**Question:** False about Criggler Najjar syndrome II

A. It is a rare genetic disorder
B. It is characterized by prolonged jaundice after birth
C. It is caused by a deficiency in the gamma-glutamyltranspeptidase enzyme
D. It is usually diagnosed in the first week of life

**Core Concept:** Criggler Najjar syndrome II (CN II) is a rare, autosomal recessive disorder that leads to severe neonatal hyperbilirubinemia (excessive jaundice) due to a deficiency in the gamma-glutamyltranspeptidase (GGT) enzyme. GGT is an enzyme that plays a crucial role in the process of bilirubin excretion, and its deficiency leads to elevated bilirubin levels in the blood. The disorder can be confused with Criggler Najjar syndrome I, but the later is characterized by absence of GGT.

**Why the Correct Answer is Right:** Criggler Najjar syndrome II is characterized by prolonged jaundice after birth (D), which is a key differentiating factor from syndrome I. Unlike CN I, CN II is not diagnosed within the first week of life but typically presents between the first and third week after birth. This delay in diagnosis is due to the presence of GGT enzyme activity in CN II patients, which helps in excreting bilirubin from the body. However, the deficiency in the enzyme is responsible for the prolonged jaundice.

**Why Each Wrong Option is Incorrect:**

A. Rarity is a general characteristic of genetic disorders, not specific to CN II.
B. Prolonged jaundice is present in CN II, but the misconception is that it is caused by prolonged jaundice itself. In CN II, the prolonged jaundice is a result of the deficiency in GGT enzyme, which is responsible for excreting bilirubin from the body.
C. Gamma-glutamyltranspeptidase (GGT) is not the deficiency that causes the prolonged jaundice in CN II. GGT is present in CN II patients, which is why CN I is a better comparison for CN II.

**Clinical Pearl:** A neonatal screening test for bilirubin levels is crucial in distinguishing between Crigglers Najjar syndromes I and II. CN II presents between the first and third week of life with prolonged jaundice, while CN I presents within the first week of life with no GGT activity.

**Correct Answer:** C. Gamma-glutamyltranspeptidase (GGT) is not the deficiency that causes the prolonged jaundice in CN II. GGT is present in CN II patients, which is why CN I is a better comparison for CN II. The key difference between the two is the presence of GGT activity, which is absent in CN I and present in CN II.