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i am tasked with analyzing the transmission of a genetic disease through several...

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dgault11 | Honors

Posted July 20, 2013 at 1:51 PM via web

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i am tasked with analyzing the transmission of a genetic disease through several generations.  Males are indicated by square, females by circles. Individuals with the disease are colored solid black. Speculate on the genetic basis by which this disease is inherited. If any known carriers (those carrying the gene, but not manifesting symptoms of the disease) can be identified, list the individuals.

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tjbrewer | Elementary School Teacher | (Level 2) Associate Educator

Posted July 20, 2013 at 10:09 PM (Answer #1)

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The fact that parents without the condition have children with the condition means that it is a recessive gene.  Although 4/5 of those exhibiting the condition are men, the fact that Steven had the condition, but his father Ian did not proves it is NOT sex-specific. 

Since neither Martha nor Ian exhibited the condition, but their son Steven did, both Martha and Ian must be carriers.  Since Peri bore a son with the condition, but did not exhibit it himself, he and Leela both must be carriers.  Neither Donna nor Mickey exhibited the condition, but one of their children did, so they must be carriers.  Ben had the condition and Amy did not; however their daughter has the condition and can only inherit 1 of the 2 genes from her father, so Amy must be a carrier. 

The carriers are: Martha, Ian, Peri, Leela, Donna, Mickey, and Amy. 

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