front 1 A researcher adds colchicine and colcemid to cultured fibroblasts
before karyotyping. Dividing cells are arrested primarily in: | back 1 C. Metaphase |
front 2 A chromosome shows its centromere very close to one end, with a long
and a tiny arm. This morphology is best termed: | back 2 A. Acrocentric |
front 3 A human autosome has arms of roughly equal length with the centromere
near the midpoint. It is classified as: | back 3 D. Metacentric |
front 4 A student labels the chromosomal regions that cap the ends and
maintain stability after replication. These structures are: | back 4 B. Telomeres |
front 5 A cytogeneticist wants to highlight constitutive heterochromatin
adjacent to centromeres. Which banding method is most
appropriate? | back 5 C. C-banding |
front 6 A patient’s tumor sample is tested using a technique that compares
tumor DNA to reference DNA with red and green fluorochromes to detect
chromosomal copy-number changes. This method is: | back 6 A. Comparative genomic hybridization |
front 7 In comparative genomic hybridization, a chromosomal region appears
bright red when tumor DNA is compared to normal. This most strongly
suggests: | back 7 D. Duplication of that region |
front 8 In the same CGH experiment, a chromosomal segment appears
predominantly green. This indicates: | back 8 B. Deletion of that region |
front 9 A child with developmental delay undergoes high-resolution testing
that can detect uniparental disomy and loss of heterozygosity, does
not require dividing cells, and uses minimal DNA. The best test
is: | back 9 C. Cytogenomic microarray (CMA) |
front 10 Cytogenomic microarray is chosen over conventional karyotyping for
subtle copy-number changes. A key limitation of CMA is inability to
detect: | back 10 A. Balanced chromosomal rearrangements |
front 11 Which type of autosomal aneuploidy is generally better tolerated and
more compatible with live birth? | back 11 D. Trisomy compared with monosomy |
front 12 The most common underlying mechanism for human autosomal aneuploidy
(e.g., trisomies) is: | back 12 B. Meiotic nondisjunction in meiosis I or II |
front 13 A neonate has duodenal atresia with “double bubble” sign, hypotonia,
recurrent respiratory infections, leukemia risk, and a complete AV
canal defect. The most likely karyotype abnormality is: | back 13 C. Trisomy 21 |
front 14 A term infant with Down syndrome is evaluated for congenital heart
disease. Which combination best describes the typical cardiac defects
in this condition? | back 14 B. AV canal defect and ventricular septal defect |
front 15 In Down syndrome, overexpression of the DYRK1A gene on chromosome 21
primarily contributes to: | back 15 D. Learning and memory deficits |
front 16 A 39-year-old man with Down syndrome develops progressive cognitive
decline and dementia. Which gene’s triplication on chromosome 21 best
explains his early-onset Alzheimer pathology? | back 16 A. APP (amyloid precursor protein) |
front 17 A child has partial A21 that does not include the APP locus. Which
neurologic complication is notably unlikely even in adulthood? | back 17 C. Early-onset Alzheimer disease |
front 18 Among trisomy 13, trisomy 18, and trisomy 21, ventricular septal
defect is most frequent (≈90%) in which syndrome? | back 18 B. Trisomy 18 (Edwards) |
front 19 A newborn with severe growth restriction has microphthalmia,
post-axial polydactyly of the hands, and very poor postnatal survival.
