Chondrodysplasia punctata

Description

This is a heterogeneous group of bone dysplasias characterized by stippling of the epiphyses in infancy. Several types have been described and the incidence is 1 in 100,000 live births. The most common varieties will be described in this text. CP brachytelephalangic type: This X-linked recessive disorder has characteristic facial dysmorphism, normal trunk and limbs, mild growth disturbance and short hands and feet. The newborn may show punctate calcifications (stippling) in the tarsal bones, vertebral bodies and sacrum. Vertebral body sagittal clefts may be present. There is brachydactyly with proximal metacarpal and phalangeal hypoplasia and stippling. The stippling disappears with age. CP Conradi-Hunermann type: is one of the most common types although it is reported in only 14 families. Inheritance is autosomal dominant consisting mostly of new mutations . Similarly it also features craniofacial dysmorphism with frontal bossing, a flat nasal bridge, hypertelorism, cataracts and a high-arched palate. There are cutaneous abnormalities and mild asymmetric limb shortening. Skeletal manifestations may be minimal or absent. Punctate calcific deposits can be seen in areas of cartilage and soft tissue surrounding joints. This condition may present with a wide range of findings with most cases surviving into adulthood although a lethal subgroup has been described. CP rhizomelic type: This is also a very frequent type transmitted in an autosomal recessive fashion. It may represent a peroxisomal protein import disorder. It features rhizomelic limb shortening, facial dysmorphism, cataracts, icthyosiform skin lesions, alopecia and joint contractures. There is symmetric shortening of proximal and other long bones, stippling of the cartilaginous skeleton and periarticular regions, mild or absent stippling of the axial skeleton and vertebral body coronal clefts. It is usually fatal within the first year of life. CP Sheffield type: This is a mild sporadic form that presents with an abnormal, typical facies with a flattened tip of the nose, depressed nasal bridge, failure to thrive, mild mental retardation, 2:1 male-female ratio and older parental age. There is stippling of the calcaneus in infancy, occasionally in the sacrum and rarely in other areas. Laryngeal calcification and sagittal and coronal vertebral body clefts can also be present. CP tibial-metacarpal type: This type is sporadic and presents with short stature, a hypoplastic midface with depressed nasal bridge, micrognathia and normal psychomotor development. There is variable shortening of the femur and humerus with a short tibia, a long fibula and distal ulna hypoplasia. The hands feature brachydactyly with short fourth metacarpal and variable distal phalangeal shortening. There is stippling of the sacrum, tarsal, carpal and metacarpal bones. Vertebral body coronal clefts can be seen. CP X-linked dominant (Happle) type: This is a lethal condition in males and may have mild affectation in females. It presents with short stature, asymmetric limb shortening, cataracts, scoliosis, circumscribed alopecia, linear or blotchy skin lesions and flexion contractures. The long bone shortening affects principally the femur and humerus, is asymmetric, and is very similar to the Conradi-Hunermann type. There is stippling of the epiphyses and vertebral column, but it gradually disappears later in life. Vertebral body clefts and wedging can also be seen. CP X-linked recessive (Curry) Type: The aetiology of this type seems to be related to a gene abnormality in the short arm of chromosome X. There is a variable complex phenotype with mild short stature, mental retardation, ichthyosis, nasal hypoplasia, cataracts and sparse hair. The radiologic findings are similar to the Conradi Hunermann type, with diffuse stippling of epiphyseal, paravertebral, laryngeal and tracheal areas. The long bones are of normal length, have abnormal metaphyseal cupping and there is distal phalangeal hypoplasia. Female carriers often have mild short stature. The absence of steroid sulfatase enzyme activity in amniocytes has been reported.