IEM Flashcards
What are inborn errors of metabolism (IEM)?
Genetic disorders that block a metabolic pathway, leading to substrate buildup or deficiency.
How are IEMs inherited?
Autosomal recessive or X-linked recessive.
What do IEMs typically affect?
Metabolism of amino acids, proteins, carbohydrates, or lipids.
When do IEMs usually present?
In the newborn period—early screening is critical.
What are potential outcomes if IEMs go undiagnosed?
Irreversible cognitive impairment or early death.
What is PKU?
A metabolic disorder caused by a deficiency of the enzyme phenylalanine hydroxylase.
What happens when phenylalanine builds up in PKU?
Causes permanent brain damage and severe cognitive challenges.
How is PKU inherited?
Autosomal recessive.
How common is PKU?
About 1 in 10,000 births in the U.S.
What are signs of PKU?
Seizures, musty urine odor, atopic dermatitis.
How is PKU diagnosed?
Newborn screening done 2–3 days after birth.
What is the treatment for PKU?
Lifelong dietary restriction of phenylalanine (very strict and difficult).
What enzyme is missing in Tay-Sachs disease?
Hexosaminidase A, needed for lipid metabolism.
What happens when lipids accumulate in Tay-Sachs?
Leads to destruction of nerve cells, causing blindness and severe cognitive impairment.
How is Tay-Sachs inherited?
Autosomal recessive.
Who is most at risk for Tay-Sachs?
Individuals of Ashkenazi Jewish descent.
What are early signs of Tay-Sachs in infants?
Exaggerated Moro reflex, mild hypotonia.
What are late signs of Tay-Sachs?
Seizures, extreme hypotonia, blindness.
How is Tay-Sachs diagnosed prenatally?
Amniocentesis.
What is the prognosis for untreated Tay-Sachs?
Progressive decline leading to early death in childhood.
