Nokea
Which is a birth defect or disorder that occurs as a new case in a family and is not inherited?
- A. Sporadic
- B. Polygenic
- C. Monosomy
- D. Association
Correct Answer: A
Rationale: Sporadic describes a birth defect previously unidentified in a family. It is not inherited. Polygenic inheritance involves the inheritance of many genes at separate loci whose combined effects produce a given phenotype. Monosomy is an abnormal number of chromosomes whereby the chromosome is represented by a single copy in a somatic cell. A nonrandom cluster of malformations without a specific cause is an association.
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The nurse is assessing a neonate who was born 1 hour ago to healthy white parents in their early forties. Which finding should be most suggestive of Down syndrome?
- A. Hypertonia
- B. Low-set ears
- C. Micrognathia
- D. Long, thin fingers and toes
Correct Answer: B
Rationale: Children with Down syndrome have low-set ears. Infants with Down syndrome have hypotonia, not hypertonia. Micrognathia is common in trisomy 16, not Down syndrome. Children with Down syndrome have short hands with broad fingers.
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.
Parents ask the nurse about the characteristics of autosomal dominant inheritance. Which statement is characteristic of autosomal dominant inheritance?
- A. Females are affected with greater frequency than males.
- B. Unaffected children of affected individuals will have affected children.
- C. Each child of a heterozygous affected parent has a 50% chance of being affected.
- D. Any child of two unaffected heterozygous parents has a 25% chance of being affected.
Correct Answer: C
Rationale: In autosomal dominant inheritance, only one copy of the mutant gene is necessary to cause the disorder. When a parent is affected, there is a 50% chance that the chromosome with the gene for the disorder will be contributed to each pregnancy. Males and females are equally affected. The disorder does not skip a generation. If the child is not affected, then most likely he or she is not a carrier of the gene for the disorder. In autosomal recessive inheritance, any child of two unaffected heterozygous parents has a 25% chance of being affected.
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.
Turner syndrome is suspected in an adolescent girl with short stature. What causes this?
- A. Absence of one of the X chromosomes
- B. Presence of an incomplete Y chromosome
- C. Precocious puberty in an otherwise healthy child
- D. Excess production of both androgens and estrogens
Correct Answer: A
Rationale: Turner syndrome is caused by an absence of one of the X chromosomes. Most girls who have this disorder have one X chromosome missing from all cells. No Y chromosome is present in individuals with Turner syndrome. These young women have 45 rather than 46 chromosomes.