Chromosome Abnormalities: Diagnosis and Mechanisms

Which of the following is a leading cause of structural and functional birth defects?

Which diagnostic technique is most effective for detecting microdeletions and microduplications of chromosomal segments?

Which of the following correctly differentiates Robertsonian translocation from nondisjunction in the context of Down syndrome?

Which diagnostic method is used for rapid detection of chromosomal aneuploidies in newborns?

How does nondisjunction during meiosis I result in numerical chromosomal imbalances?

Which of the following is TRUE regarding the genetic basis of Trisomy 18 (Edwards Syndrome)?

Which structural chromosomal abnormality results from the fusion of the long arms of two acrocentric chromosomes?

Why do individuals with Klinefelter syndrome (47, XXY) typically present with tall stature and hypogonadism?

A 12-week prenatal ultrasound shows a cystic hygroma. Which chromosomal abnormality is most likely?

Which of the following is NOT a diagnostic technique used for identifying 22q11.2 deletion syndrome (DiGeorge syndrome)?

How does the phenotype of Trisomy 13 (Patau syndrome) differ from Trisomy 18 (Edwards syndrome)?

Which of the following features is specific to Klinefelter syndrome (47, XXY)?

Why do chromosomal microdeletions result in syndromic phenotypes such as 22q11.2 deletion syndrome (DiGeorge syndrome)?

Which of the following chromosomal syndromes is NOT associated with advanced maternal age?

A neonate presents with microcephaly, rocker-bottom feet, and clenched hands with overlapping fingers. Which chromosomal abnormality is most likely?

How does the phenotype of Turner syndrome (45, X) differ from Klinefelter syndrome (47, XXY)?

Which inheritance pattern is observed in 22q11.2 deletion syndrome (DiGeorge syndrome)?

Why do individuals with Down syndrome have an increased risk of developing acute leukemia?

Which of the following is NOT a clinical feature of 22q11.2 deletion syndrome (DiGeorge syndrome)?

A neonate with Trisomy 13 (Patau syndrome) is likely to have which congenital anomaly?

Which of the following statements about Down syndrome (Trisomy 21) is TRUE?

Which clinical feature is NOT associated with Trisomy 18 (Edwards syndrome)?

Which of the following features distinguishes Klinefelter syndrome (47, XXY) from Turner syndrome (45, X)?

Why does mosaicism typically result in milder phenotypes compared to full chromosomal abnormalities?

Which structural abnormality results from a segment of a chromosome being reversed within itself?

A newborn presents with microcephaly, polydactyly, and holoprosencephaly. What is the most likely diagnosis?

How do numerical chromosomal abnormalities differ from structural chromosomal abnormalities?

Which of the following is a key feature of 22q11.2 deletion syndrome (DiGeorge syndrome)?

Why do individuals with Turner syndrome (45, X) experience primary amenorrhea and infertility?

A 1-year-old male presents with developmental delay, hypertelorism, and low-set ears. Genetic testing reveals a 22q11.2 deletion. Which clinical intervention is most critical for this patient?

Which of the following diagnostic techniques cannot detect balanced chromosomal rearrangements?

Which feature distinguishes mosaic Turner syndrome (45, X/46, XX) from classic Turner syndrome (45, X)?

Which of the following is a common cardiac abnormality in individuals with Down syndrome (Trisomy 21)?

Why do individuals with Klinefelter syndrome (47, XXY) have an increased risk of developing osteoporosis?

Which chromosomal syndrome is NOT associated with a high rate of spontaneous abortion?

A 45-year-old woman is pregnant and undergoes non-invasive prenatal testing (NIPT). The results indicate an increased risk of Trisomy 21. What is the next step in confirming the diagnosis?

Which chromosomal abnormality involves a deletion of a contiguous gene segment and presents with craniofacial anomalies, cardiac defects, and immune deficiency?

Which mechanism leads to the formation of Robertsonian translocation?

Why do individuals with Trisomy 18 (Edwards syndrome) rarely survive beyond infancy?

A newborn with Turner syndrome (45, X) should receive which initial evaluation to assess for associated medical complications?

Approximately what percentage of birth defects are attributed to chromosome imbalances?

Besides chromosomal abnormalities, what is another significant contributor to birth defects?

What proportion of conceptions are estimated to be lost due to chromosomal abnormalities?

If the rate of birth defects is 1 in 33 live births, approximately how many babies out of 1000 are affected by birth defects in the United States?

