Chromes

Question 1

Imprintable chromosomes

Answer 1

6, 7, 11, 14, 15, 16, and 20

Question 2

Most common Robertsonian translocation

Answer 2

t(14;21)

Question 3

All Robertsonian chromes and some homologous translocations will display _______

Answer 3

Uniparental inheritance

Question 4

Recombinant chromosome

Answer 4

A further rearrangement from a parental inversion

The larger the inversion, the smaller the recombination

Shows up on MA as a dup on one end a del on the other

Question 5

Classic chrome instability syndromes and their inheritance patterns

Answer 5

Fanconi anemia
Ataxia-telangiectasia
Bloom syndrome

All autosomal recessive

Question 6

What chemical is used in chrome breakage studies

Answer 6

A cross-linking agent (also referred to as a clastogen (i.e. diepoxybutane)

Question 7

Paracentric inversion

Answer 7

Does not involve the centromere

Yields either a balanced allele - could be normal or recombinant - or an inviable allele with either two centromeres or no centromeres

The chance of a paracentric inversion carrier having a live born child w/an abnormal ktype is very low.

Question 8

Pericentric inversion

Answer 8

Involves the centromere

Leads to either a balanced allele - normal or recombinant or an unbalanced, recombinant allele

The carrier of a pericentric inversion has ~5-10% risk of having a live-born child w/an abnormal ktype.

Question 9

Inversion Loop

Answer 9

Formed when an inverted chrome is present to allow alignment and pairing of homologous segments of the normal and inverted chromosomes in meiosis I.

Question 10

How/when does trisomy 21 occur

Answer 10

90% of the time it’s due to maternal meiosis I

10% due to paternal meiosis II

Question 11

Isodisomy

Answer 11

Chromosomes derived from identical sister chromatids (a type of UPD)

Question 12

Heterodisomy

Answer 12

Chromosomes derived from both homologous from one parent (a type of UPD)

Question 13

Underlying pathogenomic mechanism of UPD

Answer 13

Abnormal chromosome segregation, aka nondisjunction

Question 14

Common chromosomal abnormalities observed in DLBCL

Answer 14

25-35% of DLBCL cases have a t(14;18), usually in the context of a complex karyotype with additional anomalies. Additional abnormalities include rearrangements of 1q and 3q, del(6q), +7, +8, del(10q), del(11q), +12, del(13q), rearrangements of 14q and 17p, +der(18)t(14;18), and + X.