10 - chromosomes Flashcards
List the clinical features of 1p36 del
Devdel, Hypotonia, delayed/absent speech, behavioural problems, eye defects (80% patients), distinctive facies
How can the 1q21 TAR syndrome micro deletion syndrome arise
The 1q21 region contains 4x large blocks of Low Copy Repeats (LCRs) which mediate NAHR
What are the features of TAR syndrome
TAR - thrombocytopenia Absent Radius Syndrome:
Absent Radii (bones in forearm) with presence of thumbs
Congenital / early onset thrombocytopenia
easy brushing and frequent nose bleeds
What micro deletion resides at 4p16
Wolf Hirchsorn
what are the clinical features of Wolf Hirchsorn Syndrome
1) typical facial appearance - greek warrior helmet
2) Growth delay
3) MR
4) Seizures
Cri-du-chat is caused by deletions where?
5p15.2
What are the clinical features of Cri-du-chat
1) High pitched monochromatic (cat-like) cry
2) microcephaly
3) MR
4) distinctive facial features
What is the likely inheritance of Cri-du-chat
80% de novo, 15-20% due to parental balanced structural rearrangment
what is the recurrence risk of 5p15.2 del
If arisen de novo, negligible.
If inherited, 8-18%
What micro deletion is associated with SOTOS
5q35
What are the causes of SOTOS syndrome
5q35 micro deletion encompassing the NSD1 gene most common, but SNVs in the NSD1 gene also a cause
What are the clinical features of SOTOS syndrome
Excessive Physical Growth in early years.
Leads to large body size
Macrocephaly
Characteristic facies with disproportionately large head
LD
7q11.23 deletion is associated with….
Williams Syndrome
what are the causes of Williams Syndrome
7q11.23 microdeletion
What is the causative gene in Williams Syndrome
ELN - encodes elastin
What are the clinical features of Williams syndrome
1) Cardiovascular disease
2) distinctive ‘elfin’ facies
3) connective tissue anomalies
4) mild LD
5) overly friendly, ‘cocktail party’ personality
Name a micro deletion syndrome on 7q21
Split hand/foot malformation
8p23.1 has both benign and pathogenic CNVs. What causes this
Due to unequal crossover between 2 olfactory receptor (OR) gene clusters flanking a 5mb region in 8p23.1
What are the features of the 8p23.1 microdeletion syndrome?
1) Dev delay
2) behavioural problems
3) congenital heart disease - due to GATA4 deficiency
4) diaphragmatic hernia
Name 4 conditions associated with Chromosome 11
1) Beckwith Wiedemann
2) Russell Silver
3) WAGR syndrome
4) Potock-Shaffer
What are the characteristics of WAGR syndrome
Caused by 11p13 deletion: W - Wilm's Tumour - caused by WT1 gene A - Aniridia - caused by PAX6 gene G - Genitourinary anomalies R - Retardation (mental)
What are the characteristics of 15q13.3 microdeletion syndrome
1) Neuro developmental issues - due to HI of CHRNA7 gene
2) inc devdel and delayed speech
3) epilepsy
4) variable penetrance - 75% inherited
The 16p13.3 micro deletion causes….
Rubinstein-Tayb syndrome
What are the characteristics of Rubinstein-Tayb syndrome
1) short stature
2) moderate to severe ID
3) distinctive facies
4) eye abnormalities
5) heart & kidney defects
Note: deletions are more severe and inc:
a) FTT
b) Seizures
