Genetic Disorders and Infertility

The basic physical and functional unit of inheritance is “the gene.” A gene comprises the information required to identify characteristics. Genes are arranged (one after another) into structures referred to as chromosomes.

A chromosome is composed of a single, extensive DNA molecule. Hundreds to thousands of genes are present in each chromosome. Every normal human cell contains 23 pairs of chromosomes for a total of 46 chromosomes. The exception exists for egg and sperm cells.

One of the 23 chromosome pairs is known as the sex chromosome, while the other 22 pairs are called autosomes. Usually, an individual has two sex chromosomes. A normal female has two X chromosomes (XX), while a male has one X and one Y chromosome (XY).

A genetic disorder refers to a condition that results from an alteration or variation within a gene/genes. A gene variant is inherited from either one or both parents.

Genetic disorders can be categorized depending on their mode of inheritance from one generation to the next.

·       Single-gene/monogenic disorders refer to a specific disease or disorder resulting from a change/variant in a particular gene. For example, Sickle Cell Anaemia or Thalassaemia result from variants in the HBB gene

·       Chromosomal disorders involve alterations (change in number or structure) affecting entire chromosome(s) or part(s) of chromosomes. For example, Down Syndrome results from an extra copy of chromosome 21.

·       Complex or multifactorial disorders result from combined genetic modifications in multiple genes and may be influenced by a person’s lifestyle and environmental factors. For example, diabetes, heart problems, obesity, blood pressure, Alzheimer’s, and cancers. 

• Multifactorial inheritance may result in some genetic problems. This includes one or more genes along with exposure to factors like the environment.
• There is no single genetic cause found in certain medical conditions like diabetes, heart problems, asthma, obesity, or cancers.
• They are often linked to the effects of multiple genes together with certain environmental or lifestyle factors. Hence, it is quite complex to establish an individual’s risk of inheriting these disorders.