OBSOLETE: Platyspondylic lethal chondrodysplasia

Platyspondylic lethal chondrodysplasia (also known as platyspondylic lethal skeletal dysplasia) was a historical umbrella term used to describe a group of severe, lethal skeletal disorders characterized by extreme platyspondyly (markedly flattened vertebral bodies), short-limbed dwarfism, and a small thorax. This designation is now considered obsolete (Orphanet code 1417) because advances in molecular genetics have allowed the conditions previously grouped under this name to be reclassified into distinct entities. These include platyspondylic lethal skeletal dysplasia, Torrance type (caused by mutations in COL2A1), San Diego type (also linked to COL2A1), and Luton type, among others. Some cases originally classified under this umbrella have been reclassified as thanatophoric dysplasia or other type II collagenopathies. Clinically, affected infants presented with profound shortening of the limbs (micromelia), a narrow thorax leading to respiratory insufficiency, a large head with frontal bossing, and severely flattened vertebral bodies visible on radiographs. The skeletal system was the primary organ system affected, with abnormal endochondral ossification leading to disorganized growth plate cartilage. The condition was uniformly lethal in the perinatal period, with death typically resulting from respiratory failure due to pulmonary hypoplasia secondary to the small thoracic cage. Because this classification is obsolete, patients and families seeking information should refer to the specific subtypes now recognized as separate disorders. No specific treatments existed for these conditions beyond supportive care. Genetic counseling is recommended for families, as the inheritance pattern varies depending on the specific molecular diagnosis — some forms follow autosomal dominant inheritance (often arising as de novo mutations), while others may be autosomal recessive.

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