Page 16 - Discover SPRING 2022

Riding for
TYLER
In many ways, Tyler Hanf is a typical 13-year-
old. He rides the bus to middle school, is a straight-A
student, loves to laugh and joke with his Dad, and
plays “FORTNITE” online with his friends.
The one thing that sets Tyler apart from most
other people is that he has Fibrodysplasia Ossificans
Progressiva, (FOP). FOP is a dominant genetic
disorder that occurs in about 1 in 1.6 million
births. Only somewhat more than 900 or so people
worldwide are known to have it. As such, it is often
not diagnosed until its effects become obvious. Even
then, it is so rare that it is not usually covered in
medical school curricula, so most doctors are not at
all familiar with it.
Although he had some early signs of something
not being quite right, it wasn’t until he was given a
routine vaccination for school that eventually led to
his diagnosis. His reaction to the medicine produced
a large hump on his shoulder, which at first his
parents thought might be a muscle tear. Doctors
were baffled by it, and after a long series of visits
to doctors and hospitals, a geneticist in Roanoke
noticed that his joints had not formed properly.
Although she had no idea what it was, she was
certain that there was something seriously wrong,
so she circulated his file among a number of her
colleagues, one of whom told her that it sounded
like FOP. Tyler was referred to a specialist in
Philadelphia, Dr. Kaplan, who is one of the very few
doctors who specialize in FOP.
FOP is caused by a mutation in the ACVR1
gene, and unlike recessive traits, such as blue eyes or
blonde hair, it only needs to be present on one gene
to manifest itself in the body. This gene triggers
14 Discover Smith Mountain Lake SPRING 2022
By Charles Alexander
the production of the ACVR1 protein, which
governs the growth and development of bone and
muscle tissue, including the gradual replacement of
cartilage by bone. It is this function that is abnormal
in FOP, which causes abnormal bone growth by
transforming muscle and connective tissue into
bone.
One of the unusual characteristics of FOP is
that its effects can vary significantly from person
to person. It doesn’t affect everyone in the same
way. In Tyler’s case, it is centered in his back, neck,
and arms. He is not capable of raising his arms, or
moving his neck or back. It may get progressively
worse over time, causing a further loss of mobility.
Some FOP patients have been known to live
relatively long lives, but there is no known way to
predict what will happen to any one individual.
In a normal body, the ACVR1 protein is
signaled as a reaction to injury, such as a broken leg.
The brain then instructs the affected area to produce
new bone tissue in order to mend the break. The
brains of people with FOP trigger the formation
of bone tissue without that input. Furthermore,
any injury that does occur could exacerbate the
condition, causing even more unwanted bone
growth.
Dr. Kaplan has specialized in FOP, but
according to Tyler’s father, Mike, “Unfortunately,
there’s not much he can do, other than monitor it.”
Treatment for Tyler’s condition is limited
mainly to pain management. Tyler is in puberty now,
which is normally an accelerated growth stage. His
body is trying to grow, but it’s inhibited by the FOP,
causing a great deal of pain. Dr. Kaplan treated him