A 4-year-old boy presents to his pediatrician for severe developmental delay. On exam he is noted to have macroorchidism, hypertelorism, large protruding ears, a large jaw, and a long thin face. Suspicious of what the diagnosis may be, the pediatrician orders a PCR and DNA sequencing. The results reveal an expansion of 250 repeats of CGG. What is the diagnosis of the boy?
AHuntington's disease
BSpinal and bulbar muscular atrophy
CMyotonic dystrophy type 1
DFragile X syndrome
EFriedreich ataxia
A 3-year-old is brought in to the pediatrician's office for a routine checkup. Her parents report that they noticed some regression in their daughter's behavior. She seemed to be progressing well during the first 18 months of her life. She had started saying words such as 'I', 'you' and 'mama' and she was linking words together. She also learned to follow simple instructions. However, over the past few months, they have noticed that she has been forgetting some of the things that she had previously learned and has had difficulty walking. On examination, the physician observes an apparently healthy girl who refuses to make eye contact and only slowly responds to her name. She is observed to wring her hands repeatedly in her lap. Which of the following genetic patterns of inheritance is responsible for this behavioral regression?
AX-linked dominant
BAutosomal dominant
CChromosomal trisomy
DX-linked recessive
EAutosomal recessive
A 5-year-old boy is brought to the clinic by his mother for an annual check-up. The family recently moved from Nebraska and is hoping to establish care. The patient is home schooled and mom is concerned about her son’s development. He is only able to say 2 to 3 word sentences and has been “behind on his alphabet." He always seems to be disinterested and "just seems to be behind.” The patient is observed to be focused on playing with his cars during the interview. Physical examination demonstrate a well-nourished child with poor eye contact, a prominent jaw, a single palmar crease, and bilaterally enlarged testicles. What is the most likely mechanism of this patient’s findings?
ACGG trinucleotide repeat expansion
BMicrodeletion of the long arm of chromosome 7
CMeiotic nondisjunction of chromosome 21
DCTG trinucleotide repeat expansion
EMicrodeletion of the short arm of chromosome 5
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