Genetics Q

[MudPhud20XX]

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A 22-year-old male appears tall and thin, with relatively long arms. Puberty occurred at a normal age, but the physical examination reveals hypogonadism and underdeveloped secondary sexual characteristics. The laboratory results revealed decreased testosterone and elevated follicular stimulating hormone (FSH) and luteinizing hormone (LH). What is the most likely finding of a chromosome analysis?

 

[Missorleans]

XXY. Description fits kleinfelters exactly.

 

[MudPhud20XX]

XXY. Description fits kleinfelters exactly.

correct, Kleinfelter --> low testostereone, high FSH and LH

 

[MudPhud20XX]

A 27-year-old African American man is homozygous for the α-2c adrenergic receptor allele containing a 12 bp in-frame DNA deletion resulting in deletion of four amino acids. This allele is associated with earlier onset of heart failure, increased heart failure severity, and increased progression of severity. The frequency of this allele is 10 times higher in African Americans than whites and has an odds ratio of 5 compared to healthy African Americans. What is the risk for heart failure among African Americans homozygous for this allele compared with the risk for African Americans with other adrenergic receptor alleles?

 

[Transposony]

A 27-year-old African American man is homozygous for the α-2c adrenergic receptor allele containing a 12 bp in-frame DNA deletion resulting in deletion of four amino acids. This allele is associated with earlier onset of heart failure, increased heart failure severity, and increased progression of severity. The frequency of this allele is 10 times higher in African Americans than whites and has an odds ratio of 5 compared to healthy African Americans. What is the risk for heart failure among African Americans homozygous for this allele compared with the risk for African Americans with other adrenergic receptor alleles?

20%

 

[MudPhud20XX]

could you please explain?

 

[lunalight]

could you please explain?

I got the same answer. Risk is the reciprocal of the OR so you end up with: (5/1)^-1 = 1/5 = 20%

 

[lunalight]

A 27-year-old African American man is homozygous for the α-2c adrenergic receptor allele containing a 12 bp in-frame DNA deletion resulting in deletion of four amino acids. This allele is associated with earlier onset of heart failure, increased heart failure severity, and increased progression of severity. The frequency of this allele is 10 times higher in African Americans than whites and has an odds ratio of 5 compared to healthy African Americans. What is the risk for heart failure among African Americans homozygous for this allele compared with the risk for African Americans with other adrenergic receptor alleles?

The hardest part of that question is to figure out what it's asking without getting all turned around. Took me 3 reads before it clicked. Lol

 

[MudPhud20XX]

A 5-year-old boy is identified with mental impairment, downward dislocation of the lenses, mild scoliosis, pectus excavatum, and arachnodactyly. Increased levels of homocystine are identified in his urine. What gene is most likely mutated in this child?

 

[MudPhud20XX]

A 16-year-old boy is seen for the first time by a physician, who notes the patient was born with a cleft palate, microcephaly, and midface hypoplasia. A heart murmur was detected at 2 months of age. The patient had been treated many times for recurrent otitis media but had not had regular medical care. The physician noted a long face that appeared hypotonic with narrow palpebral fissures, puffy eyelids, a squared nasal root, and a narrow alar base with thin alae nasi. The mother demonstrated a similar but less severe constellation of features. Because a diagnosis was missing from the patient's chart, the physician ordered fluorescent in situ hybridization (FISH) analysis for both the mother and the patient. An abnormality is most likely to be found in what chromosome location?

 

[Missorleans]

Maybe velocardiofacial syndrome, chromosome 22, long arm.

 

[Missorleans]

A 5-year-old boy is identified with mental impairment, downward dislocation of the lenses, mild scoliosis, pectus excavatum, and arachnodactyly. Increased levels of homocystine are identified in his urine. What gene is most likely mutated in this child?

Homocystinuria. The most common defect is in the gene coding for cystethionine beta synthase. They didn't actually want the name of the gene did they?

 

[MudPhud20XX]

Maybe velocardiofacial syndrome, chromosome 22, long arm.

correct.

The symptoms described are consistent with velocardiofacial syndrome, part of the 22q11 syndrome (DiGeorge, Sedlackova, and velocardiofacial syndromes) caused by a three-megabase microdeletion at chromosome 22q11.

 

[MudPhud20XX]

Homocystinuria. The most common defect is in the gene coding for cystethionine beta synthase. They didn't actually want the name of the gene did they?

correct. they wanted the name of the gene which is cystathionine synthase. so it's homocystinemia = homocystinuria

An increased level of homocystine is the hallmark of homocystinuria, most often caused by a deficiency of cystathionine beta synthetase. It is often confused with Marfan syndrome because of an overlap in some symptoms, but elevated homocystine is not a feature of Marfan. Lens dislocation is generally upward in Marfan syndrome.

 

[MudPhud20XX]

Mary reports she is 16 weeks pregnant and undergoes screening for maternal serum alpha-fetoprotein (MSAFP) levels. Her MSAFP is 4.5 multiples of the appropriate gestational median (MoM). Assuming her pregnancy is correctly dated for gestational age, what should she be tested for?

 

[Missorleans]

Lol, most common cause of elevated AFP with correct dates is multiple gestation, they didn't say it's a singleton pregnancy.

 

[MudPhud20XX]

Lol, most common cause of elevated AFP with correct dates is multiple gestation, they didn't say it's a singleton pregnancy.

Correct! So is there a diff between just regular AFP and MSAFP? Or is all AFP MSAFP?

Multiple fetuses will cause an increase in MSAFP. This information and the correct gestational age are critical to correctly interpreting MSAFP.

 

[MudPhud20XX]

A full-term infant is born with ambiguous genitalia, and the laboratory quickly determines the infant's genotype is 46,XX. A mutation in the gene for which enzyme is life-threatening if not identified within the first day or two after birth?

 

[MudPhud20XX]

A 22-year-old male appears tall and thin, with relatively long arms. Puberty occurred at a normal age, but the physical examination reveals hypogonadism and underdeveloped secondary sexual characteristics. The laboratory results revealed decreased testosterone and elevated follicular stimulating hormone (FSH) and luteinizing hormone (LH). What is the most likely finding of a chromosome analysis?

 

[Missorleans]

A 22-year-old male appears tall and thin, with relatively long arms. Puberty occurred at a normal age, but the physical examination reveals hypogonadism and underdeveloped secondary sexual characteristics. The laboratory results revealed decreased testosterone and elevated follicular stimulating hormone (FSH) and luteinizing hormone (LH). What is the most likely finding of a chromosome analysis?

This is the same question as your first post.

 

[Missorleans]

A full-term infant is born with ambiguous genitalia, and the laboratory quickly determines the infant's genotype is 46,XX. A mutation in the gene for which enzyme is life-threatening if not identified within the first day or two after birth?

21 beta hydroxylase, ambiguous genitalia and salt wasting.

 

[MudPhud20XX]

21 beta hydroxylase, ambiguous genitalia and salt wasting.

correct.

 

[MudPhud20XX]

A twin study involving 2000 twin pairs showed 30% to 50% concordance for monozygotic (MZ) twins and insulin-dependent diabetes mellitus (IDDM) and 80% concordance for non–insulin-dependent diabetes mellitus (NIDDM). The concordance for dizygotic (DZ) twins was 15% for both types of diabetes. Based on these findings, describes the effect of genetic factors in diabetes.