GENETIC DISORDER

Genetic disorder is an abnormal condition in individual and it is inheritable viz., transmitted from generation to generation and caused by one or more abnormality in genome. Abnormality can occur in a single base of a gene to a gross structure of chromosomes such as addition or subtraction of a segment of gene or entire chromosome. This may also occur by mutation in germ cells due to environmental effect and new mutation also inheritable if occur in germ cell. Majority of genetic disorders are rare and affect one in several thousands or millions. Occurrence of genetic disorder increases due to marriage in close relatives i.e., “consanguineous marriages”. Genetic disorders can be classified into four broad group chromosomal disorders, mitochondrial disorders, single gene disorders and multi-factorial. Chromosomal disorder occur due to change in number and arrangement of chromosomes, mitochondrial disorders occur by change in mt-DNA and can show only maternal inheritance, single gene disorder occur by single defective gene and polygenic disorders called as multifactorial.

Genetic disorders may be inherited in four way, autosomal recessive, autosomal dominant, sex linked recessive, sex linked dominant. There are a lot of example of genetic disorder, such as sickle cell anemia inherited red blood cells disorder 1 million cases occur per year in India, thalassemia a inherited type of anemia occur due to abnormal haemoglobin about 3-4%(35-45 million) thalassemia carriers are in India, spinal muscular atrophy a genetic disorder that effect nerve cells of spinal cord have approximate frequency of 1 in 10000 babies, cystic fibrosis a respiratory disorder have a frequency 1/25 live birth but survival rate is very poor, haemophilia- A a blood clotting disorder have a frequency of 1/5000, Huntington chorea a neurodegenerative disorder having a frequency of 5-10/100000 in world, in most cases Huntington chorea inherited from parent but there are 10% cases due to new mutation also & are inheritable.

Genetic disorders are rare but deleterious for human health, generally this type of disorders are incurable. Proper care and rehabilitation is necessary for patients. Genetic counseling is important to avoid the situation.

Authors: Ms. Nargis K. and Mr. Azeem Ali