A researcher is investigating the causes of early pregnancy loss. Based on the information provided, which factor would be the MOST appropriate initial focus for their study?

What percentage of Down syndrome cases are attributed to Robertsonian translocation?

In Robertsonian translocation, which chromosomes are most commonly involved in the translocation leading to Down syndrome?

Which of the following mechanisms leading to Down syndrome is NOT related to maternal age?

A newborn presents with hypotonia, characteristic facial features of Down syndrome and a single palmar crease. Cytogenetic analysis is performed, but the lab reports mosaicism. What does mosaic Down syndrome imply about the individual's cells?

Which diagnostic test would be LEAST useful in detecting a Robertsonian translocation involving chromosome 21?

Which of the following physical features is LEAST likely to be observed in a newborn diagnosed with Trisomy 18 (Edwards Syndrome)?

A genetic analysis reveals that a child has an extra segment of chromosome 18 attached to another chromosome. This finding is most consistent with which type of Trisomy 18?

Which clinical manifestation in a neonate would raise the MOST suspicion for Trisomy 18 (Edwards Syndrome)?

A newborn presents with intrauterine growth restriction (IUGR), microcephaly, and a prominent occiput. Karyotype analysis is performed. Assuming the neonate has Trisomy 18, what is the MOST likely genetic abnormality that would be identified?

What is the underlying mechanism that leads to hypotonia and underdeveloped muscles, commonly observed in neonates with Trisomy 18 (Edwards Syndrome)?

What is the primary reason for the variability in phenotypic expression observed in individuals with mosaic Trisomy 18?

What is the most likely outcome for a conceptus with Trisomy 18?

A newborn presents with phenotypic abnormalities suggestive of Trisomy 18, but a standard karyotype is inconclusive. Which diagnostic test would be most effective in confirming mosaicism?

Among the mechanisms leading to Trisomy 18, which is least likely to result in full Trisomy 18?

Which management approach is generally considered the most ethically challenging in neonates diagnosed with Trisomy 18, given its prognosis?

What is the most common genetic etiology of Turner syndrome?

A prenatal ultrasound at 12 weeks reveals a cystic hygroma. Which of the following chromosomal abnormalities is most strongly suspected?

What is the most likely cause of monosomy X in Turner syndrome?

Which of the following is the MOST common karyotype found in individuals with mosaic Turner syndrome?

A patient with Turner syndrome is undergoing evaluation and management. Besides hormone replacement therapy, which of the following evaluations is MOST critical?

Besides growth hormone, which of the following hormone replacement therapies is indicated for pubertal development in a patient diagnosed with Turner syndrome?

A 1-year-old male presents with developmental delay, hypertelorism, slightly small and low set ears, a bulbous nose tip, a relatively long face, and a bifid uvula. Which of the following chromosomal abnormalities is MOST likely?

A 45,X/46,XX mosaic individual with mild Turner syndrome features seeks fertility counseling. Which of the following represents the MOST appropriate initial approach?

In the context of meiosis, what is the direct consequence of nondisjunction during Meiosis I?

A newborn infant presents with distinct facial features including upslanting palpebral fissures, a flat facial profile, and epicanthal folds. Which of the following clinical findings is also commonly associated with this condition?

Which of the following best describes the genetic etiology of Trisomy 21, the most common type of Down syndrome?

Prenatal screening for Down syndrome often includes assessing nuchal translucency (NT) in the first trimester. An increased nuchal translucency measurement in a 10-week gestation fetus raises suspicion for which of the following?

Refer to the provided diagram of meiosis and nondisjunction. If nondisjunction occurs during Meiosis II in one of the daughter cells from a normal Meiosis I, what is the expected chromosomal composition of the resulting four gametes?

A couple is undergoing genetic counseling due to a family history of Down syndrome. Diagnostic testing reveals that the proband has Trisomy 21. Assuming the mother is 30 years old and has a normal karyotype, and the father is 32 years old and also has a normal karyotype, what is the most probable meiotic event that led to Trisomy 21 in their child?

A newborn presents with hypotonia, a single palmar crease, and a protruding tongue. Karyotype analysis reveals 47, XX, +21. Which of the following best integrates the clinical findings and genetic result to arrive at the diagnosis?

Consider a scenario where nondisjunction occurs during both Meiosis I and Meiosis II in the same meiotic event. If Meiosis I nondisjunction results in disomic and nullisomic daughter cells, and subsequently, Meiosis II nondisjunction occurs in the disomic daughter cell only, what would be the distribution of chromosome number in the resulting gametes?

