Rudolph syndrome (red noses) and Elf syndrome (short stature, pointy ears) are c
ID: 174223 • Letter: R
Question
Rudolph syndrome (red noses) and Elf syndrome (short stature, pointy ears) are caused by defects at a locus on chromosome 7 that contains the Green and Xmas genes; the locus is known to be imprinted. Children with Rudolph syndrome typically have a deletion in the Xmas gene inherited from their father; children with Elf syndrome typically have a deletion in the Green gene inherited from their mother.a) Which gene is not maternally expressed?
Liam has Elf syndrome. FISH analysis identifies two chromosome 7s – no deletion was present. Further genetic testing was performed on DNA from Liam and both his parents and showed that Liam inherited two chromosome 7s from one parent and none from the other.
b) From which parent did Liam inherit his chromosome 7s?
Rudolph syndrome (red noses) and Elf syndrome (short stature, pointy ears) are caused by defects at a locus on chromosome 7 that contains the Green and Xmas genes; the locus is known to be imprinted. Children with Rudolph syndrome typically have a deletion in the Xmas gene inherited from their father; children with Elf syndrome typically have a deletion in the Green gene inherited from their mother.
a) Which gene is not maternally expressed?
Liam has Elf syndrome. FISH analysis identifies two chromosome 7s – no deletion was present. Further genetic testing was performed on DNA from Liam and both his parents and showed that Liam inherited two chromosome 7s from one parent and none from the other.
b) From which parent did Liam inherit his chromosome 7s?
Rudolph syndrome (red noses) and Elf syndrome (short stature, pointy ears) are caused by defects at a locus on chromosome 7 that contains the Green and Xmas genes; the locus is known to be imprinted. Children with Rudolph syndrome typically have a deletion in the Xmas gene inherited from their father; children with Elf syndrome typically have a deletion in the Green gene inherited from their mother.
a) Which gene is not maternally expressed?
Liam has Elf syndrome. FISH analysis identifies two chromosome 7s – no deletion was present. Further genetic testing was performed on DNA from Liam and both his parents and showed that Liam inherited two chromosome 7s from one parent and none from the other.
b) From which parent did Liam inherit his chromosome 7s?
Explanation / Answer
Both the genes are imprinted. Imprinted genes are silenced wherever they are found.
Rudolf syndrome is caused when Xmas gene inherited from father is deleted. This means that the 'Xmas' is imprinted in mother. Xmas is not expressed maternally.
On the other hand, Elf syndrome occurs when there is deletion in Green gene inherited from mother. That means that Green gene is imprinted in father.
c) Liam who has "Elf syndrome," has 7s with no deletion. This means that he has inherited both imprinted genes from father. There is non-disjunction of 7th chromosome in Liam's father.
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