Principles of Inheritance and Variation — BIOLOGY STD 12 Science — Question

Sickle Cell Anaemia and Phenyl ketonuria are the two autosomal genetic disorders as described below:
(i) Sickle Cell Anaemia: The red colour of Red blood cells (RBCs) is due to presence of a specific pigment named Haemoglobin which acts as carrier of oxygen and transports oxygen from respiratory surface to various cells of body. As blood becomes deficit of Haemoglobin. It loses it's ability to transport oxygen and this state is known as Annemia. Under low oxygen availability, molecular structure of haemoglobin is deformed so that RBCs become sickle shaped and unable to transport oxygen due to its deformed shaped this is why it is called sickle cell anaemia.
(ii) Phenylketonuria: This inborn error of metabolism is also inherited as the autosomal recessive trait caused due to lack of an enzyme phenylalanine hydroxylase that converts phenylalanine into tyrosine amino acid.
→ This phenylalanine, and its derivatives like phenylpyruvic acid therefore accumulate in blood and tissue, especially in cerebrospinal fluid (CSF) causing mental retardation and also get excreted in urine. This condition is known as Phenylketonuria.
→ The gene that controls the synthesis of enzymes is located on chromosome 12 (chromosome of C-group) in human being.
→ It has been seen that this disease occurs in about 1 in 18000 individuals.