[MCQs] Genetic Medicine: Clinical Genetics and Inborn Errors of Metabolism Quiz - Part 2 (13 test)

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Question 1

A standard karyotypic analysis is ordered for a girl with heart defects, developmental delay, and an unusual appearance. The results are normal, but a colleague suggests the diagnosis of DiGeorge-velocardiofacial spectrum and recommends a FISH test with results shown in the figure below. A control probe highlights the chromosomes 22s in the metaphase spread and the test probe gives a signal on one of the chromosomes 22. Which of the following statements best summarizes this result?

A	The initial karyotype results are inconsistent with the FISH results.
B	This is a normal result, making the diagnosis of DiGeorge-velocardiofacial syndrome less likely.
C	A small deletion is present on one of the patient’s number 22 chromosomes, confirming the suspected diagnosis.
D	The FISH test was not useful, since the initial karyotype results were normal.
E	The chromosome with the positive signal is paternal in origin.

Question 1 Explanation:

Fluorescent in situ hybridization (FISH) analysis is a technique in which molecular probes that are specific for individual chromosomes or chromosomal regions are used to identify the presence and dosage of these regions. FISH probes identify submicroscopic microduplications microdeletions that cannot be detected by routine chromosome analysis. In this FISH result, the controle probes identify both chromosomes 22, but the test probe gives a signal on only one, indicating the presence of a chromosome 22 microdeletion and confirming the suspected diagnosis of DiGeorgevelocardiofacial spectrum (MIM*192430). Parental origin of the deleted chromosome cannot be determined by this result. The newer high resolution microarray an alysis technique can be visualized as placing 100,000 to a million FISH probes on the chromosomes, comparing control and patient hybridization to detect microduplication/deletion anywhere in the genome. (Figure provided by Dr. Vijay Tonk of Texas Tech University).

Question 2

A female who is at risk to be a carrier of hemophilia A desires prenatal diagnosis. She does not want her extended family to know about her pregnancy if the fetus is affected. Which of the following prenatal diagnostic techniques should be advised?

A	Amniocentesis with western blot analysis of factor VIII
B	Chorionic villus sampling with DNA analysis for factor VIII mutations
C	Percutaneous umbilical blood sampling with testing of factor VIII levels
D	Amniocentesis with DNA analysis for factor VIII mutations
E	Chorionic villus sampling with assay of factor VIII activity

Question 2 Explanation:

Chorionic villus sampling (CVS) is performed at 10 to 12 weeks’ gestation, before a female is obviously pregnant. This technique preserves the confidentiality of prenatal decisions because diagnostic results are available by 12 to 14 weeks’ ge station rather than the 18 to 20 weeks for standard amniocentesis. DNA analysis must be employed because factor VIII is not expressed in chorion or amniotic cells. Percutaneous umbilical blood sampling (PUBS) must be performed later in gestation (>18 weeks). Because some factor VIII gene mutations may give normal amounts of structurally abnormal factor VIII, activity rather than amounts of factor VIII protein must be measured for diagnosis.

Question 3

A 4-year-old African American girl presents with Prader-Willi syndrome obesity, short stature, hypogonadism, and mental disability. Despite a normal gestation and delivery, she had extremely low tone (hypotonia) in the newborn nursery and had to be tube-fed until age 6 months. At age 3 years, she began eating too much, taking food from her parents’ plates and even foraging in the garbage for food. Her physician suspects the diagnosis of Prader-Willi syndrome, and recalls that about 60% of Prader-Willi patients have a small deletion on the proximal long arm of chromosome 15. Which of the following techniques would be most accurate in testing for this deletion?

A	Standard karyotyping of peripheral blood leukocytes
B	Northern blotting of mRNAs transcribed from the deletion region
C	Restriction analysis to detect DNA fragments from the deletion region
D	Rapid karyotyping of bone marrow
E	Fluorescent in situ hybridization (FISH) analysis of peripheral blood lymphocytes using fluorescent DNA probes from the deleted region

Question 3 Explanation:

