UPSC-CMS 2018 — Biochemistry

Question 1: Which one of the following conditions can be screened during neonatal screening by biochemical tests?

• A. Congenital dislocation of hip
• B. Congenital rubella
• C. Chromosomal abnormalities
• D. Congenital hypothyroidism (Correct Answer)

Explanation: ***Congenital hypothyroidism*** - **Neonatal screening** for congenital hypothyroidism is a standard practice, using biochemical tests to measure **thyroid-stimulating hormone (TSH)** and **thyroxine (T4)** levels in dried blood spots. - Early detection and treatment prevent severe **intellectual disability** and developmental delays caused by thyroid hormone deficiency. *Congenital dislocation of hip* - This condition is primarily screened through **physical examination** (e.g., Ortolani and Barlow maneuvers) and imaging (e.g., ultrasound), not biochemical tests. - It involves a structural abnormality of the hip joint, not a metabolic or biochemical disorder. *Congenital rubella* - Diagnosis of congenital rubella involves detecting **rubella-specific IgM antibodies** or viral RNA, which are immunological/virological tests, not typical biochemical screening. - This is an infectious disease, not an inborn error of metabolism screened biochemically. *Chromosomal abnormalities* - Conditions like Down syndrome (Trisomy 21) are detected through **karyotyping** or **genetic tests**, which examine the number and structure of chromosomes. - While some biochemical markers are used in prenatal screening for chromosomal abnormalities (e.g., quad screen), direct neonatal screening for chromosomal abnormalities is not performed via general biochemical tests.