2000-07-24-01 Campomelic dysplasia © Silva www.thefetus.net/
Updated 2006-01-18 by Juliana Leite, MD
Original text 2000-07-24 Philippe Jeanty, MD, PhD & Sandra R Silva, MD
Definition: Campomelic dysplasia is a congenital disorder characterized by development of abnormal curvature of the long bones, particularly from lower extremities, such as femur and tibiae. Some authors have classified the disease into two varieties: “long limbed” and “short limbed,” depending on the type of limbs involved in the pathological process.
Synonyms: Camptomelic dysplasia, campomelic syndrome, campomelic dwarfism, congenital bowing of the limbs.
Prevalence: The disorder affects 0.02:10,000 live births. Sex reversal occurs in some genotypic males with lack the H-Y antigen. Phenotypic sex ratio is approximately M1:F2.3, karyotypic sex ratio is approximately M2:F13.
Etiology: The transmission of campomelic dysplasia is still discussed. Autosomal recessive inheritance is thought to be the most common pattern, although it may happens also due to sporadic autosomal dominant mutation.
Recurrence risk: Depends on the etiology. If transmitted by autosomal recessive pattern it has a 25% recurrence risk. When transmitted by autosomal dominant pattern, it has 50% recurrence risk, but in fact most are new mutations.
Diagnosis: The most characteristic sign of campomelic dysplasia is the marked anterior bowing of the long bones, particularly of femur (figs. 1-2) and tibia. Severe angulation may mimic fractures. Other sonographic features that are commonly present include, growth restriction, bell-shaped narrow chest, eleven pair of ribs, hypoplasia of the mid-thoracic vertebral bodies, fibula, and scapula, scoliosis, shortness of the limbs, talipes equinovarus, tracheobronchomalacia, flat and small face, high forehead with prominent occiput, low nasal bridge, micrognathia, cleft of the soft palate, hypertelorism, low-set and malformed ears, hydrocephalus, and ambiguous genitalia.
Figure 1: Bowing of the ulna. Note the gentle curve that sometimes differentiate these from the more acute angles of the osteogenesis imperfecta fetuses.
Figure 2: Bowing of the femur.
Genetic anomaly: A mutation in SOX9, a sex-determining region of Y (SRY) related gene, located at 17q24 seems to be associated with the occurrence of both campomelic dysplasia and sex reversal.
Pathogenesis: Although many theories have been proposed to explain the development of the anomalies present in this syndrome, (in particular the bowing of the bones), the precise mechanism is not known. Some of the theories are:
1) mechanical stress due to faulty fetal position within the uterus.
2) primary muscle imbalance and shortening, particularly of the calf muscles causing secondary bending of the tibia.
3) intrauterine fracture with subsequent healing.
4) abnormal vascular and cellular elements of perichondrium.
5) developmental disturbance in the cartilagineous phase of bone formation.
Associated anomalies: Polyhydramnios, and anomalies from the central nervous, cardiac, and renal systems have been described prenataly6. After birth, hearing loss may occur.
Differential diagnosis: Osteogenesis imperfecta type I and II, hypophosphatasia, unclassifiable varieties of congenital bowing of the long bones, thanatophoric dysplasia, mesomelic dysplasia (Reinhart variety), Roberts syndrome and diastrophic dysplasia5.
Prognosis: Almost all result in neonatal or infant death, due to respiratory complications. Some survivors, including a boy alive at 17 years, have been reported.
Management: Before viability, the option of pregnancy termination should be offered. After viability, standard obstetrical management is not altered, and respiratory function in the newborn must be supported.
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