The Prader-Willi deletion is quite small and is not usually detected by standard metaphase karyotyping. Fluorescent in situ hybridization (FISH) is the most cost-effective and accurate method for detecting the deletion in Prader-Willi syndrome (incorrect answers a-d). Fluorescent DNA probes from the deletion region (chromosome band 15q11) will give two signals on the two chromosomes 15 in normal subjects, but only one signal in Prader-Willi patients with one normal and one deleted Chromosome 15. Detection of RNA or DNA fragments from this region would require quantitation to reveal one-half normal amounts, since genes on the homologous 15 chromosome would be normal (incorrect answer b). Standard karyotypes typically display about 300 bands over the 23 chromosomes or about 10 bands on chromosome 10. This is adequate for detecting aneuploidy but inadequate for small (submicroscopic) deletions seen in conditions such as Prader-Willi syndrome. Bone marrow samples could provide rapid karyotype results because marrow contains actively dividing cells, av oiding the delays for standard karyotyping because peripheral blood T leukocytes must be stimulated to divide using lectins such as phytohemagglutinin. Now a combination of DNA probes for the chromosomes involved in common trisomies (13, 18, 21, X, and Y) is used to evaluate chromosomes in white blood cell nuclei, gi ving results without the requirement of cell division (rapid FISH). Although the nuclear chromosomes are not clumped as they would be in metaphase of cell division, counting of the fluorescent signals for each chromosome provides a preliminary diagnosis (eg, three signals for chromosome 21 in a child with trisomy 21 or Down syndrome).

Question 4

A child is referred for evaluation because of low muscle tone and developmental delay. Shortly after delivery, the child was a poor feeder and had to be fed by tube. In the second year, the child began to eat voraciously and became obese. He has a slightly unusual face with almond-shaped eyes and downturned corners of the mouth. The hands, feet, and penis are small, and the scrotum is poorly formed. The diagnostic category and laboratory test to be considered for this child are which of the following?

A	Sequence, serum testosterone
B	Single birth defect, serum testosterone
C	Deformation, karyotype
D	Syndrome, karyotype
E	Disruption, karyotype

Question 4 Explanation:

This child has several minor anomalies, a major anomaly that affects the genitalia, and developmental delay. These multiple affected and embryologically unrelated body regions suggest a syndrome rather than a sequence. Because of the multiple anomalies and developmental delay, the first diagnostic test to be considered is a karyotype rather than a test for specific organ function, such as serum testosterone.

Question 5

A 14-year-old Caucasian adolescent has mild disability requiring resource classes and is obese because the parents have had great difficulty controlling her food intake at school and in her grandmother’s house where she goes after school. Her physician decides to test for Prader-Willi syndrome and knows that the paternal imprint on chromosome 15 is absent in this condition as opposed to the maternal imprint in Angelman syndrome. A fluorescent in situ hybridization (FISH) test for chromosome 15 deletion had been normal when developmental delay was first suspected, but the physician decides that the girl’s increased appetite may reflect uniparental disomy (two chromosome 15 from one parent) that has caused a milder form of Prader-Willi syndrome. Southern blotting is performed to determine the origin of the patient’s number 15 chromosomes. In the figure below, a hypothetical Southern blot with DNA probe D15S8 defines which of four restriction fragment length polymorphisms (RFLPs) are present in DNA from mother (M), child (C), and father (F). Which of the following accurately conveys the result of this test?

A	Biparental origin of chromosome 15, confirming a diagnosis of Prader-Willi syndrome
B	Origin of both chromosome 15 from father, suggesting a diagnosis of Angelman syndrome
C	Origin of both chromosomes from the mother, suggesting a diagnosis of Prader-Willi syndrome
D	Absence of a paternal chromosome 15, diagnosing nonpaternity and excluding a diagnosis of Prader-Willi syndrome
E	Indeterminate result because the D15S8 locus is deleted in the child

Question 5 Explanation:

Because both parents are heterozygous for the D15S8 locus (mother with alleles 1 and 2, father with alleles 3 and 4) as distinguished by different migration (different sizes) during gel electrophoresis, the child (C) has only the maternal alleles 1 and 2 and must have received both of the mother’s chromosomes 15 (answers a, b, and e incorrect; nonpaternity possible as in answer d, but less probable in this context). Angelman syndrome with seizures, severe mental disability, and a normal appetite is quite different from Prader-Willi syndrome with mild disability and insatiable appetite (never feel full). Patients with Angelman syndrome lack maternal imprinting of the chromosome 15q11 region, while those with Prader-Willi lack the paternal imprint. This deficiency can arise by deletion (60% in Prader-Willi, ∼5% of Angelman), origin of both chromosomes 15 from one parent (uniparental disomy), or failure of imprinting (the latter causes occur in ∼30% of Prader-Willi, but in the majority of Angelman patients). DNA methylation testing (maternal vs paternal imprinting is reflected by the pattern of 5-methyl-cytosines on DNA) is the most sensitive test for these disorders, revealing a maternal 15 imprinting pattern (deletion or absence of paternal chromosome 15 as in Prader-Willi), paternal 15 imprinting pattern (deletion or absence of maternal chromosome 15 as in Angelman), or both maternal and paternal 15 imprinting patterns (normal result).

