医学遗传学双语练习(单基因遗传)

医学遗传学双语练习（单基因遗传）
（此练习旨在帮助同学们了解英文题目）
Short-answer Questions简答题(用中文答题)
1. Draw a simple pedigree of three generations of a family to illustrate the transmission of an X-linked recessive disorder. (提示：注意XR遗传的特点)
2. List three differences between autosomal dominant inheritance and autosomal recessive inheritance.（提示：对比两种遗传方式的特点）
3. State the characteristics of X-linked dominant inheritance.
4. Explain what is meant by incomplete inheritance, with example.
5. Explain what is meant by expressivity, with example.
（此练习旨在帮助同学们了解英文题目）
Analysis and calculation 分析与计算(用中文答题)
1．Cathy is pregnant（怀孕）for the second time．Her first child，Donald，has CF(囊性纤维化)．Cathy has two brothers，Charles and Colin，and a sister，Cindy．Colin and Cindy are unmarried．Charles is married to an unrelated woman，Carolyn，and has a 2-year-old daughter，Debbie．Cathy’s parents are Bob and Betty．Betty’s sister Barbara is the mother of Cathy’s husband，Calvin，who is 25. There is no previous family history of CF．
a．Draw the pedigree，using standard symbols．
b．What is the pattern of transmission of CF，and what is the risk of CF for Cathy’s next child?
c．Which people in this pedigree are obligate heterozygotes (杂合子)?
d．Who is the proband in this family? What are the genotypes (基因型)of the proband and his/her parents?
2. The frequency of Tay-sachs(台萨斯）carrier is 1 /100 in a population.
(1)A couple with normal phenotype is unrelated. What is the risk of Tay-sachs disease for the
children of this couple?
(2)A normal man is married to his first cousin. What is the risk of Tay-sachs disease for the
children of this couple?
3. A positive carrier(肯定携带者) of albinism(白化病）marries his first cousin. What is the risk of their children？
4. Don and his maternal grandfather（外祖父）Barry both have hemophilia A（血友病A）. D on’s partner Diane is his maternal aunt’s daughter. Don and Diane have one son, Edward, and two daughters, Elise and Emily, all of whom have hemophilia A. They also have an unaffected daughter, Enid.
a. Drew the pedigree
b. Why are Elise and Emily affected?
c. What is the probability (概率) that a son of Elise would be hemophilic? What is the probability that her daughter would be hemophilic?
d. What is the probability that a son of Enid would be hemophilic? A daughter ?
5. Pedigree analysis (系谱分析)：①Judge the inheritance patterns of pedigrees and the genotypes (基因型)of the proband and his/her parents.②Gave your reason for judgement.
(系谱详见《医学遗传学讲授提纲》P45-46)
单项选择题
1. In X-linked recessive inheritance:
A. An affected male will have daughters who are all carriers.
B. An affected male may have affected father.
C. More female than males show the recessive phenotype（表现型）.
D. If a mother is a carrier her daughters are all carriers.
2. In achondroplasia(软骨发育不全) , homozygotes commonly do not survive the immediate postnatal period, heterozygotes are patients with. Which type in AD does it belong to?
A. Delayed Dominance（延迟显性）
B. Complete Dominance （完全显性）
C. Irregular Dominance （不规则显性）
D. Incomplete Dominance （不完全显性）
3. George and Grace，who both have normal hearing，have children；2 of their 5 daughters and 2 of their 3 sons are congenitally deaf（先天性耳聋）．How do you explain this phenomenon?
A. Irregular dominance（不规则显性）: the dominant disease-causing genes do not express in
George and Grace.
B. Variable expressivity（表现度变异）: disease is more severe in children than in parents.
C. Autosomal recessive inheritance（常染色体隐性遗传）: George and Grace are carriers of
congenitally deaf.
D. Genetic heterogeneity（遗传异质性）:the locus for recessive disease-causing genes in
husband differs from that in wife.
4. A couple both with inborn deaf have 6 children, all with normal hearing．How do you explain this phenomenon?
A. Irregular dominance（不规则显性）: the dominant disease-causing genes do not express in
all children.
B. Variable expressivity（表现度变异）: disease is more severe in parents than in children.
C. Autosomal dominant inheritance（常染色体显性遗传）: all children do not have any
disease-causing gene.
D. Genetic heterogeneity（遗传异质性）:the locus for recessive disease-causing genes in
husband differs from that in wife.
5. The probability （概率）that a genotype will express intending phenotype is
A. penetrance （外显率）
B. the risk of a disorder (发病风险)
C. expressivity （表现度）
D. the incidence of a disease （发病率）
6. The penetrance of polydactyl (多指症）may be about 80% in a population. A woman with polydactyl marries a normal man. What is the risk of polydactyl for the children of this couple?
A. 25%
B. 40%
C. 50%
D. 75%。