What is Propionic Acidemia (PA)?
Propionic Acidemia (PA) is a rare disorder that is inherited from both parents. Neither parent shows symptoms, but both carry a defective gene responsible for this disorder. It takes two faulty genes to cause PA.
Individuals with PA cannot break down parts of protein and some types of fat due to either a missing or a non-functioning enzyme called PCC. This inability causes a build-up of harmful substances which can cause damage to the person’s heart, liver, brain, and bones. The result can be seizures, delays to normal development like walking and talking, and other health problems. During times of illness the individual with PA may need to be hospitalized to prevent breakdown of proteins within his/her body.
What are the symptoms of Propionic Acidemia?
Symptoms will present themselves within days of birth (acute
onset) or later in childhood (late onset) depending on the
severity of the disorder. Symptoms may include: refusal to
eat, poor sucking ability, vomiting, dehydration, lethargy
(excessively tired or sluggish), acidosis (excess acid in
the blood), and hyperammonemia (excess ammonia in the blood)
If not treated, mental impairment, coma and death can follow.
How is Propionic Acidemia diagnosed?
Most states provide comprehensive newborn screening (CNBS)
for Propionic Acidemia. Potential late onset cases can be
identified using this type of testing. Such cases are verified
through additional blood and urine tests. Diagnosis of acute
onset cases is typically made in the intensive care unit when
newborns go into a metabolic crisis within the first few days
If the baby isn’t screened at birth, late onset cases
may present themselves throughout the first few months of
life with failure to thrive, vomiting, trouble feeding, and/or
low muscle tone. If the symptoms aren’t addressed, late
onset cases are usually diagnosed in the ER after a traumatic
metabolic crisis. Early detection and treatment of propionic
acidemia can potentially improve the prognosis of the affected
What is comprehensive newborn screening?
Comprehensive newborn screening is a simple blood test where
a heel prick is performed on the baby to get a few drops of
blood. The test should be done 24-48 hours after birth. The
test is used to identify many life-threatening genetic disorders
including Propionic Acidemia. Each state determines which
disorders are included in their newborn screening panel. If
your state does not screen for Propionic Acidemia, you can
have your child tested through an independent laboratory.
(See Sites of Interest)
How do you get PA?
The gene defect for PA is an autosomal recessive genetic
trait that is unknowingly passed down from generation to generation.
Autosomal means that the condition can affect males and females. Recessive means that the person with the disorder has two copies of the faulty gene (one from the mother and one from the father). This faulty gene only emerges when two carriers have children
together and both pass it to their offspring. A carrier has one functioning gene and one faulty gene. For each pregnancy
of two such carriers, there is a 25% chance that the child
will be born with the disease and a 50% chance the child will
be a carrier for the gene defect.
PA occurs in approximately 1 in 50,000 live births in the
What is the treatment?
Every day an individual with propionic acidemia walks a metabolic tightrope
of getting enough protein for normal growth and development
and getting too much protein causing instability. Dietary
restriction of total protein, the four offending amino acids
(valine, isoleucine, methionine and threonine), and odd-chained
fats is the treatment. This is given through a carefully calculated
metabolic formula determined by your doctor and nutritionist.
The diet is also supplemented with levocarnitine to help remove
toxic metabolites. Although some PA children learn to eat,
most require gastronomy tube feedings since they have little
to no appetite and food aversions.
Is PA contagious?
No, it is a genetic disorder.
Can an individual outgrow Propionic Acidemia?
No, PA is caused by a genetic defect. This is why it is so
important to fund PA research that will develop a true cure
for this disorder.
What complicates PA?
Illness (cold, flu, GI bugs, viruses, etc.), stress, dehydration,
lack of calories and constipation can cause metabolic instability.
During these times, caregivers will want to speak with physicians
about further restrictions in protein or a trip to the ER
for IV hydration and monitoring. Some children with PA are
more prone to elevated ammonia levels, pancreatitis and cardiomyopathy.
What gene and chromosome causes PA?
Propionic acidemia (PA) is caused by defects in either the PCCA (chromosome 13q32) or PCCB (chromosome 3q21-q22) genes.
Is Propionic Acidemia called anything else?
Yes, you may find it under:
Hyperglycinemia with Ketoacidosis and Lactic Acidosis, Propionic Type;
Ketotic Glycinemia; PCC Deficiency; Propionyl CoA Carboxylase Deficiency or Propionic Aciduria
Another great Fact Sheet by STAR-G: PA Fact Sheet
Propionic Acidemia Foundation
Phone: Toll Free 1-877-720-2192
1963 McCraren Rd.
Highland Park, IL 60035