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Father has a trait, which is inherited in autosomal recessive mode of inheritance. Calculate the probability to have a daughter with a trait in marriage with a female who is a carrier of recessive allele.
The pedigree below represents a family with alkaptonuria from central Slovakia. The most likely mode of inheritance is: VISAR ATT INTE ALLA GENERATIONER AR AFFECTED
Diana’s father and her only son suffer from ocular albinism (lack of pigment in eyes). So do two of Diana’s nephews from sister. Diana’s brother’s children – a boy and a girl are healthy. Healthy is Diana’s mother, her husband, sister’s and brother’s spouses. Calculate the probability for Diana’s grandchildren to be healthy, if in her daughter-in-law’s family the disease was never registered. Select one:
A 28-year-old woman and a 25-year -old man present for genetic counseling. Both are white and have one sibling affected with cystic dbrosis. The most appropriate method to assess the risk of transmitting cystic dbrosis to a potential child would be
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The family below is segregating a mutation for Duchenne Muscular Dystrophy (DMD), a lethal X-linked recessive disorder. Filled symbols represent individuals affected with DMD. Individual III-1, 5 y.o., has muscle weakness and wasting, and has an abnormal muscle biopsy. Both III-1, and her sister III-2, aged 1 y.o., have normal karyotypes. What is the risk that III-2 is a carrier for DMD?
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What would be the sex of an XXY individual?
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Consider the following normal sequence of genes: a b c d e f g h a b c d e f g h. The sequence a b f e d c g h a b f e d c g h represents a (an)
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A point mutation that changes a codon specifying an amino acid into a stop codon is called a
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Twins are said to be concordant:
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Which of the following is the risk that an unaffected full sibling of a patient with cystic dbrosis (CF) carries a mutated CF gene?
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Which statement is not an assumption of the Hardy – Weinberg law?
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Which one of the following statements regarding prenatal diagnosis is accurate?
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Iris and Toby are considering pregnancy for the dfth time. They already have four children, all healthy and normal appearing. Toby and his mother have Crouzon syndrome, an autosomal dominant form of craniosynostosis (premature fusion of the skull bones) with a penetrance of 100 %. What is the risk for the dfth child to be affected ?
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Which of the following changes is a transition base substitution ?
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The pedigree chart below is for a family, some of whose members exhibit the autosomal dominant trait, brown eye color. Brown eyed individuals are indicated by a dark square or circle. Use the chart to answer the following question: what is the genotype of individual B-4.
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Which pedigree the best represent the mode of inheritance for an X linked recessive inheritance?
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Which one of the following should be offered amniocentesis for chromosome analysis?
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Amniocentesis is performed on a patient at 16 weeks gestation because of her age (she is 36). The dnal report to the physician says that the fetus has a 45,X/46,XX karyotype, wtih the 45,X cell line making up 90 % of the cells examined. The fetus will most likely have phenotypic features of which of the following syndromes ?
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A sample of 100 000 of human disclosed 30 persons ill with retinoblastoma (autosomal dominant trait). Calculate the frequency of the recessive allele in this population
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Which of the following is an example of monosomy?
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Which answer describes triploidy correctly?
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Which of the following is characteristic of the mitochondrial genome?
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Calculate and match correct frequency of insertion allele (I) of ACE gene using gell electrophoresis results.
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The pedigree chart below is for a family, some of whose members exhibit the autosomal dominant trait, brown eye color. Brown eyed individuals are indicated by a dark square or circle. Use the chart to answer the following question: what is the probability that individual D3 is Ww?
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In South Africa, variegate porphyria is found in white South Africans at a higher frequency than would be expected if the population was in Hardy-Weinberg eqiulibrium. This population originated from a small group of Dutch settlers. The most likely explanation for the high frequency of variegate in this population is:
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Huntington disease is an autosomal dominant disease in which those who are homozygous for the disease gene have a clinical course that is no different from that of heterozygotes. In a population where the frequency of the Huntington gene is 0.08, what is the frequency of those who are homozygous for the gene?
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A non-disjunction of chromosome 21 occurs during meiosis I in a woman. The non-disjoined chromosome 21 homologues go to the polar body. Which one of the following is the most likely outcome?
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Which of the following changes is a transversion base substitution ?
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Which one of the following is the most suitable specimen for cytogenetic analysis where the patient is a child with dysmorphic features and unexplained mental retardation ?
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Neurodbromatosis type 1 is one of the most common autosomal dominant disorders. A heterozygous woman with neurodbromatosis type 1 has an unaffected partner. Which of the following is correct regarding their children?
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What is coekcient of relationship between second cousin:
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Which pedigree represents X – linked dominant inheritance?
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A couple has just had a third miscarriage. They have had no succesful pregnancies. A review of the couple“s family histories reveals that the husband‘s sister has one child, but has had two miscarriages. The couple still wishes to have children, Which of the following is the best recommendation for how the couple should proceed?
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The patient has Rat occiput, Brushdeld spots, atrioventricular canal cardiac defect, single palmar creases. Match the correct diagnosis.
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In a chromosome inversion, what can be said about the genes on the inverted piece of the chromosome ?
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Which one of the following is a suitable specimen for cytogenetic analysis ?
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The patient is small for age infant with small facies, congenital heart defect, peculiar hand positioning, rocker – bottom heels. Match the correct diagnosis.
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The patient has holoprosencephaly, polydactyly, midline cleft lip and palate. Match the correct diagnosis.
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Males are more often affected by sex-linked traits than females because:
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Study Notes
Autosomal Recessive Inheritance
- A father with an autosomal recessive trait and a mother who is a carrier of the recessive allele have a 50% chance of having a daughter with the trait.
