Genetics MCQs

A 6-month-old baby presents with failure to thrive, hepatosplenomegaly, and a cherry-red macula. Which enzyme deficiency is most likely responsible?

A patient with a suspected genetic disorder undergoes FISH analysis, which reveals a microdeletion on chromosome 7. Which condition is most likely?

A 2-year-old girl has intellectual disability, a high-pitched cry, and microcephaly. Which chromosomal abnormality is most likely?

A 25-year-old woman with mitochondrial myopathy is concerned about passing it on to her children. What is the mode of inheritance?

A newborn boy has ambiguous genitalia. Karyotype analysis shows 46, XX. What is the most likely cause?

A newborn is diagnosed with cystic fibrosis. What is the most common mutation responsible for this condition?

A 12-year-old boy with progressive muscle weakness has elevated creatine kinase (CK) levels. His younger brother is also affected. What is the most likely diagnosis?

A 32-year-old woman is found to have a BRCA1 mutation. What is her approximate lifetime risk of developing breast cancer?

A 5-year-old boy is diagnosed with Duchenne muscular dystrophy. Which of the following genetic mechanisms is responsible for this condition?

Which of the following chromosomal abnormalities is most commonly associated with Klinefelter syndrome?

A 10-year-old girl has Prader-Willi syndrome. Which genetic mechanism is responsible for this condition?

A newborn is diagnosed with trisomy 21 (Down syndrome). Which of the following is the most common cause of this condition?

A 6-year-old boy presents with sun sensitivity and an increased risk of skin cancer. He has a defect in nucleotide excision repair. What is the most likely diagnosis?

A man with hemophilia A has children. Which of the following statements about inheritance is correct?

A 4-year-old girl is diagnosed with achondroplasia. What is the most common genetic cause?

Which genetic disorder is caused by nondisjunction during meiosis?

Which of the following diseases follows an autosomal dominant inheritance pattern?

A 28-year-old woman with Turner syndrome (45, X) wishes to conceive. What is the most likely cause of her infertility?

A 6-month-old infant presents with progressive hypotonia, poor feeding, and exaggerated startle reflexes. Fundoscopy shows a cherry-red macula. Which of the following is the mode of inheritance?

A neonate presents with cleft palate, congenital heart defects, and hypocalcemia. Fluorescent in situ hybridization (FISH) confirms a 22q11.2 deletion. What is the most likely diagnosis?

A newborn has polydactyly, cleft lip, and severe intellectual disability. Genetic testing confirms trisomy 13. What is the most likely diagnosis?

A 35-year-old woman presents with progressive chorea, depression, and cognitive decline. What is the underlying genetic mechanism of her disease?

A 40-year-old man presents with progressive dementia and involuntary movements. His father also had similar symptoms in his 50s. Genetic testing confirms a trinucleotide repeat disorder. Which of the following mechanisms best explains the worsening of symptoms in each generation?

A 30-year-old woman with Leber hereditary optic neuropathy (LHON) asks if her children will inherit the disease. Which of the following is true?

A couple undergoes genetic counseling because they are both carriers of sickle cell disease. What is the probability that their child will inherit the disease?

A 7-year-old boy is diagnosed with Marfan syndrome. Which of the following best describes the inheritance pattern?

A newborn presents with hypotonia, feeding difficulties, and a weak cry. Genetic testing reveals a paternal deletion of chromosome 15q11-q13. What is the most likely diagnosis?

A 28-year-old woman with a history of multiple spontaneous abortions is found to have a balanced Robertsonian translocation involving chromosomes 14 and 21. What condition is most likely in a child she conceives?

A 4-year-old boy with mental retardation, inappropriate laughter, and ataxia is diagnosed with Angelman syndrome. What is the underlying genetic defect?

A 16-year-old girl with Fragile X syndrome is evaluated. Which of the following genetic mechanisms explains her condition?