Genetic Counseling and Risk Assessment — Flashcards

Flashcard 1: A ring chromosome is denoted by the symbol _____ in human genetics.

Answer: r

Flashcard 2: A _____ score is calculated using the molecular tests for breast cancer, ranging from 0-100

Answer: recurrence

Flashcard 3: What is the mode of inheritence of Naxos syndrome?_____

Answer: Autosomal recessive

Extra: Naxos syndrome is characterized by the triad of: 1. Arrhythmogenic Right Ventricular Cardiomyopathy (ARVC) 2. Woolly hair 3. Palmoplantar keratoderma It is caused by a mutation in the **Plakoglobin** gene. Note: Carvajal syndrome is a similar autosomal recessive condition involving the **Desmoplakin** gene, typically presenting with left ventricular involvement.

Flashcard 4: Translocation in Philadelphia chromosome is best studied by using _____

Answer: FISH (Fluorescence In Situ Hybridization)

Extra: Philadelphia chromosome: t(9;22)(q34;q11). - **FISH** is the preferred method for detecting the translocation as it can be done on both metaphase and interphase cells. - **RT-PCR** is the most sensitive method, primarily used for monitoring Minimal Residual Disease (MRD). - **SKY** (Spectral Karyotyping) is typically reserved for complex chromosomal rearrangements where multiple chromosomes are involved.

Flashcard 5: _____ is a molecular test in breast cancer that is a 70-gene assay

Answer: Mammaprint

Flashcard 6: How can a Robertsonian translocation cause chromosomal imbalance in offspring? _____

Answer: A gamete containing the translocated chromosome is passed on alongside a normal copy of one of the involved chromosomes (e.g., t(14;21) + normal 21)

Extra: Robertsonian translocations involve two acrocentric chromosomes (13, 14, 15, 21, 22). Carriers have 45 chromosomes but are phenotypically normal. Imbalance occurs during meiosis when the translocated chromosome segregates with a normal homolog, resulting in trisomy (e.g., Trisomy 21) or monosomy in the offspring.

Flashcard 7: _____ syndrome is due to an inherited defect in DNA mismatch repair enzymes, resulting in microsatellite instability

Answer: Lynch

Flashcard 8: _____ syndrome is a disease from abnormal biogenesis of lysosome-related organelles with impaired melanosome maturation and absent dense bodies in thrombocytes.

Answer: Hermansky Pudlak

Flashcard 9: _____ syndrome is most commonly characterized by a 47,XXY karyotype

Answer: Klinefelter

Flashcard 10: In _____, 24 distinct fluorescent colours are made by mixing 5 fluorophores and each chromosome is identified by a unique colour.

Answer: Multicolour FISH