Human Genetic Disorders

Genetic disorders, as we know, are caused by an abnormality in the gene or chromosome patterns in a human. There are some disorders that are caused mainly due to genetic issues and others that are caused due to a combination of genetic and environmental conditions. There are various kinds of disorders related to the genetic structure and are classified as single gene disorders and multifactorial or polygenic disorders. The single gene disorders are also sub classified as autosomal dominant, autosomal recessive, X-linked dominant, X-linked recessive, Y-linked and mitochondrial. There has been a fair amount of study that has been done on each of these disorders of the genes and each type of disorder has been studied in detail by researchers.

Since the diseases related to these are genetic in nature, there are times that some of the disorders that surface are extremely specific and individualistic in nature. These conditions are called rare genetic diseases. A genetic disorder can also be common and some of the conditions that you may have come across may actually have their origins in the gene structure and you may just not know about the real cause.

Genetic disorder that arises from a single gene that has undergone mutation is called single gene disorders. Sometimes these conditions can occur even when the specific condition does not exist in wither parent. This can mainly happen when the specific gene in question is recessive in the parent but becomes dominant in the off spring. The classification of recessive and dominant genes is not cast in stone and there are times when differences have been observed. These have also been studied at length.

If you see a list of genetic disorders, you will realize that there are many that you may be familiar with. These are dependent on whether the X gene is dominant or recessive for that specific trait that the gene carries. Some X linked disorders have been noted to be more prevalent in men, especially in the case where the mother has one X chromosome that is recessive in nature.

Some of the human genetic disorders are mentioned here. Autosomal dominant – hereditary nonpolyposis colorectal cancer, Huntington’s disease, Marfan Syndrome and Neurofibromatosis 1. Autosomal recessive – cystic fibrosis, spinal muscular atrophy, dry earwax and sickle-cell disease. X-linked dominant – Rett syndrome, incontinentia pigmenti and aircardi syndrome. X-linked recessive – Hemophilia A, red-green color blindness and muscular dystrophy. Y-linked – Male infertility. Mitochondrial – human mitochondrial genetics, and Leber’s hereditary optic neuropathy. The list is by no means exhaustive. It covers a fair number of disorders that humans face that are related to single gene issues.
Other disorders that are related to the gen structure can be more complex and therefore multifactorial in nature. These conditions are associated with various combinations of genes and are therefore difficult to study. While these disorders are also hereditary, they are not easily traced back as the single gene disorders. Due to this specific characteristic, it is difficult to ascertain the level of risk that an individual has based on family history and the past. Some of these have genetic and environmental causes as well that ultimately result in the disease surfacing. Some of the polygenic disorders are asthma, autism, cancers, cleft palate, metal retardation, diabetes, auto immune diseases like multiple sclerosis and more. While we have come a long way with genetics as a study, there are still many genetic disorders that need to be understood and studied.