UGT1A1-related disorders in Bahrain: A genetic and clinical overview of Crigler-Najjar and Gilbert syndromes

Table 5 Summary of the main features of UGT1A1-related disorders

Main features	CNS-I	CNS-II	GS
Prevalence	Ultra-rare[26]	Unclear (no record)	Prevalent (8%-10%)[5,6,8,9]
UGT1A1 enzyme activity	0%[5]	< 10%[6]	10%-30%[9]
Age at presentation	Neonatal period[1,28]	Infancy or childhood[33]	Adolescence or adulthood[8]
Triggers of jaundice	None	Fasting, illness or stress[4,6]	Fasting, illness, or stress[5,8]
Clinical severity; unconjugated bilirubin range (µmol/L)	Severe[28,33]; 340-850[33]	Moderate[33]; 85-340[33]	Mild[8,33]; < 85[33]
Kernicterus risk	High[1,3,6,10]	Low[7]	None[5]
Medical therapy	Phototherapy[1,26], plasma phoresies[1,26], or liver transplantation[3,11]	Phenobarbital[33]	No treatment needed[5]
Outcome	Poor if not treated[1,3,10]	Good[33]	Excellent[6]

CNS: Crigler-Najjar syndrome; GS: Gilbert syndrome.