Consider the following statements : Statement I: Signs of thalassemia major usually develop after 6 months of age. Statement II: This is the time when haemoglobin synthesis switches from haemo-globin F to haemoglobin A. Which one of the following is correct in respect of the above statements?
Thalassemia Major: Signs and Haemoglobin Synthesis Timing
Statement I Analysis: Signs of severe thalassemia, known as thalassemia major, typically manifest after the first few months of life, usually around 6 months of age. This is because infants initially rely on fetal hemoglobin ($HbF$), which masks the condition's severity at birth.
Statement II Analysis: Following birth, there is a natural physiological transition where the synthesis of fetal hemoglobin ($HbF$) decreases, and the production of adult hemoglobin ($HbA$) increases. This shift is normally well underway by 6 months of age and complete within the first year.
Relationship Explanation: The onset of symptoms in thalassemia major is directly linked to this switch. In thalassemia major, the body cannot produce adequate amounts of adult hemoglobin ($HbA$) due to genetic defects. As the protective fetal hemoglobin ($HbF$) levels naturally decline around 6 months, the severe deficiency in $HbA$ production becomes apparent, leading to the characteristic signs of severe anemia. Therefore, the timing of the hemoglobin switch (Statement II) correctly explains why the clinical signs of thalassemia major (Statement I) typically appear after 6 months of age.
Based on the analysis, both statements are correct, and Statement II provides the accurate explanation for Statement I.
Important Questions from Genetic Disorders & Public Health
- Which one of the following conditions is NOT inborn error of metabolism?
- Amniocentesis is called for in all of the following circumstances EXCEPT:
- Consider the following pairs of genetic diseases that show Mendelian inheritance. Each of the following pairs represents a genetic disease and it has been matched with a type of inheritance :How many of the pairs given above are correctly matched?
1 Cystic fibrosis Autosomal recessive 2 Huntington's chorea Autosomal dominant 3 Marfan's syndrome Recessive sex-linked - Cystic fibrosis involves which of the following organs?
1. Lungs
2. Liver
3. Pancreas
4. Kidney
Select the correct answer using the code given below. - Which of the following statements are correct in respect of haemophilia?
1. It is hereditary bleeding disorder.
2. It has a higher incidence among Asians.
3. It affects females occasionally and mildly.
Select the correct answer using the code given below.
