10/15 - Segmental Aneusomy & Contiguous Gene Syndromes Flashcards Preview

Chromosomes Exam 2 > 10/15 - Segmental Aneusomy & Contiguous Gene Syndromes > Flashcards

Flashcards in 10/15 - Segmental Aneusomy & Contiguous Gene Syndromes Deck (11)
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1

Developmental delay

- minimal physical findings
- normal physical exam
- 5%-25% of children have genetic causes

2

MR - Intellectual delay

- IQ <70
- Degree of mental retardation and measured IQ and expected mental age as an adult in years

3

DiGeorge/VCF

- Deletion 22q.11
- Conotruncal heart defects
- Learning disabilities
- Psychiatric
- Speech/Language
- Dysmorphism

4

CMT1 Clinical Presentation

- Demyelinating peripheral neuropathy
- Foot deformities including pes cavus, hammer toes and foot drop
- Hyporeflexia/areflexia
- Claw hand deformities (in severe cases)

5

Newer chromosome tests

- microarrays genomic
- microarrays protein CHIP
- genome-wide array: CGH

6

Wolf-Hirschorn

- Deletion 4p
- 1/50,000
- 90% de novo
- Deletion of short arm chromosome 4 involving 4p16.3 to pter
- Critical region mapped to 4p16.3
- Some microdeletions seen only by FISH
- Death in infancy common can survive to adulthood
- "Greek warrior helmet"

7

Clinical characteristics of Wolf-Hirschorn

- IUGR with microcephaly
- Wideset eyes with "Greek warrior helmet" nasal bridge
- Colobomas
- Cleft lip/palate, fish-like mouth
- Midline scalp defects
- CHD, renal, and genital malformations
- Club feet
- Failure to thrive
- Profound MR and seizures

8

Cru Du Chat

- Deletion 5p
- One of the mot common human chromosome deletion syndromes
- 1/20,000 to 1/50,000 live births
- 85% de novo deletion - paternal origin 80%
- Remaining cases due to parental translocation involving 5p
- Patients noted to have mew-like cry (abnormal laryngeal development)

9

Clinical features of Cru Du Chat

- Microcephaly
- Round Face
- Hypertelorism
- Broad nasal bridge
- Low-set ears
- Down-slanting palpebral fissures
- Cardiac defects

10

Gene regions for Cru DU Chat

- Size of deletion may correlate with severity of phenotype
- Critical region for mew-like cry is 5p15.3
- Remaining clinical features mapped to 5p15.3
- Clinical features are less obvious with age
- Mental retardation less severe than previously thought

11

CGH+SNP Microarray

- Known/suspected consanguinity ~5% of families in USA
- Ancestral relatedness
- Families from Middle East, North Africa, and West Asia
- Isolated communities (Amish)
- Known/suspected incest
- Patients with recessive disorder - metabolic, rare syndromes
- Suspected imprinting disorder