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Kaplan Qbank USMLE



Author4 Posts
  #1

An infant is born with a unilateral cleft lip and palate.Previous studies have shown a concordance for this trait in Monozygotic twins of 0.40 and in Dizygotic twins of 0.04.Tha incidence of cleft lip and palate in the general population is 0.001.If these parents have a second child,the risk for unilateral cleft lip and palate in that infant is approxmimately:
a.75%
b.50%
c.25%
d.4%
e.0.1%

can someone plz explain how to work this out.

  #2

Cleft lip &/ palate is a multifactorial inherited disorder [genetic + environmental component]...
So the probability for second child is as that of a dizygotic twin which reflects the transmissibility of genetic component....
It must be 0.04 or 4%
DDDD...!!!

___________________
nothing in this world thats worth having,comes easy!!!- "SCRUBS"

  #3

if only the genetic component is involved(not multifactorial),then how will we calculate.
also,when do we use the monozygotic twins concordance?

thanks

  #4

If only genetic involved !!!- It depends on mode of inheritance...prevalence, penetrance, etc.
Refer to Hardy Weinberg equilibrium in Genetics notes.
GudLuck..!!!

___________________
nothing in this world thats worth having,comes easy!!!- "SCRUBS"







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