Concept explainers
In a family with one autistic child the risk for another affected child is approximately 25 percent. This is the same level of risk that a couple who are each heterozygous for a recessive allele will have an affected child. What are the similarities and differences in these two situations?
To determine: The similarities and differences between the cases-one autistic child in family raising the 25 % risk for another to develop autism and the heterozygous couple having an affected child.
Introduction: Autism is a severe developmental disorder in which the individual has impaired communication. The person faces challenges with social interaction, has obsessive interests and repetitive behaviors. The family which has one autistic child, the risk for another affected child gets raised by 25%. This is considered the same level of risk that a couple, both heterozygous for the recessive allele would have as they give rise to an affected child.
Explanation of Solution
The similarity between the two situations is that both of them give rise to autism affected individual. The development of autism can be both genetic and environmental. In the case, where the presence of one autistic child in the family raises the risk by 25% for the second child to be affected with the disease, shows the environmental causes of the disorder. On the other hand, the presence of two heterozygous (for recessive allele) parents to produce an affected child, shows the genetic cause of disease.
The differences between the two situations are as follows:
No. | Characteristics | A family with already an autistic child | A couple heterozygous for recessive allele |
1. | Cause of disease | The probability of the second child to have the disease shows the non-genetic cause of disease. | The probability of a child to develop autism from heterozygous parents shows a genetic form of the disease. |
2. | Proposed mechanism for development of disease | The nongenetic cause of autism is neuroinflammation, where there is an abnormality in the white matter. The white matter acts as a wiring tissue for connecting areas of the brain. | The genetic cause of autism occurs when both the parents have one recessive allele for the disease. As a result, when an individual has the presence of both the recessive alleles, autism is developed. |
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