The most likely diagnosis is: | back 19 D. Trisomy 13 (Patau syndrome) |
front 20 A 42-year-old woman asks about recurrence risk of Down syndrome in
future pregnancies. Age-related risk is primarily increased because
her oocytes: | back 20 A. Remain arrested in meiosis longer |
front 21 A short 15-year-old phenotypic female has primary amenorrhea, streak
ovaries, webbed neck, and lymphedema at birth. Karyotype shows: | back 21 C. 45,X |
front 22 A girl with Turner syndrome is found to have a cardiac murmur. Which
associated cardiac defect is most characteristic? | back 22 A. Bicuspid aortic valve |
front 23 The SHOX gene encodes a transcription factor expressed in embryonic
limb development. Its dosage effect is best summarized as: | back 23 D. More SHOX copies increase stature |
front 24 A tall, infertile male with testicular atrophy, low testosterone,
gynecomastia, and learning difficulties is evaluated. The likely
diagnosis and karyotype are: | back 24 B. Klinefelter syndrome, 47,XXY |
front 25 The pseudoautosomal region, which undergoes obligatory recombination
with X, is located on which chromosomal segment? | back 25 D. Distal Y pairing with X short arm |
front 26 An individual with an XX karyotype presents as a phenotypic male with
normal testes. This is most likely explained by: | back 26 A. SRY gene translocated onto X |
front 27 A newborn has karyotype 46,XY but lacks the SRY gene. Which phenotype
is most likely? | back 27 C. Normal phenotypic female with streak gonads |
front 28 A rearrangement causes loss of p arms from two nonhomologous
acrocentric chromosomes and fusion of their q arms at one centromere.
The individual has 45 chromosomes but appears normal. This
describes: | back 28 A. Robertsonian translocation |
front 29 A 6-month-old with microcephaly, severe intellectual disability, and
a characteristic high-pitched “cat-like” cry has karyotype
45,XY,del(5p). The diagnosis is: | back 29 D. Cri-du-chat syndrome |
front 30 A child presents with a “Greek warrior helmet” facial appearance and
severe developmental delay due to deletion of the distal short arm of
chromosome 4. This condition is: | back 30 B. Wolf–Hirschhorn syndrome |
front 31 A normal chromosome readout is “ABCDEFG.” A proband shows “ABEFG.”
This anomaly is best classified as: | back 31 C. Interstitial deletion |
front 32 A child with hypotonia, obesity, short stature, small hands and feet,
and intellectual disability is found to have a microdeletion of
15q11–q13. The syndrome is: | back 32 A. Prader–Willi syndrome |
front 33 A patient with mild intellectual disability, supravalvular aortic
stenosis, multiple pulmonary arterial stenoses, distinctive facies,
dental anomalies, and hyperglycemia has a microdeletion of 7q11
including ELN and LIMK1. Diagnosis? | back 33 D. Williams syndrome |
front 34 A child has thymic hypoplasia, conotruncal cardiac defects, secondary
hypocalcemia, and a 22q long-arm deletion. A clinically overlapping
condition with similar deletion is: | back 34 B. Velocardiofacial (VCF) syndrome |
front 35 A deletion of chromosome region 1p36 causes global developmental
delay, seizures, and intellectual disability. This region is
located: | back 35 C. Near telomeres, gene-dense region |
front 36 A child inherits both copies of chromosome 15 from the mother and
none from the father. This is an example of: | back 36 D. Uniparental disomy |
front 37 A karyotype shows two maternally derived homologs of chromosome 7,
one from each maternal homolog. This pattern is specifically
termed: | back 37 A. Heterodisomy |
front 38 Another patient has two identical copies of the same maternal
chromosome 7 homolog with no paternal contribution. This pattern
is: | back 38 C. Isodisomy |
front 39 A girl with Turner features has mosaic karyotype 45,X/46,XX. This
pattern best represents: | back 39 B. Somatic mosaicism |
front 40 A karyotype is reported as 46,Xr(X). Terminal deletions at both ends
of one X chromosome have occurred, and the ends fused. This is an
example of: | back 40 B. Ring chromosome formation |
front 41 Compared to a normal chromosome arrangement ABC/DEF, which of the
following represents a pericentric inversion? | back 41 B. ABD/CEF |
front 42 Which structural abnormality produces a chromosome with two copies of
one arm and complete absence of the other arm, often lethal due to
missing information? | back 42 A. Isochromosome |
front 43 A patient with chronic myelogenous leukemia has a shortened
chromosome 22 containing most of BCR and a segment of ABL from
chromosome 9. This derivative chromosome is known as the: | back 43 C. Philadelphia chromosome |
front 44 In chronic myelogenous leukemia, the ABL proto-oncogene is relocated
from 9q to 22q. This translocation produces: | back 44 C. Constitutive tyrosine kinase activity |
front 45 A child with a rapidly growing jaw mass is diagnosed with Burkitt
lymphoma. A reciprocal translocation t(8;14) moves which
proto-oncogene near the Ig heavy chain locus? | back 45 D. MYC |
