Pycnodysostosis
(Pyknodysostosis)
Medically Reviewed by: William C. Shiel, Jr., MD, FACP, FACR
What is pycnodysostosis?
Pycnodysostosis is perhaps best known as the diagnosis given
retrospectively to the late 19th century French artist Henri de
Toulouse-Lautrec (portrayed by Jose Ferrer in the 1952 film
"Moulin
Rouge").
Pycnodysostosis is a genetic (inherited) disease of the bone.
Its
pattern of inheritance follows the classic rules of genetics
(see below).
Pycnodysostosis consistently causes short stature. The height
of adult
males with the disease is less than 150 cm (59 inches, or 4
feet 1 inch).
Adult females with pycnodysostosis are even shorter.
Pycnodysostosis causes the bones to be abnormally dense
(osteosclerosis); the last bones of the fingers (the distal
phalanges) to
be unusually short; and delays the normal closure of the
connections
(sutures) of the skull bones in infancy, so that the "soft
spot"
(the fontanel) on top of the head remains widely open.
Pycnodysostosis causes brittle bones which easily break
(fracture). The
bones in the legs and feet tend to fracture. The jaw and collar
bone
(clavicles) are also particularly prone to fractures.
The precise frequency of pycnodysostosis has never been
determined.
Pycnodysostosis can be classified in the large group of genetic
diseases
that are individually uncommon, but collectively important
because of the
sum of their numbers, their heavy impact upon affected
individuals, and
the equally heavy burden they place upon their families.
What is basis for the name of this disease?
The name for this disease was coined by the French physicians
Maroteaux
and Lamy in 1962. They described the disorder in a report
entitled "La
pycnodysostose." (They were not the only discoverers of
the disease.
Andren and colleagues independently described the condition in
1962.)
Maroteaux and Lamy put "pyknos," from the Greek
meaning "dense"
together with the compound word "dysostosis" meaning
abnormal
bone formation. The name "pycnodysostosis" was
designed to
convey the abnormally dense bone that is a hallmark of the
disease.
Although the original Maroteaux and Lamy spelling was with a
'c', it has
been written variably with a 'c' or a 'k'. Here we use the
original
spelling with a 'c'. No matter which way it is spelt, the name
has stuck
and is utilized worldwide today to designate this disease.
Next: What are the characteristics of pycnodysostosis? »
