What occurs due to the development of scar tissue?

Rationale:

A. Norepinephrine is released by the sympathetic nervous system during stress and primarily functions to increase heart rate, blood pressure, and alertness. It does not directly suppress inflammation.

B. Antidiuretic hormone regulates water retention in the kidneys to maintain fluid balance and blood pressure but does not significantly influence the inflammatory response.

C. Cortisol is a glucocorticoid hormone produced by the adrenal cortex in response to stress through activation of the hypothalamic-pituitary-adrenal (HPA) axis. It plays a central role in modulating the immune system by suppressing inflammation. Cortisol inhibits cytokine production, reduces leukocyte migration, decreases capillary permeability, and suppresses antibody production and T-cell activity. These effects prevent excessive tissue damage, conserve energy, and prioritize the body’s physiological resources for immediate stress adaptation. Chronic elevation of cortisol can lead to immunosuppression and increased susceptibility to infections.

D. Aldosterone is a mineralocorticoid hormone that regulates sodium and water reabsorption to maintain blood pressure. It does not have anti-inflammatory effects.

Rationale:

A. Sickle cell anemia is a monogenic disorder caused by a mutation in the HBB gene, which leads to abnormal hemoglobin S production. It follows a Mendelian autosomal recessive inheritance pattern, meaning a person must inherit two defective alleles (one from each parent) to express the disease. Environmental factors have little influence on whether the disease occurs, although they can affect disease severity.

B. Cystic fibrosis is caused by mutations in the CFTR gene and is also a single-gene autosomal recessive disorder. Disease expression is largely determined by genetics, although certain environmental factors, like respiratory infections, may influence symptoms and progression. It is not considered multifactorial because a single gene mutation is sufficient to cause the disorder.

C. Hemophilia A is an X-linked recessive disorder caused by a mutation in the factor VIII gene. Males are predominantly affected because they have only one X chromosome. This disorder follows a single-gene inheritance pattern, and while environmental factors can influence bleeding risk, the underlying cause is genetic alone.

D. Cleft palate is a classic example of a multifactorial disorder. It results from the interaction of multiple genes and environmental factors. Genetic predisposition may increase risk, but environmental influences—such as maternal smoking, alcohol use, certain medications, or nutritional deficiencies during pregnancy—can trigger or exacerbate the condition. Unlike single-gene disorders, multifactorial conditions do not follow simple Mendelian inheritance and often appear sporadically within families, though they may recur more frequently among relatives.