Human Genetics and Disorders

RET mutation is responsible for increased risk of medullary thyroid cancer, as well as multiple endocrine neoplasia 2, in which pheochromocytoma and parathyroid adenoma also occur.

Gamma C deficiency is responsible for about 40% of cases of SCID and, together with JAK 3 deficiency, results in a T-B+NK- phenotype. It is also utilised by the receptors for IL-2, -4, -7, -9 and -21.

Cri-du-chat is caused by a deletion (the length of which may vary) on the short arm of chromosome 5. Multiple genes are missing, as a result of this deletion and each may contribute to the symptoms of the disorder. One of the deleted genes is TERT (telomerase reverse transcriptase).

Haemophilia is a genetic disorder that impairs the body's ability to control blood clotting. This causes prolonged bleeding because the blood doesn't clot properly. It does not cause blindness, loss of haemoglobin, or rheumatism.

Both statements are true, but R is not correct explanation of A. Cystic fibrosis (Mucoviscidosis) is an autosomal recessive genetic disorder that affects most critically the lungs and also the pancreas, liver, and intestine. It is caused by a point mutation in the gene cystic fibrosis transmembrane conductance regulator. Cystic fibrosis is characterised by abnormal transport of chloride and sodium across the epithelium in all exocrine tissues, leading to thick viscous secretions in the lungs, pancreas, liver, intestine, and reproductive tract and to an increased salt content in sweat gland secretions.

This is correct answer.

Ehlers-Danlos syndrome is characterised by hyperelasticity of skin, hyperextensebility of joints and fragility of skin and oral mucosa.

This is an correct answer because the serum alkaline phosphatase level may be increased in Paget's disease.

Hemophilia is an X-linked recessive genetic disorder, meaning the responsible genes are located on the X chromosome (one of the sex chromosomes). Males are more commonly affected because they have only one X chromosome. Autosomes, mitochondria, chloroplasts, and ribosomes are not the locations of hemophilia genes. This X-linked inheritance pattern explains why hemophilia predominantly affects males and can be carried by females.

Christmas disease is also known as haemophilia B.

Familial hypercholesterolemia results in defective apoB-100, E LDL receptor, a genetic condition that increases blood LDL cholesterol level.

Color blindness (red-green) is X-linked recessive, carried on the X chromosome and expressed more frequently in males (XY) who lack a second X chromosome to mask the trait. Pattern baldness, hypertrichosis, and skin color follow different inheritance patterns (autosomal or polygenic).

BRCA1 is indeed a tumor suppressor gene that maintains genomic integrity by preventing uncontrolled cell proliferation. The multifunctional BRCA1 protein participates in crucial cellular processes including DNA damage repair, ubiquitination, and transcriptional regulation. Mutations in this gene are well-established risk factors for hereditary breast, ovarian, and prostate cancers, making all three statements factually correct.

Fragile X Syndrome is caused by the loss of the FMR1 gene, which produces FMRP (Fragile X Mental Retardation Protein). FMRP acts as a translational regulator or 'brake' on protein synthesis in neurons, particularly at synapses. When FMRP is absent, there is excessive protein production leading to the cognitive and behavioral symptoms associated with Fragile X Syndrome. Note: The question has a typo - 'Foregile' should be 'Fragile'.

This is the correct option. Down syndrome is an example of inherited disease. It occurs when an individual has a full or partial extra copy of chromosome 21.