Comment on the following statements:

                                                                                            (10)

(i) Inborn error in metabolism like PKU are examples of monogenic disease.

PKU is single abnormal gene disorder or classic monogenic autosomal recessive disease that affects the the way the body breaks down protein.  PKU is caused by a mutation in a gene on chromosome 12 that codes for a protein called PAH (phenylalanine hydroxylase), an enzyme in the liver that breaks down the amino acid phenylalanine to tyrosine. Mutations in both copies of genes for PAH means that the enzyme is inactive or less efficient, and the concentration of phenylalanine in the body can buildup to toxic levels which can results in mental retardation, organ damage and sometimes, hyperphenylalanemia.

(ii) Thrombo embolism leads to heart attack.

Blood platelets normally do not adhere to smooth, healthy vessel linings. However, when platelets contact collagen at the site of vessel damage, they stick to the site and help promote the formation of blood clots. Furthermore, foam cells produce a potent clot promoter. Such an abnormal clot attached to a vessel wall is called a thrombus. The thrombus may enlarge gradually until it completely blocks the vessel at that site, or the continued flow of blood past the thrombus may break it loose. As it heads downstream, such a freely floating clot or embolous, may completely plug a smaller vessel. Thus, thrombo embolism, artherosclerosis can result in a gradual or sudden occlusion of a coronary vessel.

(iii) Oedema is one symptom that distinguishes between kwashiorkar and marasmus.

Kwashiorkar is characterized by peripheral edema which results from loss of fluid balance between hydrostatic and oncotic pressure across capillary blood vessels walls. Due to protein deficiency mainly low levels of albumin, they became intravascularly depleted. Subsequently, ADH increases, resulting in edema. Plasma renin also respond and cause sodium retention that contributes to edema. Marasmus is known as the wasting syndrome i.e., malnutrition without edema. Children have few silmilar symptoms but odema is the main distinguish factor between the two.

(iv) Cystic Fibrosis leads to insufficient hydration of lungs.

Normally, CFTR, a membrane protein and Cl- channel conducts the flow of Cl- ions out of the cell following their concentration gradient. The maintenance of electrical neutrality requires that Cl- ions accompany Na+. The transported ions are osmotically accompanied by H2O, thus maintaining the proper level of fluidity in secretion of lungs. Cystic fibrosis occurs due to the mutation in CFTR gene. And thus, the primary function of CFTR to maintain the hydration is obstructed, leading to insufficient hydration of lungs.