitivity, and neurological impairments.