Nokea
Which is a sex chromosome abnormality that is caused by the presence of one or more additional X chromosomes in a male?
- A. Turner
- B. Triple X
- C. Klinefelter
- D. Trisomy 13
Correct Answer: C
Rationale: Klinefelter syndrome is characterized by one or more additional X chromosomes. These individuals are tall with male secondary sexual characteristics that may be deficient, and they may be learning disabled. An absence of an X chromosome results in Turner syndrome. Triple X and trisomy 13 are not abnormalities that involve one or more additional X chromosomes in a male (Klinefelter syndrome).
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Which genetic term refers to the transfer of all or part of a chromosome to a different chromosome after chromosome breakage?
- A. Trisomy
- B. Monosomy
- C. Translocation
- D. Nondisjunction
Correct Answer: C
Rationale: Translocation is the transfer of all or part of a chromosome to a different chromosome after chromosome breakage. It can be balanced, producing no phenotypic effects, or unbalanced, producing severe or lethal effects. Trisomy is an abnormal number of chromosomes caused by the presence of an extra chromosome, which is added to a given chromosome pair and results in a total of 47 chromosomes per cell. Monosomy is an abnormal number of chromosomes whereby the chromosome is represented by a single copy in a somatic cell. Nondisjunction is the failure of homologous chromosomes or chromatids to separate during mitosis or meiosis.
A woman, age 43 years, is 6 weeks pregnant. It is important that she be informed of which?
- A. The need for a therapeutic abortion
- B. Increased risk for Down syndrome
- C. Increased risk for Turner syndrome
- D. The need for an immediate amniocentesis
Correct Answer: B
Rationale: Women who are older than age 35 years at the birth of a single child or 31 years at the birth of twins are advised to have prenatal diagnosis. The risk of having a child with Down syndrome increases with maternal age. There is no indication of a need for a therapeutic abortion at this stage. Turner syndrome is not associated with advanced maternal age. Amniocentesis cannot be done at a gestational age of 6 weeks.
The nurse is teaching parents of a child with cri du chat syndrome about this disorder. The nurse understands parents understand the teaching if they make which statement?
- A. This disorder is very common.
- B. This is an autosomal recessive disorder.
- C. The crying pattern is abnormal and catlike.
- D. The child will always have a moon-shaped face.
Correct Answer: C
Rationale: Typical of this disease is a crying pattern that is abnormal and catlike. Cri du chat, or cats cry, syndrome is a rare (one in 50,000 live births) chromosome deletion syndrome, not autosomal recessive, resulting from loss of the small arm of chromosome 5. In early infancy this syndrome manifests with a typical but nondistinctive facial appearance, often a moon-shaped face with wide-spaced eyes (hypertelorism). As the child grows, this feature is progressively diluted, and by age 2 years, the child is indistinguishable from age-matched control participants.
Parents ask the nurse about the characteristics of autosomal recessive inheritance. Which is characteristic of autosomal recessive inheritance?
- A. Affected individuals have unaffected parents.
- B. Affected individuals have one affected parent.
- C. Affected parents have a 50% chance of having an affected child.
- D. Affected parents will have unaffected children.
Correct Answer: A
Rationale: Parents who are carriers of a recessive gene are asymptomatic. For a child to be affected, both parents must have a copy of the gene, which is passed to the child. Both parents are asymptomatic but can have affected children. In autosomal recessive inheritance, there is a 25% chance that each pregnancy will result in an affected child. In autosomal dominant inheritance, affected parents can have unaffected children.
Parents ask the nurse if there was something that should have been done during the pregnancy to prevent their childs cleft lip. Which statement should the nurse give as a response?
- A. This is a type of deformation and can sometimes be prevented.
- B. Studies show that taking folic acid during pregnancy can prevent this defect.
- C. This is a genetic disorder and has a 25% chance of happening with each pregnancy.
- D. The malformation occurs at approximately 5 weeks of gestation; there is no known way to prevent this.
Correct Answer: D
Rationale: Cleft lip, an example of a malformation, occurs at approximately 5 weeks of gestation when the developing embryo naturally has two clefts in the area. There is no known way to prevent this defect. Deformations are often caused by extrinsic mechanical forces on normally developing tissue. Club foot is an example of a deformation often caused by uterine constraint. Cleft lip is not a genetic disorder; the reasons for this occurring are still unknown. Taking folic acid during pregnancy can help to prevent neural tube disorders but not cleft lip defects.