Question 6

The figure in Question 5 demonstrates that the child is missing both paternal chromosome 15 alleles; nonpaternity is a more plausible explanation than uniparental disomy. The hypothetical Southern blot shown below illustrates a DNA “fingerprinting” analysis to examine paternity, where maternal (M), child (C), and paternal (F) DNA samples have been restricted, blotted, and hybridized simultaneously to the probes D7Z5 and D20Z1. The distributions of restriction fragment alleles suggest which of the following?

A	The child is adopted
B	False maternity (ie, baby switched in the nursery)
C	False paternity
D	Correct maternity and paternity
E	None of the above

Question 6 Explanation:

DNA fingerprinting is used in both paternity and forensic analyses and relies on highly variable DNA polymorphisms called variable numbers of tandem repeats (VNTRs). The multicopy repeats include (CA)n and minisatellite sequences that are present throughout the genome. The usual VNTR probe is directed against single-copy DNA that flanks these repeats and yields multiple restriction fragment sizes that reflect the number of intervening repeats. The hypothetical probes D7Z5 and D20Z1 shown in the question (figure below Question 297) recognize VNTR loci on chromosomes 7 and 20 that yield at least three alleles. Because the child’s two alleles for D7Z5 (and D20Z1) match those of the mother and father, correct maternity an d paternity are established with a degree of error equal to the chance that these allele combinations would occur in an unrelated individual. In practice, at least five VN TR probes are employed so that the odds for paternity (or nonpaternity) are very high indeed.

Question 7

An infant with severe muscle weakness is born to a mother with mild muscle weakness and myotonia (sustained muscle contractions manifested clinically by the inability to release a handshake). The mother’s father is even less affected, with some frontal baldness and cataracts. Worsening symptoms in affected individuals of successive generations suggest which of the following inheritance mechanisms?

A	Genomic imprinting
B	Heteroplasmy
C	Unstable trinucleotide repeats
D	Multifactorial inheritance
E	Mitochondrial inheritance

Question 7 Explanation:

Anticipation refers to the worsening of the symptoms of disease in succeeding generations. The famous ge neticist L. S. Penrose dismissed anticipation as an artifact, but the phenomenon has been validated by the discovery of expanding trinucleotide repeats. Steinert my otonic dystrophy is caused by unstable trinucleotide repeats near a muscle protein kinase gene on chromosome 19; the repeats are particularly unstable during fe male meiosis and may cause a severe syndrome of fetal muscle weakness and joint contractures. Variable expressivity could also be used to describe the family in the question, but the concept implies random variation in severity rather than progression with succeeding generations. Diseases that involve triplet repeat instability exhibit a bias for exaggerated repeat amplification during meiosis (eg, females with the fragile X syndrome or myotonic dystrophy and males with Huntington chorea). The explanation for this bias is unknown.

Question 8

Most isolated congenital anomalies exhibit which of the following?

A	Mendelian inheritance
B	Chromosomal inheritance
C	Multifactorial inheritance
D	Maternal inheritance
E	Atypical inheritance

Question 8 Explanation:

When present as an isolated anomaly, spina bifida (meningomyelocele) exhibits multifactorial inheritance. Chromosomal inheritance with imbalance of chromosome segments usually produces a pattern of multiple birth defects (a syndrome) with concurrent mental disability (incorrect answer b). Maternal inheritance refers to transmission from the mother as with mitochondrial DNA mutations (incorrect answer d). Atypical inheritance (incorrect answer e–genomic imprinting, trinucleotide repeat instability, mitochondrial inheritance) has not been implicated in neural tube defects.

Question 9

A newborn Caucasian girl has bilateral club feet (feet deviated inward and malformed) with minimal movement of her lower She has a midline bulge over her lower spine that by MRI shows absent vertebrae with extrusion of spinal cord tissue and surrounding dura as a subcutaneous cyst. The lesion is diagnosed as spina bifida occulta and is known to follow the usual multifactorial determination of spina bifida and other common birth defects. Spina bifida exhibits female predilection with an incidence of 1 in 1000 Caucasian individuals and recurrence risks of 3% for first-degree relatives and 0.5% for second-degree relatives. The risk can be decreased by two-thirds if mother takes folic acid before conception. What is the risk that the parent’s second child will have spina bifida if mother takes folic acid before becoming pregnant?

