Ellis–Van Creveld Syndrome

The Ellis-van Creveld syndrome (OMIM 225500), also known as chondroectodermal dysplasia, is a skeletal and an ectodermal dysplasia. The skeletal dysplasia presents at birth with short limbs, especially the middle and distal segments, accompanied by postaxial polydactyly of the hands and sometimes of the feet. Nail dysplasia and dental anomalies (including neonatal, absent, and premature loss of teeth and upper lip defects) constitute the ectodermal dysplasia. Common manifestations also include atrial septal defects and other congenital heart defects.

Skeletal radiographs reveal short tubular bones with clubbed ends, especially the proximal tibia and ulna (Fig. 691-1). Carpal bones display extra ossification centers and fusion; cone-shaped epiphyses are evident in the hands. A bony spur is often noted above the medial aspect of the acetabulum.

Figure 691-1 Radiograph of lower extremities in Ellis-van Creveld syndrome. Tubular bones are short, and proximal fibula is short. Ossification is retarded in lateral tibia epiphyses, causing a knock-knee deformity.

Ellis-van Creveld syndrome is an autosomal recessive trait that occurs most often in the Amish. Mutations have been identified in one of two genes, EVC (EVC1) and EVC2, which map in a head-to-head configuration to chromosome 4p. The functions of the gene products are unknown. About 30% of patients die of cardiac or respiratory problems during infancy. Life span is otherwise normal; adult heights range from 119 to 161 cm.

Asphyxiating Thoracic Dystrophy

Asphyxiating thoracic dystrophy (OMIM 208500), or Jeune syndrome, is an autosomal recessive chondrodysplasia that resembles Ellis-van Creveld syndrome. Newborn infants present with a long, narrow thorax and respiratory insufficiency associated with pulmonary hypoplasia. Neonates often die. Other neonatal manifestations include slightly short limbs and postaxial polydactyly. Mutations have been identified in the gene encoding cytoplasmic dynein 2 heavy chain 1 (DYNC2H1), which maps to chromosome 11q14.3-q23.1.

Skeletal radiographs show very short ribs with anterior expansion. Tubular limb bones are short with bulbous ends; cone-shaped epiphyses occur in hand bones. The iliac bones are short and square with a spur above the medial aspect of the acetabulum.

If infants survive the neonatal period, respiratory function usually improves as the rib cage grows. Surgery that produces lateral thoracic expansion improves rib growth and enhances chest wall dimensions. Progressive renal dysfunction often develops during childhood. Intestinal malabsorption and hepatic dysfunction have also been reported.

Short-Rib Polydactyly Syndromes

Four types of short-rib polydactyly syndrome (types I-IV) (OMIM 263530, 263520, 263510, 269860) have been described. All are lethal in the newborn period. Neonates present with respiratory distress, an extremely small thorax, very short extremities, polydactyly, and a variety of nonskeletal defects. Radiographs demonstrate very short ribs and tubular bones with changes characteristic for each type. All four types are autosomal recessive traits. Mutations of DYNC2H1 have been detected in short-rib polydactyly syndrome type III, making it allelic to asphyxiating thoracic dystrophy.

Cartilage-Hair Hypoplasia

Cartilage-hair hypoplasia (CHH) (OMIM 250250) is also known as metaphyseal chondrodysplasia—McKusick type. It is recognized during the 2nd year because of growth deficiency affecting the limbs, accompanied by flaring of the lower rib cage, a prominent sternum, and bowing of the legs. The hands and feet are short, and the fingers are very short with extreme ligamentous laxity. The hair is thin, sparse, and light colored, and nails are hypoplastic. The skin is hypopigmented.

Radiographs show short tubular bones with flared, irregularly mineralized, and cupped metaphyses (Fig. 691-2). The knees are more affected than are the hips, and the fibula is disproportionately longer than the tibia. The metacarpals and phalanges are short and broad. Spinal radiographs reveal mild platyspondyly.

Figure 691-2 Radiograph of lower extremities in cartilage-hair hypoplasia. The tubular bones are short and the metaphyses are flared and irregular. The fibula is disproportionately long compared with the tibia. The femoral necks are short.

Nonskeletal manifestations associated with CHH include immunodeficiency (T-cell abnormalities, neutropenia, leukopenia, and susceptibility to chickenpox; children also may have complications from smallpox and polio vaccinations), malabsorption, celiac disease, and Hirschsprung disease. Adults are at risk for malignancy, especially non-Hodgkin lymphoma and skin tumors. Adults reach heights of 107-157 cm.

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