A disease caused by an autosomal primary non-disjunction is :a)Klinefelters Syndromeb)Turners Syndromec)Sickel Cell Anemiad)Downs SyndromeCorrect answer is option 'D'. Can you explain this answer?

Question

Answer

Down's syndrome in which non disjunction of 21 chromosome occurs

Answer

Answer

Down syndrome, a trisomy of chromosome 21,is the most common anomaly of chromosome number in humans. The majority of cases results from nondisjunction during maternal meiosis 1
Trisomy occurs in at least 0.3% of new borns and in nearly 25% of spontaneous absorptions.

Answer

Option (d) becoz-- >>
Down's syndrome is a genetic disorder caused when abnormal cell division results in extra genetic material from chromosome 21.

Answer

Autosomal primary non-disjunction refers to the failure of homologous chromosomes or sister chromatids to separate during cell division, resulting in an abnormal number of chromosomes in the resulting cells. This can lead to various genetic disorders, and one such disorder caused by autosomal primary non-disjunction is Down syndrome.

Down syndrome:
Down syndrome, also known as trisomy 21, is a genetic disorder caused by the presence of an extra copy of chromosome 21. Instead of the normal two copies, individuals with Down syndrome have three copies of chromosome 21 in their cells. This additional genetic material disrupts the normal development and causes a range of physical and intellectual disabilities.

Causes of Down syndrome:
The most common cause of Down syndrome is primary non-disjunction during the formation of the egg or sperm cells. During the process of meiosis, the chromosomes are supposed to separate properly, with each resulting cell receiving one copy of each chromosome. However, in cases of non-disjunction, the chromosomes fail to separate correctly, leading to an unequal distribution of chromosomes in the resulting cells.

Types of Down syndrome:
There are three types of Down syndrome:
1. Trisomy 21: This is the most common type, accounting for about 95% of all cases. It occurs when there is an extra copy of chromosome 21 in all cells of the body.
2. Translocation Down syndrome: This type occurs when a part of chromosome 21 breaks off and attaches to another chromosome, usually chromosome 14. While individuals with translocation Down syndrome have the usual two copies of chromosome 21, the extra genetic material can still cause the characteristic features of the syndrome.
3. Mosaic Down syndrome: This is the rarest form, accounting for about 1-2% of cases. In mosaic Down syndrome, only some cells have the extra copy of chromosome 21, while the remaining cells have the normal chromosomal complement. This results in a milder form of the disorder.

Clinical features of Down syndrome:
Down syndrome is associated with a range of physical and intellectual disabilities. Some of the common clinical features include:
- Intellectual disability and developmental delay
- Facial features such as almond-shaped eyes, flattened facial profile, and a protruding tongue
- Low muscle tone and poor muscle development
- Congenital heart defects
- Gastrointestinal abnormalities
- Increased risk of infections and certain medical conditions

Treatment and management:
There is no cure for Down syndrome, but early intervention and supportive care can help individuals with Down syndrome lead fulfilling lives. This may include therapies such as physical therapy, speech therapy, and occupational therapy. Additionally, regular medical check-ups and management of associated conditions are important for the overall well-being of individuals with Down syndrome.

In conclusion, Down syndrome is a genetic disorder caused by autosomal primary non-disjunction, resulting in an extra copy of chromosome 21. This leads to a range of physical and intellectual disabilities and requires lifelong management and support.

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