A	1 in 1000
B	3 in 1000
C	1 in 100
D	3 in 100
E	Less than 0.1%

Question 9 Explanation:

The parent’s next child will be related to the child with spina bifida as a first-degree relative (parentchild, siblings), having 50% of their genes in common. Sharing of these genes that are now shown to confer polygenic susceptibility to spina bifida (by birth of an affected child) means that the second child will have a much higher (3%) chance for spina bifida than the general 1 in 1000 risk in the Caucasian population. However, the polygenic component of multifactorial determination can be moderated by changing the environmental component; reducing the risk for spina bifida in the second child to 1% through preconception counsel and ensuring that the mother takes folic acid supplementation (incorrect answers a, b, d, and e). Second-degree relatives have 25% of their genes in common (parent-grandchild, aunt/uncle-niece/nephew). Risk for multifactorial disorders (diabetes, schizophrenia, most common diseases including isolated birth defects) drop off sharply with degrees of relationship as shown in the example of spina bifida. Had the child had a rare pattern of birth defects that includes spina bifida, then a Mendelian disorder could be possible and with recurrence risks as high as 25% from autosomal recessive inheritance.

Question 10

Neural tube defects, such as spina bifida and anencephaly, are best diagnosed by which of the following laboratory tests?

A	Chorionic villus biopsy and karyotype at 10 weeks after the last menstrual period (LMP)
B	Maternal serum α-fetoprotein (MSAFP) levels and ultrasound at 16 weeks after conception
C	Amniotic fluid α-fetoprotein (AFP) levels and ultrasound at 16 weeks after the LMP
D	Amniotic fluid acetylcholinesterase levels at 16 weeks after conception
E	Amniotic fluid karyotype and ultrasound at 16 weeks after the LMP

Question 10 Explanation:

Any defect of the fetal skin may elevate the amniotic α-fetoprotein (AFP) level, causing a parallel rise of this substance in the maternal blood. Neural tube defects such as anencephaly or spina bifida elevate the AFP in amniotic fluid or maternal serum; other causes of increased AFP include fetal kidney disease with leakage of fetal proteins into amniotic fluid. Mild forms of spina bifida or meningomyelocele may be covered by the skin so that the AFP is not elevated, and maternal serum AFP is less sensitive than amniotic fluid AFP for such cases. Ultrasound is required to detect covered neural tube defects that do not leak fetal AFP into the amniotic fluid and maternal blood. Acetylcholinesterase is an enzyme produced at high levels in neural tissue that is somewhat more specific than AFP for neural tube defects; it is used for confirmation rather than as a primary prenatal test. Chorionic villus biopsy is performed at ab out 10 weeks after the last menstrual period (LMP) and amniocentesis at 14 to 16 postmenstrual weeks. Because conception often occurs 2 weeks prior to the LMP, distinction between postconceptional and postmenstrual timing is important for early stages of pregnancy. Neural tube defects are usually localized, mu ltifactorial anomalies rather than part of a malformation syndrome that can result from chromosomal aberrations. For this reason, documentation of the fetal karyotype by chorionic villus biopsy or amniocentesis does not influence the risk for neural tube defects.

Question 11

A couple has a child who has been diagnosed with medium-chain acyl-coenzyme A (CoA) dehydrogenase deficiency (MCAD-MIM*201450), a condition that affects the body’s ability to metabolize medium-chain fatty acids. This couple is now expecting another child. What is the risk that this child will have MCAD?

A	2/3
B	1/2
C	1/3
D	1/4

Question 11 Explanation:

Metabolic disorders almost always involve enzyme deficiencies and are thus au tosomal or X-linked recessive inheritance. Assuming that nonpaternity or an unusual method of inheritance is not operative, the parents of a child with an autosomal recessive condition are obligate heterozygotes. Therefore, their risk of having a child with medium-chain acyl-coenzyme A (CoA) dehydrogenase deficiency (MCAD) is one-fourth or 25% for each future pregnancy.

Question 12

In the treatment of propionic acidemia, which of the following is contraindicated?

