Explain why disorders caused by dominant alleles on autosomes are less common than those caused by recessive alleles on autosomes

Disorders caused by dominant alleles on autosomes are less common than those caused by recessive alleles on autosomes

Explanation:

Based on the Mendelian inheritance pattern,  

Autosomal dominant allele will affect a person if any one of the parent is affected.  

Autosomal recessive allele will affect a person only both the parents are carriers.

Autosomal diseases caused by dominant allele can occur in every generation and from that of recessive allele may not occur in every generation according to Mendel’s laws of inheritance.

However, many inherited disorders are more common due to recessive alleles. When only one copy of the DNA carried by one parent is passed, it is mostly harmless and may sometime get eliminated through natural selection process of evolution.  The chances of inheritance is only around 50% and children who do not inherit will neither develop any such disease or can pass the genes of the disease.

Although recessive, if both the parents are carrier, then the chances of inheritance doubles and hence recessive allele autosomal disorders occur more frequently. Inherited diseases like cystic fibrosis, sickle cell anemia caused by recessive allele is more common than diseases like Marfan’s syndrome caused by dominant allele.