What approximate percentage of Down syndrome cases are attributed to standard Trisomy 21 caused by nondisjunction?

Which of the following chromosomal translocations is most commonly involved in Robertsonian translocation causing Down syndrome?

Which of the following diagnostic tests is LEAST likely to be used as a primary method for the initial detection of Trisomy 21?

Which of the following factors distinguishes Robertsonian translocation as a cause of Down syndrome FROM Trisomy 21 due to nondisjunction?

A newborn presents with clinical features suggestive of Down syndrome, and a karyotype reveals mosaicism. What does this finding imply regarding the individual's genetic makeup?

A 25-year-old male presents with tall stature, gynecomastia, and small testes. Hormonal analysis reveals low testosterone levels and elevated FSH and LH. Based on these findings, what is the most likely underlying genetic abnormality?

Which of the following findings is LEAST likely to be associated with Klinefelter syndrome?

A 14-year-old boy is diagnosed with Klinefelter syndrome. Which of the following interventions is MOST appropriate during puberty?

A 35-year-old male with known Klinefelter syndrome presents for a routine checkup. Considering the long-term health risks associated with this condition, which of the following screenings is MOST important?

What is the most likely meiotic error resulting in Klinefelter syndrome if the individual's karyotype is 47,XXY and the parents have normal karyotypes?

Which specimen is LEAST suitable for routine cytogenetic evaluation in a newborn suspected of having a chromosomal abnormality?

A couple with a history of multiple miscarriages is undergoing genetic testing. Which of the following would be the MOST appropriate initial diagnostic test to assess for chromosomal abnormalities?

Which of the following is BEST detected by chromosome microarray (CMA)?

A researcher is investigating the cause of aneuploidy in a population of aborted fetuses. Which meiotic event should be the PRIMARY focus of their investigation?

A fetus is suspected of having a chromosomal abnormality based on a positive prenatal screen. Which test is MOST appropriate for a rapid, initial assessment of common aneuploidies such as Trisomy 21, 18, and 13?

A couple presents for genetic counseling after their child is diagnosed with a de novo unbalanced translocation. The doctors want to determine which parent the translocation comes from to assess recurrence risk. What test is most appropriate to delineate the origin?

A researcher aims to identify the precise breakpoints of a newly discovered chromosomal translocation in a cancer cell line. Which of the following methods would offer the HIGHEST resolution for breakpoint mapping?

A cytogeneticist is analyzing a series of karyotypes and identifies a chromosome with two distinct centromeres. Which of the following terms BEST describes this type of abnormal chromosome?

What accounts for the majority of Trisomy 18 (Edwards syndrome) conceptuses?

A couple with a history of recurrent miscarriages is undergoing genetic counseling. Cytogenetic analysis reveals that the father carries a balanced translocation involving chromosomes 18 and 8. What is the most relevant risk associated with this finding regarding future pregnancies?

A neonate is suspected of having Trisomy 18. Initial karyotype results are inconclusive due to poor chromosome condensation. Which of the following diagnostic tests would be MOST appropriate to rapidly confirm the diagnosis?

A newborn is diagnosed with Trisomy 18 and presents with severe cardiac defects and respiratory distress. The parents are faced with the difficult decision of pursuing intensive medical intervention versus focusing on comfort care. What is the MOST important factor to consider when determining the most appropriate course of action?

A couple undergoes genetic counseling after the birth of their child who is diagnosed with mosaic Trisomy 18. The genetic counselor explains that mosaicism can result in a variable phenotype. Which of the following biological mechanisms BEST explains why mosaicism leads to phenotypic variability?

A prenatal ultrasound at 12 weeks gestation reveals a cystic hygroma. Which of the following chromosomal abnormalities is most strongly associated with this finding?

What is the most common genetic mechanism underlying Monosomy X (Turner syndrome)?

A 15-year-old female presents with short stature and lack of breast development. Physical examination reveals a webbed neck and widely spaced nipples. Which of the following hormonal profiles is most consistent with a diagnosis of Turner syndrome?

Which of the following is the MOST common type of Trisomy 13?

A newborn presents with several clinical features, including intrauterine growth restriction, microcephaly, and postaxial polydactyly. Which condition is MOST likely?

Which of the following is the MOST critical initial evaluation for a newborn diagnosed with Monosomy X (Turner syndrome), beyond karyotype confirmation?

Which of these diagnostic tests is LEAST likely to be used as a primary method for the initial detection of Trisomy 13 in a prenatal setting?

