Genetics MCN 568 UPDATED ACTUAL
Exam Questions and CORRECT Answers
Trisomy 18 (Edwards Syndrome) - CORRECT ANSWER - 2nd most common trisomy,
Mental deficiency, short sternum, syndactyly, GI anomalies, Cryptorchidism,
Rocker bottom feet , severe hypotonia
Prominent occiput
Clenched fists w/overlapping fingers , crossed legs,
Congenital heart defects
Horseshoe kidneys
IUGR/FTT , 50% die in first week,
90% die by age 1
Trisomy 21 (Downs Syndrome) - CORRECT ANSWER - most common trisomy
Hypotonia, flattened facial profile, poor moro, hyperflexibility, excess skin on neck, slanted eyes,
hip dysplasia, anomalous auricles, congenital heart defects, brushfield spots, protruding tongue,
single palmar crease, small nose, short stature and mental retardation, average age 45
Trisomy 13 (Patau Syndrome) - CORRECT ANSWER - Severe mental deficiency,
congenital heart defects, cleft lip, Holoprosencephaly, microcephaly, microphthalmia, deafness,
abnormal posturing of fingers, seizures, malformed ears, polydactyly, skin defects of posterior
scalp, hemangiomas, bicornuate uterus, cryptochidism. Survival 7 days.
Cri du chat syndrome - CORRECT ANSWER - deletion of short arm of chromosome 5
(paternal origin), severe mental retardation, cat-like cry, microcephaly, slow growth, hypotonia,
hypertelorism (wide spaced eyes), epicanthic folds, low-set ears. Can achieve
social/psychomotor level of 5-6 year old child.
Monosomy X (Turner Syndrome) - CORRECT ANSWER - produces X0 females, who are
sterile; most common abnormality in aborted fetuses (usually lethal inutero), paternal in origin,
ovarian dysgenesis, broad chest with wide spaced nipples, lymphedema, anomalous auricles,
, cubitus valgus, excessive pigmented nevi, renal anomalies, webbed neck, low hairline on neck,
normal intelligence and lifespan
XXX syndrome - CORRECT ANSWER - female, fertile, taller than average, serious
learning disabilities
XXY (Klinefelter Syndrome) - CORRECT ANSWER - Male phenotype, 50% miscarry,
Presence of BARR BODY (inactivated X chromosome), deficits in auditory and language, poor
psychosocial development, tall thin Long arms and legs, infertile, underdeveloped testes in boys,
breast development. increased incidence of breast cancer (20x normal male).
XYY syndrome - CORRECT ANSWER - Male, paternal nondisjunction, normal IQ, some
poor motor coordination, speech delay, learning disabilities, often with large teeth, prominent
glabella, long ears, long at birth, increased risk of behavioral problems (male juvenile
delinquents), normal fertility
autosomal dominant - CORRECT ANSWER - only one copy of the gene is required,
appears in every generation without skipping, transmitted on average to 50% of offspring.
unaffected people do not transmit the trait to their children. Males and females are equally
affected. Has variable expressivity.
autosomal recessive - CORRECT ANSWER - two copies of an abnormal gene must be
present in order for the disease or trait to develop. Trait appears only in siblings but not in
parents or other relatives. 25% transmission rate. Both males and females equally affected.
Constant expressivity. Increased incidence by consanguinity.
x-linked dominant - CORRECT ANSWER - affected males transmit trait to all daughters
but none of their sons. Affected females who are hetero transmit to half their children of either
sex. Females who are homo transmit to all of their children. Rare x-linked dominant, twice as
many females as males are affected.
X-linked recessive disorders - CORRECT ANSWER - Trait occurs almost exclusively in
males. Trait is passed from affected men to all of his daughters and half of his daughters sons.
Exam Questions and CORRECT Answers
Trisomy 18 (Edwards Syndrome) - CORRECT ANSWER - 2nd most common trisomy,
Mental deficiency, short sternum, syndactyly, GI anomalies, Cryptorchidism,
Rocker bottom feet , severe hypotonia
Prominent occiput
Clenched fists w/overlapping fingers , crossed legs,
Congenital heart defects
Horseshoe kidneys
IUGR/FTT , 50% die in first week,
90% die by age 1
Trisomy 21 (Downs Syndrome) - CORRECT ANSWER - most common trisomy
Hypotonia, flattened facial profile, poor moro, hyperflexibility, excess skin on neck, slanted eyes,
hip dysplasia, anomalous auricles, congenital heart defects, brushfield spots, protruding tongue,
single palmar crease, small nose, short stature and mental retardation, average age 45
Trisomy 13 (Patau Syndrome) - CORRECT ANSWER - Severe mental deficiency,
congenital heart defects, cleft lip, Holoprosencephaly, microcephaly, microphthalmia, deafness,
abnormal posturing of fingers, seizures, malformed ears, polydactyly, skin defects of posterior
scalp, hemangiomas, bicornuate uterus, cryptochidism. Survival 7 days.
Cri du chat syndrome - CORRECT ANSWER - deletion of short arm of chromosome 5
(paternal origin), severe mental retardation, cat-like cry, microcephaly, slow growth, hypotonia,
hypertelorism (wide spaced eyes), epicanthic folds, low-set ears. Can achieve
social/psychomotor level of 5-6 year old child.
Monosomy X (Turner Syndrome) - CORRECT ANSWER - produces X0 females, who are
sterile; most common abnormality in aborted fetuses (usually lethal inutero), paternal in origin,
ovarian dysgenesis, broad chest with wide spaced nipples, lymphedema, anomalous auricles,
, cubitus valgus, excessive pigmented nevi, renal anomalies, webbed neck, low hairline on neck,
normal intelligence and lifespan
XXX syndrome - CORRECT ANSWER - female, fertile, taller than average, serious
learning disabilities
XXY (Klinefelter Syndrome) - CORRECT ANSWER - Male phenotype, 50% miscarry,
Presence of BARR BODY (inactivated X chromosome), deficits in auditory and language, poor
psychosocial development, tall thin Long arms and legs, infertile, underdeveloped testes in boys,
breast development. increased incidence of breast cancer (20x normal male).
XYY syndrome - CORRECT ANSWER - Male, paternal nondisjunction, normal IQ, some
poor motor coordination, speech delay, learning disabilities, often with large teeth, prominent
glabella, long ears, long at birth, increased risk of behavioral problems (male juvenile
delinquents), normal fertility
autosomal dominant - CORRECT ANSWER - only one copy of the gene is required,
appears in every generation without skipping, transmitted on average to 50% of offspring.
unaffected people do not transmit the trait to their children. Males and females are equally
affected. Has variable expressivity.
autosomal recessive - CORRECT ANSWER - two copies of an abnormal gene must be
present in order for the disease or trait to develop. Trait appears only in siblings but not in
parents or other relatives. 25% transmission rate. Both males and females equally affected.
Constant expressivity. Increased incidence by consanguinity.
x-linked dominant - CORRECT ANSWER - affected males transmit trait to all daughters
but none of their sons. Affected females who are hetero transmit to half their children of either
sex. Females who are homo transmit to all of their children. Rare x-linked dominant, twice as
many females as males are affected.
X-linked recessive disorders - CORRECT ANSWER - Trait occurs almost exclusively in
males. Trait is passed from affected men to all of his daughters and half of his daughters sons.
