A girl complaints of acute abdominal pain on and off with tingling sensation of limbs. She had a history of eating paint from the wall of newly built house. Which of the following enzyme deficiency will be the cause of her condition?
(A) ALA dehydratase (B) ALA synthase (C) Coproporphyrinogen synthase (D) Heme synthase
(A) Answer- A. ALA dehydrataseALA dehydratase is a zinc-containing enzyme and is sensitive to inhibition by lead (present in the paints). High levels of lead can affect heme metabolism by combining with SH groups in enzymes such as ferrochelatase and ALA dehydratase.The most common presentation of lead poisoning is an encephalopathy.Laboratory investigation can reveal a microcytic hypochromic anemia with basophilic stippling of erythrocytes, an elevated serum lead level, and an elevated serum coproporplryrin level. A 24-h urine collection demonstrates elevated levels of lead excretion.The neuropathy is characterized by an insidious and progressive onset of weakness usually beginning in the arms, in paicular involving the wrist and finger extensors.