A 45,X/46,XX mosaic karyotype is identified in a female patient. Compared to classic Monosomy X (45,X), mosaic Turner syndrome is typically associated with:

Which of the following is NOT a typical management strategy for a newborn diagnosed with Trisomy 13?

A 1-year-old male presents with developmental delay, hypertelorism, low-set ears, a bulbous nose tip, a relatively long face, and a bifid uvula. While the text suggests a chromosomal abnormality, these features are MOST suggestive of which of the following?

Which genetic mechanism is LEAST likely to result in full Trisomy 13?

In managing a patient with Turner syndrome presenting with hypogonadism and delayed puberty, which of the following hormone replacement regimens is typically initiated by pediatric endocrinologists to induce pubertal development?

Considering the etiology of Monosomy X, if nondisjunction occurs during paternal meiosis I, what would be the expected sex chromosome complement of the sperm that, upon fertilization of a normal oocyte, results in a 45,X offspring?

Which of the following congenital anomalies is LEAST associated with Trisomy 13 (Patau Syndrome)?

A couple undergoes genetic counseling after the detection of Trisomy 13 in their fetus. Cytogenetic analysis reveals that the fetus has 46 chromosomes, but with an abnormal distribution of chromosome 13 material. Which mechanism is MOST likely?

A researcher is investigating potential therapeutic targets for Trisomy 13, focusing on genes within the critical region of chromosome 13 that contribute most significantly to the syndrome's phenotype. Animal models are used to assess the impact of gene overexpression and knockdown. Which approach would provide the MOST direct insight into understanding which specific genes are the primary drivers of key phenotypic features of Trisomy 13?

Leading cause of birth defects

Detecting microdeletions

Down syndrome causes

Rapid aneuploidy detection

Meiosis I nondisjunction

Mosaic Trisomy 18

Robertsonian translocation

Klinefelter syndrome features

Cystic hygroma

Diagnosing 22q11.2 deletion

Trisomy 13 features

Klinefelter syndrome

Microdeletions

Not linked to maternal age

Trisomy 18

Turner vs. Klinefelter

Inheritance of 22q11.2 deletion

Down syndrome and leukemia

Not a feature of DiGeorge

Key features of trisomy 13

Down syndrome risk factor

Not a feature of Trisomy 18

Klinefelter vs Turner

Mosaicism

Chromosomal inversion

Trisomy 13

Numerical vs. Structural

Key features of 22q11.2

Turner syndrome effects

Detects CNVs

Chromosome abnormalities

Chromosome imbalances

Karyotype

Chromosome Microarray (CMA)

Maternal Age & Chromosomal Aberrations

Robertsonian Translocation in Down Syndrome

Mosaic Down Syndrome

FISH (Fluorescent In Situ Hybridization)

Down Syndrome Management

Neonate with hypertonia

Nondisjunction

Genetic Patient Approach

Screening/Diagnostic Tests (Genetic)

Down Syndrome Phenotype

Brachycephaly

Upslanting Palpebral Fissures

Epicanthal Folds

Intrauterine Growth Restriction (IUGR)

Microcephaly

Clenched Hands w/ Overlapping Fingers

Omphalocele

PCR (Polymerase Chain Reaction)

Trisomy 18 Management

Turner Syndrome (Monosomy X)

Cause of Turner Syndrome

Hypogonadism in Turner Syndrome

Initial Evaluation for Turner Syndrome

Hormone Replacement in Turner Syndrome

Cystic Hygroma (Prenatal)

Physical features

Clues for Genetic Diagnosis

Nondisjunction in DS

Robertsonian Translocation (DS)

Down Syndrome Complications

Mosaic Trisomy 18 Definition

Causes of Trisomy 18

T18 Diagnostic Tests

Neonate Evaluation

Chromosome analysis

Cytogenetic Evaluation Samples

CMA Detection

Aneuploidy Definition

Chromosome Anatomy

Karyotype Definition

FISH

Hypogonadism in Klinefelter Syndrome

Gynecomastia in Klinefelter Syndrome

Body Proportions in Klinefelter Syndrome

Comorbidities Associated with Klinefelter Syndrome

Monosomy X

Turner Syndrome Cause

Initial Turner Syndrome Screen

Turner Syndrome Hormone Replacement

Dysmorphic Features

Karyotype Testing

What is Trisomy 13?

Trisomy 13 Phenotype

Holoprosencephaly

Diagnosing Trisomy 13

Trisomy 13 Prognosis