Introduction Achondrogenesis II, hypochondrogenesis, platyspondylic Torrance type, spondyloepiphyseal dysplasia congenita (SEDC) ( Chapter 56 ), Kniest dysplasia, spondyloepimetaphyseal dysplasia, Strudwick type, Legg-Calve-Perthes disease, spondyloperipheral dysplasia, spondyloepiphyseal dysplasia with metatarsal shortening (Czech type), autosomal dominant spondyloarthropathy, and Stickler syndrome form the type II collagen disorder group. This group is a continuous spectrum of disorders, some of which manifest in the prenatal period, some much later in life.…

Introduction Spondyloepiphyseal dysplasias are rare, nonlethal disorders of bone growth. These disorders primarily affect the spine (spondylo-) and the ends of the long bones (epiphyseal), resulting in a short-trunk dwarfism. These disorders are clinically and genetically heterogeneous. Some spondyloepiphyseal dysplasias manifest in the prenatal period, including spondyloepiphyseal dysplasia congenita (SEDC), whereas others manifest in childhood. Other spondyloepiphyseal dysplasias are diagnosed in later life as early-onset arthropathy.…

Introduction The short-rib polydactyly syndromes (SRPSs) are a genetically heterogeneous group of autosomal recessive skeletal disorders. Characteristic findings in SRPS include short horizontal ribs, shortened appendicular long bones limbs, and polydactyly. Historically, four distinct SRPS types have been recognized : SRPS I (Saldino-Noonan syndrome) SRPS II (Majweski syndrome) SRPS III (Verma-Naumoff syndrome) SRPS IV (Beemer-Langer syndrome) Currently the SRPSs are classified as “ Ciliopathies with major…

Introduction Russell-Silver syndrome (RSS) or Silver-Russell syndrome is one of the growth deficiency disorders that form part of the increasing group of congenital imprinting disorders. RSS is characterized by severe intrauterine and postnatal growth restriction. Other abnormalities include relative macrocephaly, hemihypertrophy (one side of the body is larger than the other), fifth finger clinodactyly, and triangular-shaped facies. RSS is genetically heterogeneous and the phenotype can vary.…

Introduction Ultrasound (US) evaluation of a fetus with a radial ray defect is a difficult diagnostic dilemma because the defect may be isolated, but can also result from chromosomal aneuploidy, teratogenic exposure, and more than 200 distinct genetic syndromes, including skeletal dysplasias, particularly those associated with mesomelia. Radial aplasia or hypoplasia is a rare abnormality occurring in 2 : 10,000 liveborns, but more common than isolated ulnar abnormalities.…

Introduction Osteogenesis imperfecta (OI), a disorder of bone characterized by hypomineralization of the skeleton, was the first disorder proposed to be due to a defect in collagen. It is characterized by life-long bone fragility and fracture predisposition. Other features, depending on the type of OI, may include blue sclerae, hearing loss, hypermobility of joints, and abnormal dentition. OI is marked by considerable clinical and genetic heterogeneity.…

Introduction Hypophosphatasia (HPP) is an autosomal recessive disorder that is characterized by poor mineralization of bones and teeth. There are at least six phenotypes, which are distinguished from each other by age at diagnosis, inheritance pattern, and prognosis. The primary forms are named for age at diagnosis and include perinatal (lethal), infantile, childhood, and adult HPP. In most cases that are diagnosed perinatally, infants are either…

Introduction Fibroblast growth factor receptor 3 (FGFR3) disorders compromise of a spectrum of disorders that include thanatophoric dysplasia, achondroplasia, and hypochondroplasia, among other rare disorders such as severe achondroplasia with developmental delay and acanthosis nigricans (SADDAN), and craniosyntoses syndromes. They are all inherited as autosomal dominant disorders due to heterozygosity for mutations in FGFR3 . Achondroplasia is the most frequent cause of nonlethal dwarfism and is…

Introduction Diastrophic dysplasia (DTD) is an autosomal, recessively inherited skeletal dysplasia characterized by short limbs, normal-sized skull, cleft palate in one-third of patients, characteristic swelling of the pinnae cartilage, contractures of the large joints with deformities, spinal abnormalities (scoliosis, exaggerated lumbar lordosis, cervical kyphosis), and a distinct brachydactyly associated with the characteristic “hitchhiker” thumbs. Newborns with DTD have an increased risk of mortality in the neonatal…

Introduction Chondrodysplasia punctata refers to a group of skeletal dysplasias that are characterized primarily by punctate calcifications in cartilage (calcific stippling). These disorders are characterized by short-limb dwarfism, spinal abnormalities, facial dysmorphisms, joint contractures, skin lesions, and occasionally cardiac malformations. There are multiple types of chondrodysplasia punctata, and there is extensive locus and allelic heterogeneity. Disorder Definition The term chondrodysplasia punctata describes a group of osteochondrodysplasias…

Introduction Campomelic dysplasia (CD) is a skeletal dysplasia characterized by abnormal facies, multiple congenital anomalies, a typical pattern of skeletal abnormalities, and frequent male-to-female sex reversal. Newborns with CD often die as a result of respiratory insufficiency and congenital anomalies. A small subset of individuals with clinical features of CD lack characteristic long bone bowing and are classified as having acampomelic campomelic dysplasia. CD results from…

Introduction Atelosteogenesis (AO) refers to a group of lethal short-limb skeletal dysplasias characterized by an abnormal, characteristic facies and hypoplastic or dysplastic tubular bones. Specific radiographic abnormalities, distinct histopathology, and differing inheritance patterns distinguish the three well-recognized types of AO. All three forms have abnormal facies and short limbs, but associated findings help distinguish them from each other; for example, synpolydactyly, omphalocele, and frontal encephalocele are…