Hereditary Tyrosinemia & Febrile Fits (Febrile Seizures)
Hereditary Tyrosinemia (HT)
A rare inherited metabolic disorder caused by defective breakdown of the amino acid tyrosine. The most common and severe form is Tyrosinemia type I.
Cause: Deficiency of the enzyme fumarylacetoacetate hydrolase (FAH)
Inheritance: Autosomal recessive
Main organs affected: Liver, kidneys, nervous system
Common features
Failure to thrive
Vomiting, diarrhea
Liver disease (hepatomegaly, liver failure)
Renal tubular dysfunction
Rickets
Risk of hepatocellular carcinoma
Episodes of acute metabolic crisis
Febrile Fits (Febrile Seizures)
Seizures that occur in young children (usually 6 months–5 years) triggered by fever, without underlying CNS infection.
Usually brief and generalized
Common in childhood
Often benign in otherwise healthy children
Connection between Hereditary Tyrosinemia and Febrile Fits
Children with hereditary tyrosinemia may develop seizures, including febrile seizures, due to:
Metabolic decompensation during infections
Accumulation of toxic metabolites (e.g., succinylacetone)
Electrolyte imbalances (hypoglycemia, hypocalcemia)
Liver dysfunction affecting glucose metabolism
Fever acting as a trigger during illness
⚠️ In HT, seizures are not always simple febrile seizures and may indicate a metabolic crisis, which is a medical emergency.
Key Management Points
Early diagnosis (newborn screening)
Treatment with nitisinone (NTBC)
Low-tyrosine and low-phenylalanine diet
Prompt treatment of infections and fever
Careful evaluation of any seizure episode
Take-home message:
Febrile fits in a child with hereditary tyrosinemia should never be assumed to be benign. They may signal metabolic instability and require urgent medical assessment.
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