pycnodysostosis

Pycnodysostosis (from Greek: πυκνός (puknos) meaning 'dense', dys ('defective'), and ostosis ('condition of the bone')), is a lysosomal storage disease of the bone caused by a mutation in the gene that codes the enzyme cathepsin K.

Pycnodysostosis causes the bones to be abnormally dense (osteopetrosis); 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' (fontanelle) ...