A genetic counselor sees a family for the first time for genetic assessment. The 24-year-old businessman and his 19-year-old sister are concerned about having a mutant allele and have decided to get tested. Their grandfather and great aunt both have Huntington’s disease which became apparent when they turned 52. Their father who is 47 years old appears healthy. The geneticist discusses both the benefits and risks of getting tested and orders some tests. Which of the following tests would best provide evidence for whether the siblings are carriers or not?
AGel electrophoresis
BRestriction enzyme digestion products
CPolymerase chain reaction
DPyrosequencing
EDNA isolation and purification
A 12-year-old boy develops muscle weakness and pain, vomiting, seizures, and severe headache. Additionally, he presents with hemiparesis on one side of the body. A muscle biopsy shows 'ragged red fibers'. What is true about the mode of inheritance of the disease described?
ASkips generations
BCommonly more severe in males
CIt can be transmitted through both parents.
DIt is transmitted only through the mother.
EMothers transmit to 50% of daughters and sons
A 32-year-old woman comes to the physician for genetic consultation. She has a history of recurrent generalized seizures, diffuse muscular weakness, and multiple episodes of transient left-sided paresis. She has been hospitalized several times for severe lactic acidosis requiring intravenous fluid hydration. Her 10-year-old daughter also has seizures and muscle weakness. Her 7-year-old son has occasional muscle weakness and headaches but has never had a seizure. Pathologic examination of a biopsy specimen from the woman's soleus muscle shows ragged-appearing muscle fibers. Genetic analysis of the patient's son is most likely to show which of the following?
AMutation in DNA repair gene
BGenetically distinct cell lines
CSilenced paternal gene copy
DHeterogenous mitochondrial DNA
EAltered allele on the X chromosome
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