Lecture 2: Genetic Syndromes Flashcards Preview

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Flashcards in Lecture 2: Genetic Syndromes Deck (10)
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Prevalence of clefts: How many babies are born with clefts?

- 1:700 live births (over 5,000) in US each year
- between 1/5000 and 1/1000 for cleft lip and/or cleft
palate, and about 1/2500 for cleft palate alone


Prevalence of clefts: What groups are clefts more common?

more common among Asians (1:500) and certain groups of American Indians (1:300) than among Caucasians (1:800)


Prevalence of clefts: What group are clefts least common?

occur less frequently among African-Americans (1:2000)


Prevalence of clefts: What gender is more likely to have a cleft lip and cleft palate together (ratio)?

Cleft lip and cleft palate together are more common in boys - 3:2 ratio


Research findings

- Cleft palate may result from a combination of genetic and environmental factors (NIH, 1997)
- Scientists have identified not just a single gene, but a genetic circuit, that when broken, causes cleft palate in
newborn mice (NIH, 1997)
- Familial patterns and gene mapping involved in oral- facial clefts (Marazita, 1999)
- Gene ID’s shown to contribute to syndromic & non- syndromic CP/L


If neither parent has a cleft than the inheritance is either ________ or _________.

If neither parent has a cleft than the inheritance is probably either multifactorial or recessive and these are usually not distinguishable (multifactorial=combination of genes and environment)


What is the percentage of having another child with a cleft if the first child is born with a cleft?

Approximately 3-5% chance of having another similarly affected (risk increases more if have more than 1 affected child)


Multifactorial hereditary risks include:

- Recessive inheritance
- Autosomal dominant
- If it can be established that there are no other affected relatives, the risk to siblings (2.2%) is less than the overall risk (4%)
- Recurrence also influenced by how severe the cleft is: 5.6% for bilateral CP/L, 4.1% for unilateral CP/L and 2.6% for CL without CP


Syndromes are more common in ___________ than in ___________.

Syndromes are more common in CP alone than in CL with or without CP.


Clefts can occur with what syndromes?

- Stickler Syndrome
- Treacher Collins
- Pierre Robin
- DeGeorge (22-q deletion)
- Goldenhar
- Crouzon
*more listed in PPT