front 46 In early cytogenetics, spindle poisons such as colchicine and
colcemid were added to cultured cells. Their primary effect was
to: | back 46 D. Arrest cells in metaphase for karyotyping |
front 47 In clinical cytogenetics, the karyotype of a patient best refers
to: | back 47 B. The number and types of chromosomes |
front 48 On a teaching slide, three human chromosomes are arranged left to
right, showing centromeres progressively closer to the tip. The
correct description from left to right is: | back 48 D. Metacentric, submetacentric, acrocentric |
front 49 A normal human somatic cell and a normal human gamete are both
considered karyotypically normal because they each: | back 49 A. Contain 23-chromosome multiples (euploid) |
front 50 During karyotyping, why are cultured metaphase cells exposed to a
hypotonic saline solution before slide preparation? | back 50 C. To swell and rupture metaphase cells |
front 51 A modern laboratory wants to perform standard banding to identify
each human chromosome by its characteristic dark–light pattern. The
most commonly used technique is: | back 51 B. Giemsa banding (G-banding) |
front 52 A lab performs reverse banding to visualize telomeric regions more
clearly. This method, compared with G-banding, requires: | back 52 D. Heat treatment, reversing dark–light pattern |
front 53 A cytogenetic workup includes both C-banding and NOR staining. These
techniques are specifically used to detect: | back 53 A. Constitutive heterochromatin and acrocentric satellites |
front 54 High-resolution banding in prophase or prometaphase increases total
visible bands from ~300–450 to ~800 because chromosomes at these
stages are: | back 54 C. More extended, less condensed structurally |
front 55 In cytogenetics, FISH is commonly used for targeted gene analysis.
FISH stands for: | back 55 D. Fluorescence in situ hybridization |
front 56 During FISH, the probe applied to the slide is best described
as: | back 56 B. Labelled single-stranded DNA segment |
front 57 Compared with high-resolution banding alone, a major advantage of
FISH for microdeletion testing is: | back 57 A. Higher resolution, greater specificity, ~1 Mb detection |
front 58 Spectral karyotyping (SKY) is a specialized karyotype method
that: | back 58 C. Uses FISH with multiple colored probes |
front 59 A patient undergoes array comparative genomic hybridization (aCGH).
This technique can reliably detect chromosomal duplications or
deletions as small as approximately: | back 59 D. 50–100 kilobases per segment |
front 60 A cell biologist describes a human cell as euploid. Which karyotype
pattern fits this definition? | back 60 B. Any chromosome count that is a multiple of 23 |
front 61 A conceptus with karyotype 69,XXX is: | back 61 A. Triploid polyploid with extra full set |
front 62 The most common mechanism producing human triploidy (e.g., 69,XXX or
69,XXY) is: | back 62 C. Dispermy at the time of fertilization |
front 63 A karyotype 47,XX,+21 is best described as: | back 63 D. Aneuploid trisomy, not a 23 multiple |
front 64 Across human conceptions, the single most common cause of aneuploidy
such as monosomy or trisomy is: | back 64 B. Nondisjunction in meiotic divisions |
front 65 A 2-month-old with trisomy 21 is being evaluated for major
comorbidities. The single most significant medical problem affecting
these patients is: | back 65 A. Structural congenital heart defect |
front 66 A newborn girl with Down syndrome has a loud systolic murmur and
failure to thrive. Echocardiography most likely shows: | back 66 C. Atrioventricular canal defect (AVSD) |
front 67 In addition to AV canal defects, which set of complications is
especially common in individuals with trisomy 21? | back 67 D. Sensorineural hearing loss, hypothyroidism, eye abnormalities |
front 68 More than 95% of Down syndrome cases arise from which
mechanism? | back 68 B. Meiotic nondisjunction |
front 69 A clinically normal woman under 30 has one child with trisomy 21 and
normal parental karyotypes. The recurrence risk is partly explained by
trisomy 21 confined to her germline. This pattern is: | back 69 D. Tissue-specific mosaicism |
front 70 A 40-year-old man with Down syndrome develops progressive memory loss
and cognitive decline. The third copy of which gene on chromosome 21
is most implicated? | back 70 A. APP |
front 71 The APP gene product most directly involved in Alzheimer pathology
is: | back 71 C. Amyloid β precursor protein |
front 72 A fetus is diagnosed with trisomy 18. Counseling notes that fewer
than 5% of conceptions survive to term. The classic full karyotype
notation in a male is: | back 72 D. 47,XY,+18 |
front 73 Which statement best explains why aneuploidy prevalence is lower in
females than males? | back 73 C. X inactivation masks mutant X alleles |
front 74 Compared with autosomal aneuploidy, sex chromosome aneuploidy tends
to be: | back 74 B. Clinically more severe |
front 75 A girl with short stature and primary amenorrhea has karyotype 45,X.
