Orphanet:
58
Spondylo-megaepiphyseal-metaphyseal dysplasia is a rare, genetic primary bone displasia characterized by disproportionate short stature with short, stiff neck and trunk and relatively long limbs, fingers and toes (which may present flexion contractures), severe vertebral body ossification delay (with frequent kyknodysostosis), markedly enlarged round epiphyses of the long bones, absent ossification of pubic bones and multiple pseudoepiphyses of the short tubular bones in hands and feet. Neurological manifestations resulting from cervical spine instability may be observed.
MalaCards based summary:
Spondylo-Megaepiphyseal-Metaphyseal Dysplasia, also known as smmd, is related to pyle disease and metaphyseal dysplasia. An important gene associated with Spondylo-Megaepiphyseal-Metaphyseal Dysplasia is NKX3-2 (NK3 Homeobox 2). Affiliated tissues include bone, and related phenotypes are macrocephaly and short neck
OMIM®:
57
Spondylo-megaepiphyseal-metaphyseal dysplasia is a rare autosomal recessive skeletal dysplasia characterized by disproportionate short stature with a short and stiff neck and trunk; relatively long limbs that may show flexion contractures of the distal joints; delayed and impaired ossification of the vertebral bodies and the presence of large epiphyseal ossification centers and wide growth plates in the long tubular bones; and numerous pseudoepiphyses of the short tubular bones in hands and feet (summary by Hellemans et al., 2009). (613330) (Updated 08-Dec-2022)
UniProtKB/Swiss-Prot:
73
A skeletal dysplasia characterized by disproportionate short stature with a short and stiff neck and trunk, relatively long limbs that may show flexion contractures of the distal joints, delayed and impaired ossification of the vertebral bodies, the presence of large epiphyseal ossification centers and wide growth plates in the long tubular bones, and numerous pseudoepiphyses of the short tubular bones in hands and feet.
Rare bone diseases 
