Syndromes and recurrence risks chromosome abn

Question 1

What is common X;Y translocation?

Answer 1

46,X,der(X)t(X;Y)(p22.3;q11.2) in females

46,X,der(Y)t(X;Y)(p22.3;q11.2) in males

Question 2

What is the carrier rate of robertsonian translocations?

Answer 2

1/1000

Question 3

What is the risk of an abnormal liveborn child if the father carries a robtrans?

Answer 3

<1%

Question 4

What is the risk of an abnormal liveborn child if the mother carries a robtrans?

Answer 4

If 13/14/15/22 - <1%

If 21 involved - 10-15%

Question 5

What is the risk of an abnormal liveborn child with a UPD-associated disorder if either parent carries a robtrans?

Answer 5

0.5%

Question 6

If either parent are the carrier of a homologous robtrans, what is the risk of an abnormal liveborn child?

Answer 6

13;13 - very low risk of trisomy as most spont ab. Trisomy rescue is a possibility, but realistically this is incredibly rare.

14;14 - very low risk of trisomy as all spont ab. Trisomy rescue is a possibility, but realistically this is incredibly rare. If Trisomy rescue occurs, there is a risk of UPD14.

15;15 - very low risk of trisomy as all spont ab. Trisomy rescue is a possibility, but realistically this is incredibly rare. If Trisomy rescue occurs, there is a risk of UPD15.

21;21 - very low risk of trisomy as most spont ab. Trisomy rescue is a possibility, but realistically this is incredibly rare.

22;22 - very low risk of trisomy as all spont ab. Trisomy rescue is a possibility, but realistically this is incredibly rare

Question 7

Name a recurrent deletion or duplication syndrome on chromosome 1. If relevant, also name the gene involved.

Answer 7

1p36.3 deletion syndrome; ID, dysmorphic

Question 8

Name a recurrent deletion or duplication syndrome on chromosome 2. If relevant, also name the gene involved.

Answer 8

2q22.3 deletion - Mowat-Wilson syndrome (ZEB2); dysmorphic, dev del, hirschprung, ID

Question 9

Name a recurrent deletion or duplication syndrome on chromosome 4. If relevant, also name the gene involved.

Answer 9

Del 4p16.3 - WHS (WHCR).

HTT gene also in this region

Question 10

Name a recurrent deletion or duplication syndrome on chromosome 5. If relevant, also name the gene involved.

Answer 10

Del 5p15 - Cri-du-chat
Del5q22 - FAP (APC gene in this region)
Del5q35 - Sotos (NSD1)

Question 11

Name a recurrent deletion or duplication syndrome on chromosome 7. If relevant, also name the gene involved.

Answer 11

Del 7q11.2 - William syndrome (ELN)
7q31.2 - CFTR
UPD7 - RSS

Question 12

Name a recurrent deletion or duplication syndrome on chromosome 8. If relevant, also name the gene involved.

Answer 12

8q24.11 - Langer-Giedion (EXT1)

Question 13

Name a recurrent deletion or duplication syndrome on chromosome 9. If relevant, also name the gene involved.

Answer 13

Del 9p - sex reversal - DMRT1

Question 14

Name 2 recurrent deletion or duplication syndromes on chromosome 11. If relevant, also name the gene involved.

Answer 14

Del 11p13 - WAGR (PAX6, WT1)
11p15 - BWS
Del 11q23 - Jacobsen syndrome (FRA11B)

Question 15

Name a recurrent deletion or duplication syndrome on chromosome 12. If relevant, also name the gene involved.

Answer 15

47,XX,+i(12)(p) - Pallister-Killian

Question 16

Name a recurrent deletion or duplication syndrome on chromosome 13. If relevant, also name the gene involved.

Answer 16

Del 13q14.3 - Retinoblastoma - RB1

Question 17

Name a recurrent deletion or duplication syndrome on chromosome 14. If relevant, also name the gene involved.

Answer 17

UPD14

Question 18

Name a recurrent deletion or duplication syndrome on chromosome 15. If relevant, also name the gene involved.

Answer 18

UPD15

Del15q11.2 - PW/AS

Question 19

Name 2 recurrent deletion or duplication syndromes on chromosome 16. If relevant, also name the gene involved.

Answer 19

Del16p13.3 - ATR16 (Alpha-thal with MR)

Del16p13.3 - Rubenstien Taybi - CREBBP

Question 20

Name a 6 recurrent deletion or duplication syndromes on chromosome 17. If relevant, also name the gene involved.

Answer 20

Deletion 17p13.3 - Miller-Dieker (LIS1)
Deletion 17p11.2 - SMS (RAI1)
Duplication 17p11.2 - Potoki Lupski (RAI1)
Deletion 17p11.2 - HNPP (PMP22)
Duplication 17p11.2 - CMT1A (PMP22)
Deletion 17q11.2 - NF1

Question 21

Name a recurrent deletion or duplication syndrome on chromosome 20. If relevant, also name the gene involved.

Answer 21

Del 20p12 - Alagille syndrome (JAG1)

Question 22

Name 2 recurrent deletion or duplication syndrome on chromosome 22. If relevant, also name the gene involved.

Answer 22

Del 22q11.2 - DG

i(22)(q10) - Cateye syndrome

Question 23

Name a recurrent deletion or duplication syndrome on chromosome X. If relevant, also name the gene involved.

Answer 23

Del Xp21 - DMD
Del Xq28 - MECP2 (females only)
Dup Xq28 - MECP2 - males
Loss of Xq13-22 (POF1) - infertility in females
Loss of Xq23-27 (POF2) - infertility in females
Del Xp22 - SHOX, STS, KAL1, OA1, MRX, ARSE - various syndromes depending on extend of deletion

Question 24

Name a recurrent deletion or duplication syndrome on chromosome Y. If relevant, also name the gene involved.

Answer 24

i(Y)(p) - loss of AZF gene cluster - infertility
i(Y)(q) - loss of SRY, TS-like phenotype
inv(Y)(p;q) - common poly, but may interrupt AZF region

Question 25

How are risk figures devised from the data in Gardner and Sutherland?

Answer 25

Take the lowest risk figure from the translocation partners and divide by 2.

Question 26

``` Which diseases should be considered for unbalanced rob translocations involving: 13 14 15 21 22 ```

Answer 26

Patau (13;14 has a ~1% risk of liveborn patau) 14 - UPD 14 from trisomy rescue, but very rare 15 - UPD 15 from trisomy rescue, but very rare 21 - Down syndrome 22 - DiGeorge