Types of Genetic Disorders

Genes are DNA segments that are carried in chromosomes. These genes help in the determination and expression of different human characteristics. These characteristics include hair color, height, weight, etc. These genes even play a role in your personality expression and behavior patterns. The most important aspect of genes is that they also have the ability to pass on diseases and disorders from the parent to the progeny.

The diseases or illness that arise due to abnormalities or discrepancies in genes or chromosomes are known as genetic disorders. Genes make up DNA, which is the basic unit of life. Any abnormalities within genes, changes the expression of the gene.

This change may lead to different genetic disorders. Sometimes, diseases or disorders are expressed due to two recessive genes coming together. Another factor that leads to genetic disorders are environmental factors like, exposure to radiation.

There are many rare genetic diseases that affect one in every thousands or maybe million individuals. Some inherited genetic diseases are known at birth, whereas some take time to get expressed. There are over 4,000 genetic disorders in humans, and scientists keep discovering new disorders with each passing day.

As this list of genetic disorders goes on increasing. Basically, there are four types of genetic disorders: single gene disorder, multi-factorial, chromosomal abnormalities, and mitochondrial mutations.

The single gene disorder, also known as Mendelian or monogenic disorder, occurs when the change or mutation takes place in only a single gene. The single gene disorders have high chances of being passed down from parent to children. These disorders include:

• Autosomal disorders: They arise from one abnormal gene coming from a single parent. For example, achondroplasia.
• Autosomal recessive: This is due to an abnormal gene from both parents. For example, sickle cell anemia and cystic fibrosis.

• X-Linked: These abnormalities are formed due to a single abnormal gene on the X chromosome. For example, hemophilia. There are X-linked dominant and X-linked recessive disorders. The X-linked dominant gene affects both male and female population. In X-linked recessive disorders, men are more commonly affected compared to females.

Y-Linked: In Y-linked disorders, the mutation or abnormality is seen only on the Y chromosome. As only the males inherit the Y chromosome, only boys will inherit the disorder from their fathers. For example, male infertility.

The multifactorial defect or polygenic problems are due to a combination of different factors like the effects of environment and lifestyle. Multi-factorial disorders include heart diseases, diabetes, hypertension, obesity, etc. The other environmental-related, multi-factorial disorders include:

• Asthma
• Autism
• Autoimmune diseases
• Cancer
• Ciliopathies
• Cleft palate
• Mental retardation

The mutations that occur in chromosomes can lead to changes in various genetic information. This leads to chromosomal abnormalities like aneuploidy, which includes Down syndrome, Turner syndrome, chromosomal sequence deletion, inversion of chromosomal sequence, and even translocation.

This follows a pattern of maternal inheritance as it is related to the mitochondrial DNA. Mitochondria is contributed only by the egg cells to the developing embryo. Thus, only mothers can pass mitochondria disorders to their children. For example, Leber's Hereditary Optic Neuropathy.

Thus, these were the different genetic disorder types in humans that may be expressed due to mutation.

Disclaimer: This story is for informative purposes only, and should not be used as a replacement for expert medical advice.