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Neurosensory and Neuromuscular System - Neurology, Ophthalmology, Otolaryngology Part 2 (16 test)
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1. A 22-year-old Caucasian female with no family history of color blindness (MIM*304000) marries a color-blind What is the risk for this couple of having a son or daughter who is color-blind?
- Virtually 0
2. A family presents with an unusual type of foot-drop and lower leg atrophy that is unfamiliar to their physician. The pedigree below is Based on the pedigree, what is the risk of individual III-3 having an affected child?
- Virtually 0
3. A 3-year-old Caucasian boy is evaluated by an ophthalmologist and is found to have retinitis pigmentosa, a disorder characterized by pigmentary granules in the retina and progressive vision loss. The pedigree below is obtained and the family comes in for What is the risk for individual II-2 of having an affected child if he impregnates an unrelated female?
- Virtually 0
4. A 6-month-old Caucasian boy of Ashkenazi Jewish origin plateaus in his development, exhibits a “startle” response to hand-claps, and is noted to have a central red area in his retina surrounded by white (cherry red spot). His physician suspects autosomal recessive Tay-Sachs disease (MIM*272800) and initiates evaluation that demonstrates deficiency of the lysosomal enzyme hexaminidase This deficiency leads to accumulation of complex glycolipids in brain and produces a ring of white, lipid-infiltrated cells around normal central retina (the macula). What is the risk that the grandmother of an affected child is a carrier (heterozygote) for Tay- Sachs disease?
- Virtually 0
5. A 1-month-old Caucasian male infant is being considered for adoption, and his older half sister is known to have developed hydrocephalus, an accumulation of cerebrospinal fluid in the brain Hydrocephalus is a multifactorial disorder, and the prospective parents wish to know the chance the boy will develop hydrocephalus. In order to estimate this risk, the physician must determine what proportion of genes the brother and the half sister have in common. What is this proportion?
- ¼ d.
6. A 66-year-old African American female is diagnosed with Parkinson disease (PD-MIM*168601) and there are no other cases in her family. She requests genetic counseling and/or testing to assess risks that her middleaged children will develop Her physician explains that 1% of people over 50 may contract the disease, that rare families exhibit autosomal dominant inheritance, and that usual risks are increased three-to fourfold for first-degree relatives of affected individuals. Based on this information, which of the following options provide appropriate genetic counseling for this patient?
- Likely multifactorial determination in your family with a 3% to 4% risk for your middle-aged children to develop PD
- Likely multifactorial determination in your family with a 1% risk for your middle-aged children to develop PD
- Likely autosomal dominant inheritance in your family with a 50% risk for your middle-aged children to develop PD
- Likely autosomal dominant inheritance in your family with a 25% risk for your middle-aged children to develop PD
- Likely multifactorial determination in your family with a 10% risk for your middle-aged children to develop PD
7. In the operating room, a 5-year-old Hispanic boy receives succinylcholine as a muscle relaxant to facilitate intubation and anesthesia. The operation proceeds until it is time for recovery, when the child does not begin A hurried discussion with the father discloses no additional problems in the family, but he does say that he and his wife are first cousins. Which of the following is the most likely possibility?
- An autosomal dominant disorder that interferes with succinylcholine metabolism
- An autosomal recessive disorder that interferes with succinylcholine metabolism
- An X-linked disorder that interferes with succinylcholine metabolism
- A lethal gene transmitted through consanguinity that affects the respiratory system
- Mismanagement of halothane anesthesia during the operation
8. Pharmacogenetics, or the study of drug-induced disease due to genetic variation, is receiving increased attention particularly with regard to population or at least preoperative The frequency of heterozygotes for variant butyrylcholinesterase (BChE) alleles in Caucasians is about 4 per 100, implying an incidence of individuals with potential for severe apnea of which of the following?
- 1 in 5000
- 1 in 2500
- 1 in 1250
- 1 in 500
- 1 in 50
9. A 6-month-old Caucasian girl of Ashkenazi Jewish background seems to plateau in development after a normal gestation, delivery, and early She rolled over well with smiling and good interaction but became less active and does not maintain a sit. Her pediatrician notes low muscle tone and claps her hands to elicit an exaggerated extension of her arms (Moro reflex—enhanced startle response). Ophthalmologic examination reveals a central red area of the retina surrounded by white tissue (cherry red spot). A diagnosis of lipid storage disease (neurolipidosis) is suspected. If the diagnosis is correct, what is the risk that the next child of these parents will be affected with the same disease?
10. The cause of Tay-Sachs disease (MIM*272800) is best described by which of the following?
- Excess of a lysosomal enzyme in blood due to defective uptake
- Deficiency of a lysosomal enzyme that digests proteoglycans
- Deficiency of a membrane receptor that takes up proteoglycans
- Deficiency of a mitochondrial enzyme that degrades glycogen
- Deficiency of a mitochondrial triglyceride lipase
11. The frequency of carriers of Tay-Sachs disease (MIM*272800) in Ashkenazi Jewish populations is 1 in Some Jewish communities offer carrier testing for young adults so they will know their status before marriage. A known carrier female becomes involved with an exchange student from Russia who also is Ashkenazi Jewish but who has not had carrier testing. What is the chance that a child of this union will have Tay-Sachs disease?
- 1 in 2 1/120
- 1 in 15 1/240
- 1 in 30 1/3600
- 1 in 60 1/9000
- 1 in 120 1/36,000
12. A couple decide to have prenatal diagnosis because their previous child has Tay-Sachs disease (MIM*272800). Which of the following prenatal diagnostic techniques is optimal for fetal diagnosis?
- Chorionic villus sampling (CVS)
- Percutaneous umbilical blood sampling
- Amniotic fluid α-fetoprotein levels
- Maternal serum α-fetoprotein (MSAFP)
- Fetal x-rays
13. A 2-year-old child is hospitalized for evaluation of poor growth and low muscle tone. The most striking physical finding is unruly, “kinky” hair, but the child also has increased joint laxity and thin skin. Which of the following laboratory findings is most likely?
- High ceruloplasmin
- High tissue copper
- Low serum iron
- Low saturation of transferrin
- Low serum haptoglobin
14. A male child presents with delayed development and scarring of his lips and hands. His parents have restrained him because he obsessively chews on his lips and Which of the following is likely to occur in this child?
- Increased levels of 5-phosphoribosyl-1-pyrophosphate (PRPP)
- Decreased purine synthesis
- Decreased levels of uric acid
- Increased levels of hypoxanthine-guanosine phosphoribosyl transferase (HGPRT)
- Glycogen storage
15. The figure below shows a pedigree that includes individuals with Charcot-Marie-Tooth disease (CMT), a neurologic disorder that produces dysfunction of the distal extremities with characteristic If individual III-4 becomes pregnant, what is her risk of having a child with CMT?
- ¼ 1/8
- Virtually 0
16. A child with severe epilepsy, autistic behavior, and developmental delay has characteristics of a condition known as Angelman syndrome (MIM*105830). Because of the syndromic nature of the disorder and the developmental delay, a karyotype is performed that shows a missing band on one chromosome Which of the following best describes this abnormality?
- Interstitial deletion of 15
- Terminal deletion of 15
- Pericentric inversion of 15
- Paracentric inversion of 15