Скачать или смотреть Crigler-Najjar Syndrome Type I 🧬 Biochemistry & Pediatrics | USMLE Step 1 & Step 2 CK

📌𝗝𝗼𝗶𝗻 𝗢𝘂𝗿 𝗧𝗲𝗹𝗲𝗴𝗿𝗮𝗺 𝗖𝗵𝗮𝗻𝗻𝗲𝗹 𝗛𝗲𝗿𝗲:- https://t.me/bhanuprakashdr
📌 𝐅𝐨𝐥𝐥𝐨𝐰 𝐨𝐧 𝐈𝐧𝐬𝐭𝐚𝐠𝐫𝐚𝐦:-   / drgbhanuprakash  
📌𝗦𝘂𝗯𝘀𝗰𝗿𝗶𝗯𝗲 𝗧𝗼 𝗠𝘆 𝗠𝗮𝗶𝗹𝗶𝗻𝗴 𝗟𝗶𝘀𝘁:- https://linktr.ee/DrGBhanuprakash

Crigler-Najjar Syndrome Type I 🧬 Biochemistry & Pediatrics | USMLE Step 1 & Step 2 CK

Crigler-Najjar Syndrome Type I is a rare, autosomal recessive disorder of bilirubin metabolism caused by a complete absence of the enzyme UDP-glucuronosyltransferase (UGT1A1), which is essential for conjugating bilirubin in the liver. As a result, affected individuals are unable to convert lipid-soluble unconjugated bilirubin into its water-soluble conjugated form, leading to severe, persistent unconjugated hyperbilirubinemia from birth. This is a high-yield metabolic disorder tested in USMLE Step 1 (Biochemistry) and Step 2 CK (Pediatrics and Internal Medicine).

Clinically, Crigler-Najjar Type I presents in the neonatal period with jaundice, icterus, and rapidly rising total bilirubin levels, often exceeding 20–50 mg/dL, with the unconjugated (indirect) fraction predominating. Because unconjugated bilirubin is lipid-soluble, it crosses the blood-brain barrier and can deposit in basal ganglia and brainstem nuclei, causing kernicterus—a life-threatening condition characterized by hypotonia, lethargy, seizures, opisthotonus, and irreversible neurologic damage. Without treatment, this condition is often fatal in infancy or early childhood.

Diagnosis is based on:

Persistent unconjugated hyperbilirubinemia

Normal liver enzymes and no hemolysis

Negative Coombs test

Genetic testing for UGT1A1 mutations

Absent UGT activity in liver biopsy (if performed)

Treatment is challenging because the enzyme is completely absent. The mainstay is intensive phototherapy, which converts unconjugated bilirubin into water-soluble isomers that can be excreted without conjugation. Exchange transfusions may be necessary in acute settings to reduce bilirubin levels and prevent kernicterus. Phenobarbital, which induces UGT activity, is ineffective in Type I (in contrast to Type II, which has partial enzyme activity). Ultimately, liver transplantation is the only definitive treatment and can be curative.

On USMLE, it is essential to distinguish Crigler-Najjar Type I from:

Crigler-Najjar Type II (partial UGT activity, responds to phenobarbital)
Gilbert Syndrome (mild, intermittent elevation of unconjugated bilirubin)
Dubin-Johnson & Rotor syndromes (conjugated hyperbilirubinemia)


#CriglerNajjarSyndrome #UnconjugatedHyperbilirubinemia #UGTDeficiency #Kernicterus #NeonatalJaundice #Phototherapy #LiverTransplant #USMLEStep1 #USMLEStep2CK #PediatricHepatology #BiochemistryBuzzwords #InheritedMetabolicDisorder #UGT1A1 #MedicalEducation #WhiteboardMedicine #Step1Review #Step2Review #MCQPrep #USMLEBuzzwords #GilbertVsCrigler #PhenobarbitalResistance #NeonatalHepatitis #USMLE2025 #DrGBhanuPrakash