Microdeletions, Microduplications and Contiguous Gene Disorders Flashcards
________ ________ __________ is a small segment of extra or missing DNA
copy number variation (CNV)
_________ is 0 or 1 copy of the region
deletion (loss)
__________ is 3 or more copies of the region
duplication (gain)
_________ deletions/duplications are 3-5 Mb and can be seen on a karyotype
classic
___________ are smaller than 3 Mb and can be detected by FISH, CMA etc
microdeletions
___________ is when one copy of the gene is not sufficient
haploinsufficiency
_________________ is when three copies of the gene is too much
triplosensitivity
Are deletions or duplications more likely to be pathogenic?
deletions
___________/_________________ _____________ are disorders due to the deletion or duplication of two or more genes located in proximity to each other
Microdeletion/duplication syndromes
_____________(acronym) causes 10-22% of structural rearrangements
Interchromosomal – between homologs
Intrachromosomal – between sister chromatids
Intrachromatid – within the same chromosome
NAHR- non-allelic homologous recombination
- repetitive sequences
________________________ structural rearrangements between homologs
interchromosomal
________________________ structural rearrangements between sister chromatids
intrachromosomal
________________________ structural rearrangements within the same chromosome
intrachromatid
Microdeletion/microduplication syndrome phenotype?
Developmental Delay
Intellectual Disability
Dysmorphism
Organ malformation
Two examples of microdeletion syndrome?
RBM8A and TAR (thrombocytopenia absent radii syndrome)
Biotinidase deficiency
Inheritance pattern of microdeletion syndrome?
De novo or autosomal dominant - 22q microdeletion syndrome
4p deletion syndrome
Wolf-Hirschhorn syndrome
5p deletion syndrome
Cri du Chat syndrome
10p13 deletion syndrome
DiGeorge II syndrome
7q11.2 deletion syndrome
Williams (Williams-Beuren) syndrome
15q11-q13 deletion syndromes
PWS/Angelman
16p13.3 deletion
Rubinstein Taybi syndrome (CBP - creb binding protein)
#1 cause of autism spectrum disorder
17p11.2 deletion
Smith Magenis syndrome
17p11.2 duplication
Potocki/Lupski syndrome
22q11.2-q11.23 deletion or duplication?
22q11.2-q11.23 deletion or duplication syndrome
Most common microdeletion syndrome?
22q11.2 syndrome
Four genes in 22q11.2 region of deletion
TBX1 – implicated in cardiac- VSD, Tetralogy of Fallot, Aortic arch anomalies, palate defects
COMT – evidence that may be critical gene w/ regard to the psychiatric problems
SNAP29 – implicated in cutaneous and other atypical findings seen in some individuals w/ deletion»_space; Cerebral dysgenesis, neuropathy, ichthyosis, and palmoplantar keratoderma syndrome
PROHD»_space; risk psychiatric illness Jacquet 2002 PMID 12217952
22q11.2 inheritance
93% de novo
7% familial
3 main disorders of infancy with heart defects
- Aneuploidy
- Noonan syndrome
- 22q11.2 deletion syndrome
22q11.2 deletion phenotype faces?
Eye structures
Epicanthal folds
Hooded eyelids
Dark/red under-eyes (suborbital congestion)
Nose structure
Broad nasal bridge
Tubular nose shape
Bulbous nasal tip
Nostril sidewalls underdeveloped (hypoplastic alae nasi)
Ear Structure
Small or protuberant ears
Thick/overfolded helix
Low-set, posterior rotated
Preauricular pits/tags
Boney structures
Micrognathia
Malar flattening (underdeveloped cheekbones)
Small Teeth
Other
Asymmetrical crying face
Downturned mouth
22q11.2 deletion critical gene responsible for congenital heart disease (VSD, TOF), abnormal facies, thymic aplasia and hypocalcemia?
T-box 1 (TBX1)
22q11.2 deletion syndrome has _____________ penetrance and __________ expressivity
complete penetrance, variable expressivity
FISH probe for 22q11.2 deletion syndrome? ** CMA better **
TUPLE1/HIRA (Histone cell cycle Regulation defective S. cerevisiae homolog of A)
DiGeorge syndrome II gene region?
10p14-p13
Gene for autosomal dominant CHARGE syndrome?
