What is an autosomal disease?
What is an autosomal disease?
A disease caused by a gene located on a chromosome other than a sex chromosome (autosomal chromosome).
Autosomal recessive is one of several ways that a trait, disorder, or disease can be passed down through families. An autosomalrecessive disorder means two copies of an abnormal gene must be present in order for the disease or trait to develop.
The two autosomal genetic disorders are explained below.
1. Sickle cell Anaemia
It is an autosomal linked recessive disorder, which is caused by point mutation in the beta-globin chain of haemoglobin pigment of the blood. The disease is characterized by sickle shaped red blood cells, formed due to the mutant haemoglobin molecule.The disease is controlled by HbA and HbS allele.
The homozygous individuals with genotype, HbS HbS, show the symptoms of this disease while the heterozygous individuals with genotype, HbA HbS, are not affected. However, they act as carriers of the disease.
Symptoms
Rapid heart rate, breathlessness, delayed growth and puberty, jaundice, weakness, fever, excessive thirst, chest pain, and decreased fertility are the major symptoms of sickle cell anaemia disease.
2. Huntingtons disease or Huntingtons chorea
It is a dominant autosomal inherited disorder in which muscle and mental deterioration occurs. There is gradual loss of motor control resulting in uncontrollable shaking and dance like movements (chorea). Life expectancy averages 15 years from the onset of symptoms. This disorder does not occur till the age of 25 to 55. The defective gene is dominant autosomal, located on chromosome 4. This defective gene has 42 -100 repeats of CAG instead of 10-34 repeats in normal gene. The frequency of this disorder is 1 in 10000 to 1 in 20000.
Symptoms
The brain shrinks between 20-30% in size followed by slurring of speech, loss of memory and hallucinations.
Autosomal recessive is one of several ways that a trait, disorder, or disease can be passed down through families. An autosomalrecessive disorder means two copies of an abnormal gene must be present in order for the disease or trait to develop.
The two autosomal genetic disorders are explained below.
1. Sickle cell Anaemia
It is an autosomal linked recessive disorder, which is caused by point mutation in the beta-globin chain of haemoglobin pigment of the blood. The disease is characterized by sickle shaped red blood cells, formed due to the mutant haemoglobin molecule.The disease is controlled by HbA and HbS allele.
The homozygous individuals with genotype, HbS HbS, show the symptoms of this disease while the heterozygous individuals with genotype, HbA HbS, are not affected. However, they act as carriers of the disease.
Symptoms
Rapid heart rate, breathlessness, delayed growth and puberty, jaundice, weakness, fever, excessive thirst, chest pain, and decreased fertility are the major symptoms of sickle cell anaemia disease.
2. Huntingtons disease or Huntingtons chorea
It is a dominant autosomal inherited disorder in which muscle and mental deterioration occurs. There is gradual loss of motor control resulting in uncontrollable shaking and dance like movements (chorea). Life expectancy averages 15 years from the onset of symptoms. This disorder does not occur till the age of 25 to 55. The defective gene is dominant autosomal, located on chromosome 4. This defective gene has 42 -100 repeats of CAG instead of 10-34 repeats in normal gene. The frequency of this disorder is 1 in 10000 to 1 in 20000.
Symptoms
The brain shrinks between 20-30% in size followed by slurring of speech, loss of memory and hallucinations.
