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Christopher A. Jarrett, MD, Prasit
Nimityongskul, MD, Lewis D. Anderson, MD (deceased), University
of South Alabama, Mobile, AL; John R. Humphries, MD, Lafayette,
LA; Michael D. Goodlett, MD, Auburn, AL
Background: There are at least
five types of metaphyseal chondrodysplasia (MCD) of which
the Schmid type is the most common. Schmid type MCD is characterized
by sort stature (short limb type of dwarfism), coax vara,
bowed legs, and waddling gait. The skull, spine, and upper
extremities are minimally involved or normal. The primary
defect is believed to be in the metaphyseal part of the growth
plate, while the epiphysis is normal. MCD is an inherited
disorder and the Schmid type demonstrates an autosomal dominant
pattern of inheritance. There is little reporting of MCD in
the literature: the natural history and full spectrum of skeletal
manifestations are yet to be described.
Methods: A large single kindred
in central Alabama manifested this disorder and 42 affected
members of this family form the basis of this report. A pedigree
consisting of 135 members of this kindred is presented. Radiographic
and physical examination of all affected persons were studied
thoroughly. Interviews were performed on all members of the
pedigree.
Results: The mode of inheritance
is autosomal dominant with 42 individuals involved. Average
height is significantly less than that of the general population.
All affected individuals have coax vera with an average neck/shaft
angle of 106 degrees. Despite coax vera, premature osteoarthritis
of the hips is not a feature in this disorder. The knee was
in varus in 50% of these patients while one third stood in
genu valgum. Below the knees, there were no abnormalities
noted.
Conclusion: This is a relatively
large series of MCD. It has been limited to a single kindred
demonstrating the inheritance pattern and other classic features
of the Schmid type MCD including coax vara and short limb
dwarfism. Osteoarthritis was not a hallmark. Other findings
have never been documented in the literature.
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