A	Antibiotics
B	A diet high in fatty acids
C	Caloric supplementation
D	Aggressive fluid and electrolyte management
E	Hemodialysis

Question 12 Explanation:

In treating inborn errors of metabolism that present acutely in the newborn period, aggressive fluid and electrolyte therapy and caloric supplementation are important to correct the imbalances caused by the disorder. Calories spare tissue breakdown that can increase toxic metabolites. Because many of the metabolites that build up in inborn errors of metabolism are toxic to the central nervous system, hemodialysis is recommended for any patient in stage II coma (poor muscle tone, few spontaneous movements, and responsive to painful stimuli) or worse. Dietary therapy should minimize substances that cannot be metabolized—in this case fatty acids, because the oxidation of branched-chain fatty acids results in propionate. Antibiotics are frequently useful because metabolically compromised children are more susceptible to infection.

Question 13

Which of the following is most likely in an untreated child with PKU?

A	Elevated tyrosine
B	Increased skin pigmentation
C	Decreased skin pigmentation
D	Normal phenylalanine hydroxylase levels
E	Elevated alanine

Question 13 Explanation:

Decreased melanin can occur in PKU because melanin is produced from phenylalanine and tyrosine. The defect in most children with PKU is deficiency of phenylalanine hydroxylase. Rare children have deficiency of biopterin cofactor due to a defect in its synthetic enzyme that is also autosomal recessive. Phenylalanine is converted to tyrosine by phenylalanine hydroxylase, so deficient tyrosine can occur in children on restrictive diets. PKU was prototype disorder for newborn metabolic screening, since infants with the disorder have no symptoms an d their severe intellectual disability can be prevented by dietary treatment. Those with biopterin deficiency do have early neurologic symptoms including seizures.

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1. A standard karyotypic analysis is ordered for a girl with heart defects, developmental delay, and an unusual appearance. The results are normal, but a colleague suggests the diagnosis of DiGeorge-velocardiofacial spectrum and recommends a FISH test with results shown in the figure A control probe highlights the chromosomes 22s in the metaphase spread and the test probe gives a signal on one of the chromosomes 22. Which of the following statements best summarizes this result?

The initial karyotype results are inconsistent with the FISH results.
This is a normal result, making the diagnosis of DiGeorge-velocardiofacial syndrome less likely.
A small deletion is present on one of the patient’s number 22 chromosomes, confirming the suspected diagnosis.
The FISH test was not useful, since the initial karyotype results were normal.
The chromosome with the positive signal is paternal in origin.

2. A female who is at risk to be a carrier of hemophilia A desires prenatal She does not want her extended family to know about her pregnancy if the fetus is affected. Which of the following prenatal diagnostic techniques should be advised?

Amniocentesis with western blot analysis of factor VIII
Chorionic villus sampling with DNA analysis for factor VIII mutations
Percutaneous umbilical blood sampling with testing of factor VIII levels
Amniocentesis with DNA analysis for factor VIII mutations
Chorionic villus sampling with assay of factor VIII activity

3. A 4-year-old African American girl presents with Prader-Willi syndrome obesity, short stature, hypogonadism, and mental disability. Despite a normal gestation and delivery, she had extremely low tone (hypotonia) in the newborn nursery and had to be tube-fed until age 6 months. At age 3 years, she began eating too much, taking food from her parents’ plates and even foraging in the garbage for food. Her physician suspects the diagnosis of Prader-Willi syndrome, and recalls that about 60% of Prader-Willi patients have a small deletion on the proximal long arm of chromosome 15. Which of the following techniques would be most accurate in testing for this deletion?

Standard karyotyping of peripheral blood leukocytes
Northern blotting of mRNAs transcribed from the deletion region
Restriction analysis to detect DNA fragments from the deletion region
Rapid karyotyping of bone marrow
Fluorescent in situ hybridization (FISH) analysis of peripheral blood lymphocytes using fluorescent DNA probes from the deleted region

4. A child is referred for evaluation because of low muscle tone and developmental delay. Shortly after delivery, the child was a poor feeder and had to be fed by tube. In the second year, the child began to eat voraciously and became He has a slightly unusual face with almond-shaped eyes and downturned corners of the mouth. The hands, feet, and penis are small, and the scrotum is poorly formed. The diagnostic category and laboratory test to be considered for this child are which of the following?

Sequence, serum testosterone
Single birth defect, serum testosterone
Deformation, karyotype
Syndrome, karyotype
Disruption, karyotype

5. A 14-year-old Caucasian adolescent has mild disability requiring resource classes and is obese because the parents have had great difficulty controlling her food intake at school and in her grandmother’s house where she goes after school. Her physician decides to test for Prader-Willi syndrome and knows that the paternal imprint on chromosome 15 is absent in this condition as opposed to the maternal imprint in Angelman A fluorescent in situ hybridization (FISH) test for chromosome 15 deletion had been normal when developmental delay was first suspected, but the physician decides that the girl’s increased appetite may reflect uniparental disomy (two chromosome 15 from one parent) that has caused a milder form of Prader-Willi syndrome. Southern blotting is performed to determine the origin of the patient’s number 15 chromosomes. In the figure below, a hypothetical Southern blot with DNA probe D15S8 defines which of four restriction fragment length polymorphisms (RFLPs) are present in DNA from mother (M), child (C), and father (F). Which of the following accurately conveys the result of this test?

