Metaphase Analysis

Question 1

Prenatal sample analysis

Answer 1

15 colonies from a minimum of two coverslips.
To rule out mcc and pseudomosaicism.
50 cells analyzed to r/o mosaicism

Question 2

Oncology sample analysis

Answer 2

Myeloid leukemias (24&48)
Lymphocytic leukimias(24&72)
Tcell disease= 72 hr pha
Bcell disease=72 hr lps

Question 3

Modal number

Answer 3

The most common chromosome count recorded from a given cytogenetic preparation

Question 4

Range

Answer 4

The number of chromosomes observed in all the cells of a population

Question 5

Nondisjunction( mechanism of aneuploidy)

Answer 5

Failure of paired chromosomes ( meiosis I) or sister chromatids ( meiosis II or mitosis) to separate at anaphase.
Nondisjunction in MI or M II= abnormal division can result in a constitutionally abnormal individual
Nondisjunction in Mitosis= abnormal division will result in a mosaic individual

Question 6

Anaphase lag

Answer 6

The mechanism of aneuploidy when a chromosome lags behind as the spindle separates the chromosomes to opposite poles

Question 7

Interchromosomal rearrangements

Answer 7

Reciprocal translocations= balanced exchanges of genetic material between two or more chromosomes( no genetic material is lost)

Question 8

Interchromosomal rearrangements

Answer 8

Robertsonian translocations= occur when there is a fusion in the centromere region between two acrocentric chromosomes.
2/3 risk of having abnormal conceptions
Common:
Der(13;14)(q10;q10)
Der(14;21)(q10;q10)