Question

Jack and Jill's son Jake has a severe case of myclonic epilepsy and ragged-red fiber (MERRF) syndrome. His case includes frequent and disabling myclonic seizures (involuntary twitching of the muscles) along with hearing loss, exercise intolerance, and poor night vision. Like most cases of MERRF, his case is associated with a mitochondrial mutation that he inherited from his mother Jill. His mother doesn't know that she harbors the MERRF mutation among her mtDNA molecules, but she has experienced occasional mild muscle twitching throughout her life and she does not see very well at night. What is/are the MOST likely explanation(s) for the difference in the severity of MERRF between Jake and his mother

Answer 1

Answer:In most cases, people with MERRF inherit an altered mitochondrial gene from their mother, who may or may not show symptoms of the disorder. Less commonly, the disorder results from a new mutation in a mitochondrial gene and occurs in people with no family history of MERRF.

Explanation:MERRF is inherited in a mitochondrial pattern, which is also known as maternal inheritance. This pattern of inheritance applies to genes contained in mtDNA. Because egg cells, but not sperm cells, contribute mitochondria to the developing embryo, children can only inherit disorders resulting from mtDNA mutations from their mother. These disorders can appear in every generation of a family and can affect both males and females, but fathers do not pass traits associated with changes in mtDNA to their children.