This monosomy is known as: | back 75 C. Turner syndrome |
front 76 A neonate with Turner syndrome (45,X) is most likely to show which
physical findings at birth? | back 76 B. Edema of ankles, wrists, webbed neck |
front 77 A 6-month-old with trisomy 21 has upslanting palpebral fissures and a
low nasal bridge. Which karyotype format correctly describes this
condition? | back 77 D. 47,XX or XY,+21 |
front 78 A 2-year-old with Down syndrome presents with bilious vomiting;
imaging shows duodenal obstruction. Which GI problems collectively
affect about 3% of children with trisomy 21? | back 78 D. Obstruction or atresia of esophagus, duodenum, anus |
front 79 A 3-year-old girl is noted to have her index finger overlapping the
middle finger at rest, along with growth restriction and congenital
heart disease. This hand finding is characteristic of: | back 79 C. Patau syndrome |
front 80 A teen with Turner syndrome is started on estrogen therapy. The main
goal is to promote: | back 80 B. Secondary sex characteristics |
front 81 A liveborn infant with Turner syndrome is later found to have a
normal 46,XX placenta with mixed 45,X/46,XX cells only in placental
tissue. This is best described as: | back 81 C. Germline-restricted mosaicism |
front 82 In Turner syndrome, mutation or haploinsufficiency of which gene is
strongly associated with short stature? | back 82 C. SHOX |
front 83 In cytogenetics, the p and q chromosome arms refer respectively
to: | back 83 A. Short arm, long arm |
front 84 Short stature in Turner syndrome is largely due to: | back 84 C. SHOX haploinsufficiency from single X copy |
front 85 The distal portion of the Y chromosome that pairs with X is called
the: | back 85 B. Pseudoautosomal region |
front 86 An XY individual lacking SRY due to abnormal crossover typically has
which gonadal finding? | back 86 D. Gonadal streak and poor secondary sex |
front 87 A tall, infertile man with atrophic seminiferous tubules and
gynecomastia has which classic karyotype? | back 87 A. 47,XXY |
front 88 Klinefelter syndrome (47,XXY) is best categorized as: | back 88 C. Sex chromosome aneuploidy |
front 89 The 47,XYY karyotype gained notoriety because of: | back 89 B. Higher incidence in prison populations |
front 90 Among known etiologies of pregnancy loss, the leading cause is: | back 90 D. Chromosome abnormalities |
front 91 Compared with balanced structural rearrangements, unbalanced
chromosome abnormalities usually: | back 91 A. Cause more severe clinical phenotypes |
front 92 A substance that promotes chromosome breakage in experimental
systems, such as ionizing radiation, is termed a: | back 92 C. Clastogen |
front 93 The exchange of chromosomal material between nonhomologous
chromosomes is called: | back 93 D. Translocation |
front 94 Which rearrangement preserves total genomic content via mutual
exchange between two nonhomologous chromosomes? | back 94 A. Reciprocal translocation |
front 95 A Robertsonian translocation is characterized by: | back 95 B. Loss of p arms, fusion of q arms |
front 96 Robertsonian translocations typically involve which chromosome
class? | back 96 C. Acrocentric chromosomes 13,14,15,21,22 |
front 97 In a Robertsonian carrier, alternate segregation during meiosis
produces gametes that are: | back 97 D. Balanced, either normal or carrier |
front 98 In a Robertsonian carrier, adjacent segregation during meiosis
principally results in: | back 98 B. Unbalanced gametes with trisomy, monosomy |
front 99 About 70% of Prader–Willi syndrome cases are due to: | back 99 D. Microdeletions of 15q |
