Question

What is a monogenic disorder?

Answer 1

Monogenic inheritance is a type of inheritance in which the trait in the progeny is determined by only one gene or allele. Polygenic inheritance includes inheritance of multiple genes or alleles. Monogenic inheritance follows Mendelian fashion of inheritance.

Complete answer:
Mendelian inheritance refers to patterns of inheritance that are specific to sexually reproducing organisms. Mendel described his results by explaining two laws of inheritance that gave the idea of dominant and recessive genes.
Monogenic disorders are caused mostly by an injury of a single gene. The phenotypic characters may depend to various extents on extra genetic variants in the same or other genes, epigenetic changes, and environmental factors. Although in the majority of organisms monogenic diseases are infrequent, together, they represent a high disease load in the population. Monogenic liver diseases start with the abnormality of a particular liver function and can further lead to either notable liver injury with secondary injury of other organs or no liver injury but injury of extrahepatic organs. In other cases, the liver and other organs may be affected by some different systemic disease.
Monogenic disorders are diseases caused by differences in a single gene and are basically recognized by their obvious familial inheritance patterns. Examples involved are sickle cell anemia, cystic fibrosis, Huntington disease, and Duchenne muscular dystrophy. Complex disorders are those in which multiple genes (Polygenic) play an important role, often together with environmental factors. These include many complex disorders such as cardiovascular disease, asthma, diabetes, and cancer susceptibility.

Note:
The inheritance of a trait ciphered in the mitochondrial genome is known as mitochondrial inheritance. As the mitochondria have some peculiar features, mitochondrial inheritance does not obey the basic rules of genetics. People with a mitochondrial disease may be male or female but they are always related in the maternal line and no male with the disease can transmit it to his children.