The age at which symptoms appear may differ. In Crigler-Najjar type I syndrome, symptoms appear within the first few days of life, and most patients die in infancy. A few patients have survived into adolescence. In Crigler-Najjar type II syndrome, patients have jaundice during the first few years of life. Patients with Gilbert syndrome usually are diagnosed when aged 10-30 years.
Patients usually are anicteric, with normal life expectancy.
Hemolysis and mild icterus usually occurs at times of stress, starvation, and infection. The disease process appears at birth. Because the population affected by this disease overwhelmingly consists of infants, no clinical symptoms are reported. Patients may present with evidence of kernicterus. Physical examination is normal, except for jaundice.