Question 1

Which is a birth defect or disorder that occurs as a new case in a family and is not inherited?

Accepted Answer

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.

Question 2

A father with an X-linked recessive disorder asks the nurse what the probability is that his sons will have the disorder.Which response should the nurse make?

Accepted Answer

When a male has an X-linked recessive disorder,he has one copy of the allele on his X chromosome.The father passes only his Y chromosome (not the X chromosome)to his sons.Therefore,none of his sons will have the X-linked recessive gene.They will not be carriers or be affected by the disorder.No additional data are needed to answer this question.

Question 3

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?

Accepted Answer

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.

Question 4

Parents ask the nurse about the characteristics of autosomal recessive inheritance.Which is characteristic of autosomal recessive inheritance?

Accepted Answer

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.

Question 5

Turner syndrome is suspected in an adolescent girl with short stature.What causes this?

Accepted Answer

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.

Question 6

Which is a sex chromosome abnormality that is caused by the presence of one or more additional X chromosomes in a male?

Accepted Answer

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).

Question 7

Which genetic term refers to the transfer of all or part of a chromosome to a different chromosome after chromosome breakage?

Accepted Answer

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.

Question 8

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?

Accepted Answer

Typical of this disease is a crying pattern that is abnormal and catlike.Cri du chat,or cat's 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.

Question 9

A couple asks the nurse about the optimal time for genetic counseling.They do not plan to have children for several years.When should the nurse recommend they begin genetic counseling?

Accepted Answer

Persons who seek genetic evaluation and counseling must first be aware if there is a genetic or potential problem in their families.Genetic testing should be done now if the couple is part of a population at risk.It is not feasible at this time to test for all genetic diseases.The optimal time for genetic counseling is before pregnancy occurs.During the pregnancy,genetic counseling may be indicated if a genetic disorder is suspected.Congenital heart disease is not a single-gene disorder.

Question 10

A couple expecting their first child has a positive family history for several congenital defects and disorders.The couple tells the nurse that they are opposed to abortion for religious reasons.Which should the nurse consider when counseling the couple?

Accepted Answer

The benefits of prenatal diagnostic testing extend beyond decisions concerning abortion.If the child has congenital disorders,decisions can be made about fetal surgery if indicated.In addition,if the child is expected to require neonatal intensive care at birth,the mother is encouraged to deliver at a level III neonatal center.The couple is counseled about the advantages and disadvantages of prenatal diagnosis,not pregnancy termination,although the family cannot be forced to have prenatal testing.The information gives the parents time to grieve and plan for their child if congenital disorders are present.If the child is free of defects,then the parents are relieved of a major worry.

Question 11

Which is characteristic of X-linked recessive inheritance?

Accepted Answer

In X-linked recessive disorders,the affected individuals are usually male.With recessive traits,usually two copies of the gene are needed to produce the effect.Because the male only has one X chromosome,the effect is visible with only one copy of the gene.Females are usually only carriers of X-linked recessive disorders.The X chromosome that does not have the recessive gene will produce the "normal" protein,so the woman will not show evidence of the disorder.The transmission is from mother to son.Usually the mother and father are unaffected.

Question 12

The inheritance of which is X-linked recessive?

Accepted Answer

Hemophilia A is inherited as an X-linked recessive trait.Marfan syndrome and neurofibromatosis are inherited as autosomal dominant disorders.Fragile X is inherited as an X-linked trait.

Question 13

A couple has given birth to their first child,a boy with a recessive disorder.The genetic counselor tells them that the risk of recurrence is one in four.Which statement is a correct interpretation of this information?

Accepted Answer

Each pregnancy has the same risks for an affected child.Because an odds ratio reflects the risk,this does not change over time.The statement by the genetic counselor refers to a probability.This does not change over time.The statement "Because the parents have one affected child,the next child is four times more likely to be affected" does not reflect autosomal recessive inheritance.

Question 14

The nurse is reviewing a client's prenatal history.Which prescribed medication does the nurse understand is not considered a teratogen and prescribed during pregnancy?

Accepted Answer

Teratogens,agents that cause birth defects when present in the prenatal environment,account for the majority of adverse intrauterine effects not attributable to genetic factors.Types of teratogens include drugs (phenytoin [Dilantin],warfarin [Coumadin],isotretinoin [Accutane]).Heparin is the anticoagulant used during pregnancy and is not a teratogen.It does not cross the placenta.

Question 15

Parents ask the nurse if there was something that should have been done during the pregnancy to prevent their child's cleft lip.Which statement should the nurse give as a response?

Accepted Answer

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.

Question 16

Chromosome analysis of the fetus is usually accomplished through the testing of which?

Accepted Answer

Amniocentesis is the most common method to retrieve fetal cells for chromosome analysis.Viable fetal cells are sloughed off into the amniotic fluid,and when a sample is taken,they can be cultured and analyzed.It is difficult to obtain a sample of the fetal blood.It is a high-risk situation for the fetus.Fetal cells are not present in the maternal urine or blood.

Question 17

Which abnormality is a common sex chromosome defect?

Accepted Answer

Turner syndrome is caused by an absence of one of the X chromosomes.Down syndrome is caused by trisomy 21 (three copies rather than two copies of chromosome 21).Marfan syndrome is a connective tissue disorder inherited in an autosomal dominant pattern.Hemophilia is a disorder of blood coagulation inherited in an X-linked recessive pattern.

Question 18

Which genetic term refers to a person who possesses one copy of an affected gene and one copy of an unaffected gene and is clinically unaffected?

Accepted Answer

An individual who is a carrier is asymptomatic but possesses a genetic alteration,either in the form of a gene or chromosome change.Alleles are alternative expressions of genes at a different locus.A pedigree is a diagram that describes family relationships,gender,disease,status,or other relevant information about a family.Multifactorial describes a complex interaction of both genetic and environmental factors that produce an effect on the individual.

Question 19

A woman,age 43 years,is 6 weeks pregnant.It is important that she be informed of which?

Accepted Answer

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.

Question 20

Parents ask the nurse about the characteristics of autosomal dominant inheritance.Which statement is characteristic of autosomal dominant inheritance?

Accepted Answer

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.

Quiz 3: Hereditary Influences on Health Promotion of the Child and Family