Question

if a child was born with autosomal dominant disease, what can one conclude about the geneotype of the parent?

During the process of transcription of a gene, the wrong nucleotude is incorperated into the growing chain, if the error occurs in coding of a gene, how could this error affect protein synthesis from that gene?

thank you!

Answer 1

1. Dominant disorder can be expressed even in the heterozygous condition.
If a child is affected with an autosomal dominant disorder, one of the parent must be affected.
i.e. dominant disorder does not skip generations.

2. Errors in the coding region during transcription lead to various effects on the protein depending upon the type of mutation.
i. Missense mutation = Only one amino acid is affected
ii. Frame-shift mutation = The entire sequence downstream to the mutation is affected
iii. Non-sense mutation = A premature stop codon is generated leading to the formation of a truncated protein. Often, such transcripts are degraded by the Nonsense-mediated decay pathway
iv. Silent mutation = No change in the amino acid sequence