This document discusses the biochemical and molecular basis of single gene or Mendelian disorders. It explains that these disorders can be caused by mutations that affect protein or gene product synthesis, including transcription, mRNA processing, and translation. It provides examples of how abnormal proteins can directly or indirectly influence phenotype. Specific mechanisms covered include enzyme defects, defects in membrane receptors and transport systems, alterations in non-enzyme proteins, and genetically determined adverse drug reactions. Marfan syndrome is used as an example of a disorder of structural proteins caused by a mutation in the FBN1 gene for fibrillin-1.

2. Genetic Disorders Biochemical and Molecular Basis of Single Gene (Mendelian) Disorders Dr. Shahab Riaz