Alkaptonuria
- Alkaptonuria is most likely inherited in an autosomal recessive pattern.
Ocular Albinism
- Ocular albinism is an X-linked recessive disorder.
Cystic Fibrosis
- The most appropriate method to assess the risk of transmitting cystic fibrosis to a potential child is carrier testing.
Duchenne Muscular Dystrophy
- The risk of the sister, III-2, being a carrier for Duchenne Muscular Dystrophy is 50%.
XXY Individuals
- The sex of an XXY individual is male, and they have Klinefelter Syndrome.
Point Mutations
- A point mutation that changes a codon specifying an amino acid into a stop codon is called a nonsense mutation.
Concordant Twins
- Twins are said to be concordant when they both have a particular trait or disease.
Cystic Fibrosis Risk
- The risk that an unaffected full sibling of a patient with cystic fibrosis carries a mutated CF gene is 2/3 (66.6%).
Hardy-Weinberg Law
- The Hardy-Weinberg law assumes that there is no mutation, no gene flow, random mating, no genetic drift, and a large population size.
Prenatal Diagnosis
- Amniocentesis is a prenatal diagnostic test performed on a pregnant woman to assess the health of the fetus. It can detect chromosomal abnormalities and other genetic disorders.
Crouzon Syndrome
- The risk for the fifth child to be affected with Crouzon syndrome is 50%
Transition Base Substitution
- A transition base substitution is a type of point mutation where a purine base (A or G) is replaced by another purine base, or a pyrimidine base (C or T) is replaced by another pyrimidine base.
Pedigree Analysis
- Individual B-4 in the pedigree has a heterozygous genotype for brown eye color (Ww).
X-Linked Recessive Inheritance
- X-linked recessive traits are more common in males and are passed from a carrier mother to her sons; affected males cannot pass the gene to their sons.
Amniocentesis
- Amniocentesis should be offered for chromosome analysis to a pregnant woman with a history of recurrent miscarriages, advanced maternal age, or family history of genetic disorders.
45,X/46,XX Karyotype
- A fetus with a 45,X/46,XX karyotype has a mosaic form of Turner syndrome. This means that some cells contain a normal XX chromosome complement, while other cells only contain one X chromosome (45,X).
- The fetus will most likely have phenotypic features of Turner syndrome which include short stature, webbed neck, and heart problems.
Retinoblastoma
- The frequency of the recessive allele for retinoblastoma in the population is 0.006.
Monosomy
- Turner syndrome (45,X) is an example of monosomy.
Triploidy
- Triploidy is a condition in which a cell has three sets of chromosomes, instead of the normal two sets.
Mitochondrial Genome
- The mitochondrial genome is circular, contains fewer genes compared to the nuclear genome, and undergoes maternal inheritance.
ACE Gene Insertion Allele
- The frequency of the insertion allele (I) of the ACE gene can be calculated using gel electrophoresis results.
Pedigree Analysis
- The probability that individual D3 is Ww is 1/2 (50%).
Variegate Porphyria
- The high frequency of variegate porphyria in South Africa is likely due to a founder effect, which occurs when a small population descends from a few ancestors.
Huntington Disease
- The frequency of those who are homozygous for the Huntington gene is 0.0064.
Nondisjunction
- The most likely outcome of nondisjunction of chromosome 21 during meiosis I is the birth of a child with Down syndrome.
Transversion Base Substitution
- A transversion base substitution is a type of point mutation where a purine base is replaced by a pyrimidine base, or vice versa (A/G replaced by a C/T or C/T replaced by a A/G).
Cytogenetic Analysis
- A blood sample is the most suitable specimen for cytogenetic analysis in a child with dysmorphic features and unexplained mental retardation.
Neurofibromatosis Type 1
- Children of a heterozygous woman with neurofibromatosis type 1 and an unaffected partner have a 50% chance of inheriting the disorder.
Coefficient of Relationship
- The coefficient of relationship between second cousins is 1/16.
X-Linked Dominant Inheritance
- X-linked dominant inheritance means that the trait is expressed in both males and females who inherit the dominant allele. Affected females have a 50% chance of transmitting the trait to their children, regardless of sex. Affected males will pass the trait to all of their daughters but none of their sons.
Recurrent Miscarriages
- The couple's recurrent miscarriages could be due to a chromosomal abnormality, a genetic disorder in either partner, or a uterine problem.
Trisomy 18
- The patient's symptoms (Rat occiput, Brushfield spots, atrioventricular canal cardiac defect, single palmar creases) are consistent with Trisomy 18, also known as Edwards syndrome.
Chromosome Inversion
- Genes on the inverted piece of chromosome in a chromosomal inversion are in a reversed order.
Suitable Specimen for Cytogenetic Analysis
- A buccal swab (cheek swab) is a suitable specimen for cytogenetic analysis.
Trisomy 13
- The patient's symptoms (small for age infant with small facies, congenital heart defect, peculiar hand positioning, rocker-bottom heels) are consistent with Trisomy 13, also known as Patau Syndrome.
Holoprosencephaly
- The patient's symptoms (holoprosencephaly, polydactyly, midline cleft lip and palate) are consistent with Holoprosencephaly.
Sex-Linked Traits
- Males are more often affected by sex-linked traits than females because they only have one X chromosome, whereas females have two X chromosomes. Therefore, if a male inherits a recessive allele on his X chromosome, he will express the trait, while a female would need to inherit two copies of the recessive allele to express the trait.
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Description
In this quiz, you will calculate the probability of having a daughter with a specific trait that is inherited via autosomal recessive inheritance. You will consider the genetic background of both parents, where one is affected, and the other is a carrier of the recessive allele.