Biparental origin of chromosome 15, confirming a diagnosis of Prader-Willi syndrome
Origin of both chromosome 15 from father, suggesting a diagnosis of Angelman syndrome
Origin of both chromosomes from the mother, suggesting a diagnosis of Prader-Willi syndrome
Absence of a paternal chromosome 15, diagnosing nonpaternity and excluding a diagnosis of Prader-Willi syndrome
Indeterminate result because the D15S8 locus is deleted in the child

6. The figure in Question 5 demonstrates that the child is missing both paternal chromosome 15 alleles; nonpaternity is a more plausible explanation than uniparental disomy. The hypothetical Southern blot shown below illustrates a DNA “fingerprinting” analysis to examine paternity, where maternal (M), child (C), and paternal (F) DNA samples have been restricted, blotted, and hybridized simultaneously to the probes D7Z5 and D20Z1. The distributions of restriction fragment alleles suggest which of the following?

The child is adopted
False maternity (ie, baby switched in the nursery)
False paternity
Correct maternity and paternity
None of the above

7. An infant with severe muscle weakness is born to a mother with mild muscle weakness and myotonia (sustained muscle contractions manifested clinically by the inability to release a handshake). The mother’s father is even less affected, with some frontal baldness and cataracts. Worsening symptoms in affected individuals of successive generations suggest which of the following inheritance mechanisms?

Genomic imprinting
Heteroplasmy
Unstable trinucleotide repeats
Multifactorial inheritance
Mitochondrial inheritance

8. Most isolated congenital anomalies exhibit which of the following?

Mendelian inheritance
Chromosomal inheritance
Multifactorial inheritance
Maternal inheritance
Atypical inheritance

9. A newborn Caucasian girl has bilateral club feet (feet deviated inward and malformed) with minimal movement of her lower She has a midline bulge over her lower spine that by MRI shows absent vertebrae with extrusion of spinal cord tissue and surrounding dura as a subcutaneous cyst. The lesion is diagnosed as spina bifida occulta and is known to follow the usual multifactorial determination of spina bifida and other common birth defects. Spina bifida exhibits female predilection with an incidence of 1 in 1000 Caucasian individuals and recurrence risks of 3% for first-degree relatives and 0.5% for second-degree relatives. The risk can be decreased by two-thirds if mother takes folic acid before conception. What is the risk that the parent’s second child will have spina bifida if mother takes folic acid before becoming pregnant?

1 in 1000
3 in 1000
1 in 100
3 in 100
Less than 0.1%

10. Neural tube defects, such as spina bifida and anencephaly, are best diagnosed by which of the following laboratory tests?

Chorionic villus biopsy and karyotype at 10 weeks after the last menstrual period (LMP)
Maternal serum α-fetoprotein (MSAFP) levels and ultrasound at 16 weeks after conception
Amniotic fluid α-fetoprotein (AFP) levels and ultrasound at 16 weeks after the LMP
Amniotic fluid acetylcholinesterase levels at 16 weeks after conception
Amniotic fluid karyotype and ultrasound at 16 weeks after the LMP

11. A couple has a child who has been diagnosed with medium-chain acyl-coenzyme A (CoA) dehydrogenase deficiency (MCAD-MIM*201450), a condition that affects the body’s ability to metabolize medium-chain fatty This couple is now expecting another child. What is the risk that this child will have MCAD?

12. In the treatment of propionic acidemia, which of the following is contraindicated?

Antibiotics
A diet high in fatty acids
Caloric supplementation
Aggressive fluid and electrolyte management
Hemodialysis

13. Which of the following is most likely in an untreated child with PKU?

Elevated tyrosine
Increased skin pigmentation
Decreased skin pigmentation
Normal phenylalanine hydroxylase levels
Elevated alanine

[MCQs] Genetic Medicine: Clinical Genetics and Inborn Errors of Metabolism Quiz – Part 2 (13 test)

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Genetic Medicine: Clinical Genetics and Inborn Errors of Metabolism - Part 2 (13 test)

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