Term
Clues for Chromosomal Disorders |
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Definition
•Physical findings – dysmorphic features, growth retardation (prenatal and postnatal), multiple system involvement
•MR (especially with dysmorphology)
•History of recurrent spontaneous abortions, advanced maternal age, infertility
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Term
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Definition
- Caused by Trisomy 21
- upslanting palpebral fissures
- Single palmar crease
- Fifth finger clinodactyly
- Sandal gap with vertical plantar crease.
- epicanthal fold
- midfacial hypoplasia
- short nose with low nasal root and mildly
antiverted nares
Most Down s. children and some adults have a tongue which seems too large for the mouth.
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Term
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Definition
A prolonged phase in the female meiosis between synapsis/recombination and the two meiotic cell divisions |
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Term
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Definition
- Caused by Trisomy 18
- only 5-10% of babies survive the first year of life
- produces “prominent calcaneus,” as well as the extreme “rocker bottom feet.”
- characteristic fisting pattern
-prominent occiput
-MR
-CHD
-Kidney malformations
-Micrognathia
[image]
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Term
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Definition
- Caused by Trisomy 13
-polydactyly
- Cleft Lip/ Cleft Palate
- Rocker Bottom Feet
- Microcephaly
-Microphthalmia
[image] |
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Term
Trisomy 13 and holoprosencephaly |
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Definition
•Holoprosencephaly: failure of cleavage of the prosencephalon with deficits in midline facial development
•Causative gene: Sonic hedgehog, SHH
•Holoprosencephaly can be inherited as AD with variable expression (“the holoprosen -cephaly spectrum”)
•Found syndromically in trisomy 13
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Term
explanation for microdeletion syndromes: |
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Definition
- nonallelic homologous recombination
•A microdeletion syndrome occurs when a gene or a “critical region” for the syndrome is deleted.
•Genomic sequence data show these regions to be flanked by repeat sequences called LCRs, or “low copy repeats.”
•LCRs are blocks of DNA, 10-400 kb in length with ≥ 97% identity, but distinct from high-copy repeat sequences such as Sines, Lines, Alu, and satellite DNAs.
•LCRs make up 5-10% of the genome.
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Term
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Definition
-Criduchat syndrome, del 5p
- shows variance where deletion occurs
-WolfHirschhorn syndrome, del 4p
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Term
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Definition
-Prader-Willi s./Angelman s.: 15q11-q13
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Term
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Definition
-due to microdeletion of paternal chromosome
•MR; Moderate Severe hypotonia at birth
• Almondshaped eyes, narrow bitemporal diameter
• Short stature, small hands and feet
• Hypogonadism, microgenitalia
• Hyperphagia in childhood; (obesity)
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Term
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Definition
•Microcephaly, prognathism, large mouth with widely spaced teeth; openmouth expression
• Ataxia with puppetlike gait
• Severe MR, absence of language
• “Happy” disposition with inappropriate laughter
• Cause: absence or mutation E6AP ubiquitin ligase gene
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