Page 294 - Binder2

Case 1: A Child with Phenylketonuria, Treated Through
a Plant-Based Enzyme

Phenylketonuria (PKU) is a rare genetic disorder that
renders the body unable to break down phenylalanine, an
amino acid found in most proteins. Left unmanaged, it
leads to cognitive impairment, neurological damage, and
developmental delays. The standard treatment is a lifetime
of dietary restriction—avoiding nearly all protein-
containing foods—and enzyme replacement therapy, which
often comes with high cost and immune complications.

In one compassionate-use case, a young patient received an
oral formulation of phenylalanine ammonia-lyase (PAL),
the key enzyme that their body couldn’t produce. But
instead of injecting it—or purifying it from bacteria in a
lab—this PAL came from lettuce.

The gene encoding the enzyme was inserted into
chloroplasts of romaine lettuce, which was then grown,
harvested, freeze-dried, and delivered as oral capsules. The
patient took the capsules with meals, and the plant-
encapsulated enzyme began breaking down phenylalanine
in the gut—just as nature would have done.

Blood levels stabilized. Dietary flexibility improved. And
perhaps most important: the treatment was well-tolerated,
with no immune complications or adverse events. For this
child and their family, the burden of disease softened—not
through a breakthrough molecule, but through a new way
of delivering a known one.

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