Opsismodysplasia (OPSMD) is a rare skeletal dysplasia involving delayed bone maturation. Clinical signs observed at birth include short limbs, small hands and feet, relative macrocephaly with a large anterior fontanel, and characteristic craniofacial abnormalities including a prominent brow, depressed nasal bridge, a small anteverted nose, and a relatively long philtrum. Death in utero or secondary to respiratory failure during the first few years of life has been reported, but there can be long-term survival. Typical radiographic findings include shortened long bones with delayed epiphyseal ossification, severe platyspondyly, metaphyseal cupping, and characteristic abnormalities of the metacarpals and phalanges (summary by Below et al., 2013 and Fradet and Fitzgerald, 2017).

The Strudwick type of spondyloepimetaphyseal dysplasia (SEMD) is characterized by disproportionate short stature, pectus carinatum, and scoliosis, as well as dappled metaphyses (summary by Tiller et al., 1995).

The Torrance type of platyspondylic lethal skeletal dysplasia (PLSDT) is an autosomal dominant disorder characterized by varying platyspondyly, short ribs with anterior cupping, hypoplasia of the lower ilia with broad ischial and pubic bones, and shortening of the tubular bones with splayed and cupped metaphyses. Histology of the growth plate typically shows focal hypercellularity with slightly enlarged chondrocytes in the resting cartilage and relatively well-preserved columnar formation and ossification at the chondroosseous junction. Though generally lethal in the perinatal period, longer survival has been reported (summary by Zankl et al., 2005).

The Borochowitz-Cormier-Daire type of spondyloepimetaphyseal dysplasia (SEMDBCD) is a rare type of autosomal recessive short-limb short-trunk dwarfism. Affected individuals have significant short stature with pronounced leg bowing, lumbar lordosis, and a waddling gait (summary by Borochowitz et al., 2004 and Shyamasundar et al., 2020).

Syndrome with characteristics of pelviscapular dysplasia with epiphyseal abnormalities, congenital dwarfism and facial dysmorphism. The facial dysmorphism has manifestations of frontal bossing, hypertelorism, narrow palpebral fissures, deep-set eyes, strabismus, low-set posteriorly rotated and malformed ears, dysplasia of conchae, a small chin, a short neck with redundant skin folds, and a low hairline. Intelligence may vary from normal to moderately impaired. Radiographic features comprise aplasia of the body of the scapula, hypoplasia of the iliac bone, humeroradial synostosis, dislocation of the femoral heads, and moderate brachydactyly. Mutations in the TBX15 gene have been identified as potentially causative. Pelviscapular dysplasia is phenotypically similar to pelvis-shoulder dysplasia.

Severely hypoplastic and triangular-shaped tibiae and absence of the fibulae.Two sporadic cases have been described. Moderate mesomelia of the upper limbs, proximal widening of the ulnas, pelvic anomalies and marked bilateral glenoid hypoplasia also reported.

Fibrochondrogenesis is a severe skeletal dysplasia characterized by a flat midface, short long bones, short ribs with broad metaphyses, and vertebral bodies that show distinctive hypoplastic posterior ends and rounded anterior ends, giving the vertebral bodies a pinched appearance on lateral radiographic views. The chest is small, causing perinatal respiratory problems which usually, but not always, result in lethality. Affected individuals who survive the neonatal period have high myopia, mild to moderate hearing loss, and severe skeletal dysplasia (summary by Tompson et al., 2012). For a discussion of genetic heterogeneity of fibrochondrogenesis, see FBCG1 (228520).

Bent bone dysplasia syndrome-1 (BBDS1) is a perinatal lethal skeletal dysplasia characterized by poor mineralization of the calvarium, craniosynostosis, dysmorphic facial features, prenatal teeth, hypoplastic pubis and clavicles, osteopenia, and bent long bones (Merrill et al., 2012). Genetic Heterogeneity of Bent Bone Dysplasia Syndrome BBDS2 (620076) is caused by mutation in the LAMA5 gene (601033) on chromosome 20q13.

Short-rib thoracic dysplasia (SRTD) with or without polydactyly refers to a group of autosomal recessive skeletal ciliopathies that are characterized by a constricted thoracic cage, short ribs, shortened tubular bones, and a 'trident' appearance of the acetabular roof. SRTD encompasses Ellis-van Creveld syndrome (EVC) and the disorders previously designated as Jeune syndrome or asphyxiating thoracic dystrophy (ATD), short rib-polydactyly syndrome (SRPS), and Mainzer-Saldino syndrome (MZSDS). Polydactyly is variably present, and there is phenotypic overlap in the various forms of SRTDs, which differ by visceral malformation and metaphyseal appearance. Nonskeletal involvement can include cleft lip/palate as well as anomalies of major organs such as the brain, eye, heart, kidneys, liver, pancreas, intestines, and genitalia. Some forms of SRTD are lethal in the neonatal period due to respiratory insufficiency secondary to a severely restricted thoracic cage, whereas others are compatible with life (summary by Huber and Cormier-Daire, 2012 and Schmidts et al., 2013). There is phenotypic overlap with the cranioectodermal dysplasias (Sensenbrenner syndrome; see CED1, 218330).