Question

A new syndrome is suspected to occur from de novo mutations and is also suspected to be autosomal dominant. However, a few cases have been found that indicate familial inheritance, but the parent shows no sign of the syndrome. Describe how you would use exome study to determine the DNA variant, and provide an explanation for the familial inheritance seen in the disorder.

Answer 1

Autosomal dominant inheritance means only a single copy of mutant gene is sufficient to cause the syndrome. In some cases the inheritance does not followed usual mendelian rules. There are several reasons for some individuals in a family not to show syndrome even they have the mutant allele.

Exome sequencing is a powerful tool to identify the mutant allele and it's variations. Faculty gene might undergo additional mutations which may affect the expression of the gene. Sequencing the exome from individuals in the family can give information on the type of genes or allele they have inherited and what are the sequence level variations.