Inborn errors of metabolism - class-X

Haemophilia is a classic example of an X-linked recessive disorder. It is transmitted via the X chromosome, making it a sex-linked trait.

Daughters inherit x chromosomes of father & mother respectively since one x chromosome masks the effect of another x chromosome, a daughter will only be colourblind if her mother is a carrier & father is colorblind.

Baldness is a sex-influenced trait, not a sex-limited trait. Sex-influenced traits are expressed in both sexes but are more common in one (like male pattern baldness).

Male pattern baldness is a sex-influenced trait. In males, it acts as a dominant trait, while in females, it acts as a recessive trait. If both parents are bald, the male child has a 100% chance of inheriting the allele and expressing the phenotype.

Haemophilia A, the most common form, is caused by a deficiency in clotting Factor VIII. Factor IX deficiency causes Haemophilia B.

• Haemophilia is genetically due to the presence of a $recessive$ sex-linked gene h, carried by the X chromosome. 
• A female becomes haemophilic only when both Its X chromosomes carry the gene $(XhXh)$. However, such females (mothers) generally die before birth because the combination of these two recessive alleles is lethal. A female having only one allele for haemophilia $(XX^h)$ appears normal because of the allele for normal blood clotting present on the other X-chromosome is dominant. Such females are known as carriers. 

The biochemical pathway for melanin synthesis involves the conversion of the amino acid tyrosine into dopa, then into dopaquinone, and finally into melanin.

Melanocytes, which produce melanin, are primarily located in the stratum germinativum (basal layer) of the epidermis.

Galactosemia is a metabolic disorder where the body cannot break down galactose. Avoiding milk and dairy products, which contain lactose (a source of galactose), prevents the accumulation of toxic metabolites.

Skin pigmentation is determined by the amount and type of melanin produced by specialized cells called melanocytes.

• Here, option (C) is correct as Galactosemia is metabolic genetic metabolic disorder due to deficiency of the enzyme uridyl transferase.
• While, carboxypeptidase is a protease enzyme that acts on 'C' terminal end of a protien or peptide.
• And, in pancreatic juice trypsin, amylase and lipase are present.