Pycnodysostosis is a rare, autosomal recessive disease characterized by Pycnodysostosis is a rare, autosomal recessive disease characterized by osteosclerosis, short stature, acroosteolysis of the distal phalanges, bone fragility,
clavicular dysplasia, and skull deformities with delayed closure of the sutures.
The disease is caused by a deficiency of the cysteine protease, cathepsin K,
located at 1q21, which is responsible for degradation of collagen type I and
other bone proteins.
Most common presentations of the patients with pycnodysostosis to pediatric
endocrinology clinics are short stature and/or frequent fractures. In our clinic,
genetically proven 9 patients with pycnodysostosis from 6 families were followed for 2 to 8 years. All of the index cases were presented with short stature
and, progressive loss of height SDS at follow-up was a common feature. Fractures of cranial bones, clavicles, long bones of lower extremity were noted in
7 of the 9 patients. Widely open anterior fontanel with delayed closure was
noted, as far as 11 years of age. One of the patient with delayed fontanel fusion had intracranial hemorrhage after mild trauma.
Acroosteolysis and osteosclerosis with dysmorphic features led to the diagnosis in all cases. X-rays revealed increased bone density with almost complete
obliteration of medullary cavity, batman sign and sandwich vertebrae appearance. Fundus examination revealed papilledema in one patient, needed one
decompression surgery of optic nerve and then, surgery for craniosynostosis
for continuing papilledema.
All of the patients had the symptoms of obstructive sleep apnea and, adenoidectomy had been performed in 6.
The detailed clinical and laboratory data with x-rays will be presented at the