CHD7
Chromodomain-helicase-DNA-binding protein 7
CHARGE syndrome phenotype?
Coloboma
Heart defects
Atresia of choanae
Retardation of growth and development
Genital hypoplasia
Ear abnormalities
AR conditions associated with 22q11.2 deletion syndrome?
SNAP29 -Cerdnik syndrome
GP1BB - Bernard Soulier syndrome
CDC45- craniosynostosis
SCARF2 - Van den Ende -Gupta syndrome
TANGO2 - encephalomyopathic and neurodegeneration
22q11.2 duplication syndrome phenotype
milder than deletion and variable, inherited from parent
-heart defects
-urogenital anomalies
-velopharyngeal insufficiency with or without cleft palate
-feeding problems
-hearing impairment
-facial dysmorphism
der(22)t(11;22) syndrome
Emanuel syndrome
inv dup of 22
Cat eye syndrome
Incidence of 22q11.2 deletion syndrome
1 in 4,000 (to 6,000)
Incidence of 4p16 deletion syndrome?
1 in 50,000 births
Three genes of 4p16 deletion (Wolf Hirschhorn) syndrome?
WHSC1, LETM1 and MSX1 - functions largely unknown in development
4p16 deletion (Wolf Hirschhorn) syndrome phenotype
Greek warrior helmet
colobomas
CHDs
GU
ID, seizures, microcephaly
4p16 deletion (Wolf Hirschhorn) syndrome inheritance?
De novo
5p microdeletion syndrome incidence?
1 in 50,000 (15,000 - 50,000)
5p microdeletion syndrome phenotype?
Laryngeal malformation - Cri du Chat - 5p15.3
Hypotonia
Microcephaly
Facial features
Cleft palate/lip
Male genital anomalies - cryptorchidism, hypospadias
Renal anomalies
Syndactyly
5p microdeletion syndrome facial features?
*Head
Microcephaly
Round face
Micrognathia
*Eyes
Hypertelorism
Epicanthal folds
Down slanting palpebral fissures
*Ears
Low set or malformed ears
*Mouth
Dropped-jaw/open-mouth expression (secondary to facial laxity)
Malocclusion of the teeth
In 80% of the 5p microdeletion cases, there was __________ (maternal/paternal) inheritance?
paternal
Incidence of 7q11.23 microdeletion syndrome
1 in 10,000
1 in 1750 with inversion
Williams (-Beuren) syndrome
Critical gene in 7q11.23 microdeletion syndrome?
ELN - elastin
Phenotype for 7q11.23 microdeletion syndrome?
supravalvular aortic stenosis (SVAS)
autosomal dominant cutis laxa
stellate/lacy iris
broad forehead, bitemporal narrowness
hoarse voice
hypercalcemia, hypercalciuria
ID
Strengths in short term memory
Deficits in visuospatial memory
Overfriendliness, empathy, anxiety, ADD
Inheritance for 7q11.23 microdeletion syndrome?
De novo
7q11.23 microduplication syndrome phenotype?
Social phobia/anxiety
Language delay with mild visuospatial impairment
Macrocephaly
Dilation of ascending aorta
Seizures and hypotonia
17p12 microdeletion vs microduplication syndromes? *bonus
microdeletion - HNPP - PMP22
microduplication - CMT - PMP22
17p11.2 microdeletion vs microduplication syndromes?
microdeletion - Smith Magenis syndrome
microduplication - Potocki Lupski syndrome
Critical gene for 17p11.2 microdeletion/microduplication syndromes?
RAI1 -retinoic acid inducer gene
Incidence of 17p11.2 microdeletion syndrome?
1 in 25,000 (to 15,000)
Smith Magenis syndrome
Phenotype of 17p11.2 microdeletion syndrome?
Tented upper lip, deep set eyes, coarse features
Inverted sleep pattern
Intolerance to ambient noise
autism, self hug
Onychotillomania
Dermatillomania
Inheritance of of 17p11.2 microdeletion syndrome?
De novo (almost all)
Incidence of 17p11.2 microduplication syndrome?
1 in 25,000
Potocki Lupski syndrome
Phenotype of of 17p11.2 microduplication syndrome?
Hypotonia/FTT
Sleep apnea
autistic
broad forehead
triangular to oval face
heart defects