front 100 The phenomenon in which phenotype depends on whether a deleted allele
is maternal or paternal is: | back 100 B. Genetic imprinting |
front 101 Supravalvular aortic stenosis is a hallmark cardiovascular lesion
in: | back 101 C. Williams syndrome |
front 102 SVAS in Williams syndrome is most directly linked to mutation of
which gene? | back 102 D. ELN |
front 103 The LIMK1 gene in Williams syndrome is most associated with defects
in: | back 103 B. Visual–spatial cognition |
front 104 Patients with Wolf–Hirschhorn syndrome may show WAGR features, which
include: | back 104 A. Wilms tumor, aniridia, GU anomalies, mental disability |
front 105 A child with Wilms tumor, aniridia, genitourinary anomalies, and
developmental delay is diagnosed with WAGR syndrome. At the
cytogenetic level, this is best classified as: | back 105 C. Contiguous gene syndrome |
front 106 Which description best defines a contiguous gene syndrome? | back 106 A. Deletion of several adjacent genes |
front 107 Microdeletions are typically: | back 107 D. <5 Mb, need banding or molecular |
front 108 Subtelomeric rearrangements usually involve: | back 108 B. Deletions or duplications in gene-rich telomeric regions |
front 109 In uniparental disomy, two identical copies of one parental homolog
define: | back 109 C. Isodisomy |
front 110 In uniparental disomy, two different homologs from one parent (one of
each) define: | back 110 A. Heterodisomy |
front 111 A child of healthy parents manifests an autosomal recessive disease,
and testing shows maternal uniparental isodisomy for that chromosome.
What is the best explanation? | back 111 A. Two identical maternal mutant alleles |
front 112 Unequal crossing over during meiosis most classically produces which
structural abnormality? | back 112 B. Duplications of chromosomal segments |
front 113 A chromosome with terminal deletions at both ends that subsequently
fuses to itself is called a: | back 113 A. Ring chromosome |
front 114 Which structural change results when a chromosomal segment is excised
and reinserted in reverse orientation? | back 114 C. Inversion |
front 115 A karyotype report describes an inversion including the centromere.
This is: | back 115 B. Pericentric inversion |
front 116 Phenotypically normal parents are found to carry a balanced
paracentric inversion. Their reproductive risk is primarily due to
gametes carrying: | back 116 D. Deletions or duplications from abnormal recombination |
front 117 A chromosome splits along the wrong axis, producing a chromosome with
two long arms and no short arm. This rearrangement is termed: | back 117 A. Isochromosome |
front 118 Isochromosomes are generally: | back 118 A. Lethal because of large deletions |
front 119 A patient has an isochromosome 18q with three copies of 18q and loss
of 18p. The clinical picture most closely resembles: | back 119 A. Edwards syndrome phenotype |
front 120 Which constellation of findings is most typical of major chromosome
abnormalities? | back 120 C. Developmental delay, dysmorphic facies, malformations |
front 121 A patient with chronic myelogenous leukemia has a shortened
chromosome 22 with a 9;22 reciprocal translocation. This derivative is
called the: | back 121 C. Philadelphia chromosome |
front 122 In the Philadelphia chromosome, which gene’s relocation is central to
pathogenesis? | back 122 D. ABL |
front 123 The abnormal ABL fusion protein in CML most directly causes: | back 123 B. Increased tyrosine kinase activity |
front 124 The Philadelphia chromosome is best described cytogenetically
as: | back 124 B. Balanced translocation affecting regulatory sequences |