Autosomal recessive inheritance in camptomelic dwarfism

Campomelic Skeleta-l Dysplasia with a Narrow Thorax

This report describes the typical findings of campmelic skeletal dysplasia, a rare congenital disorder characterized by bent femurs, a narrow chest, and usually, a fatal outcome.

Testis determination in mammals: more questions than answers

In humans, testis development depends on a regulated genetic hierarchy initiated by the Y-linked SRY gene. Failure of testicular determination results in the condition termed 46,XY gonadal dysgenesis (GD). Several components of the testis determining pathway have recently been identified though it has been difficult to articulate a cascade with the known elements of the system. It seems, however, that early gonadal development is the result of a network of interactions instead of the outcome of a linear cascade. Accumulating evidence shows that testis formation in man is sensitive to gene dosage. Haploinsufficiency of SF1, WT1 and SOX9 is responsible for 46,XY gonadal dysgenesis. Besides, data on SRY is consistent with possible dosage anomalies in certain cases of male to female sex reversal. 46,XY GD due to monosomy of distal 9p and 10q might also be associated with an insufficient gene dosage effect. Duplications of the locus DSS can lead to a failure of testicular development and a duplication of the region containing SOX9 has been implicated in XX sex reversal. Transgenic studies in mouse have shown, however, that this mammal is less sensitive to gene dosage than man. Here, we will try to put in place the known pieces of the jigsaw puzzle that is sex determination in mammals, as far as current knowledge obtained from man and animal models allows. We are certain that from this attempt more questions than answers will arise.

The treatment of progressive kyphoscoliosis in camptomelic dysplasia

STUDY DESIGN

This study evaluated the different forms of treatment of camptomelic dysplasia, a rare form of short-limbed dwarfism.

OBJECTIVES

To determine the most efficacious form of management of spinal deformities in camptomelic dysplasia.

SUMMARY OF BACKGROUND DATA

The literature on treatment of spinal deformities in camptomelic dysplasia is sparse. One report advocates aggressive surgical treatment to prevent curve progression and prevent already compromised respiratory function.

METHODS

Eight patients with camptomelic dysplasia and progressive spinal deformity underwent a retrospective chart and radiographic review by an independent observer. Follow-up averaged 3 years and 9 months.

RESULTS

Five of eight patients initially were treated with bracing and six of eight patients eventually required surgery. Average initial kyphosis was 114 degrees and scoliosis 61 degrees, compared with 99 degrees kyphosis and 52 degrees scoliosis at follow-up. Complications included pseudarthrosis (50%) and neurologic problems (33%).

CONCLUSIONS

The authors advocate anterior/posterior uninstrumented fusion and halo cast immobilization postoperatively to prevent curve progression and avoid the potentially fatal sequelae associated with this disorder.

Mutations in SOX9 cause both autosomal sex reversal and campomelic dysplasia

The human testis determining factor (SRY) has been cloned from the Y chromosome. This gene is a dominant inducer of male differentiation. Mutations in the SRY gene result in an XY individual developing as a sex reversed phenotypic female. Sex reversal in humans can also be caused by mutations located in autosomal or X-linked loci. One such sex-reversing locus (SRAI) is associated with the developmental disorder campomelic dysplasia (CD). Both these syndromes were mapped to human chromosome 17q by the identification of balanced reciprocal translocations in five unrelated patients. The translocation breakpoint of one such XY-female CD patient was mapped and the region surrounding it cloned. The closest distal marker used to map the translocation breakpoint was the SOX9 gene. Because of the close proximity of this gene to the breakpoint, it was subjected to mutation analysis in patients without overt chromosome rearrangements. Analysis of DNA from these patients and their parents identified de novo mutations in the SOX9 gene in patients with both autosomal sex reversal and CD. This showed that mutations in the SOX9 gene are responsible for both syndromes.

Campomelic dysplasia and autosomal sex reversal caused by mutations in an SRY-related gene

Induction of testis development in mammals requires the presence of the Y-chromosome gene SRY. This gene must exert its effect by interacting with other genes in the sex-determination pathway. Cloning of a translocation chromosome breakpoint from a sex-reversed patient with campomelic dysplasia, followed by mutation analysis of an adjacent gene, indicates that SOX9, an SRY-related gene, is involved in both bone formation and control of testis development.

Campomelic dysplasia: evidence of autosomal dominant inheritance

We present a mother and daughter with clinical and radiological findings consistent with the diagnosis of campomelic dysplasia. Milder tibial bowing and significant shortening of the phalangeal bones of both hands and feet may distinguish this from the classical autosomal recessive form of the disease.

A chromosome 17q de novo paracentric inversion in a patient with campomelic dysplasia; case report and etiologic hypothesis

The campomelic syndrome is a skeletal dysplasia with a characteristic pattern of deformity involving the proximal and distal extremities, pelvic and shoulder girdles, thoracic cage and palate. Respiratory compromise often leads to death in early infancy. Etiology has not been determined although evidence suggests genetic heterogeneity in patients with campomelia. Cytogenetic analysis in the past have revealed an unexpectedly high incidence of a 46, XY karyotype in phenotypic females. We report here on a patient with a typical case of campomelic dysplasia in whom a de novo paracentric inversion of chromosome 17q was identified. Review of the genetic map of the inverted region identified potential "structural" genes including the Hox-2-homeobox gene and the collagen gene, COLIA1, which may be involved in the pathogenesis of campomelic syndrome.

Bronchoscopic evaluation of airway obstruction in campomelic dysplasia

Campomelic dysplasia is a generalized disorder of cartilaginous growth and development, leading to early death from pulmonary insufficiency. We describe the airway dynamics as observed bronchoscopically in two affected infants. Both infants demonstrated anatomic compromise of the upper airway and diffuse laryngotracheobronchomalacia. Additionally, both had a characteristically small, bell-shaped thoracic cage. The abnormal airway dynamics produced serious inspiratory and expiratory obstruction in these infants and, in combination with the restrictive chest wall defect, led rapidly to the development of respiratory failure. While palliative procedures such as tracheostomy may temporarily improve airway dynamics, future respiratory tract insults may prove fatal.

Campomelic syndrome: concepts of the bowing and shortening in the lower limbs

A comprehensive study (bone roentgenography, arteriography, gross dissection, microscopy of the long bones, and biochemical study of proteoglycan-aggregates in the hyaline cartilage) of the lower limbs in a full-term stillborn with the campomelic syndrome was performed. Hyaline cartilage immaturity of the long bones, dysplasia of growth plates, focal shaft dysplasia, and a defective length of the posterior femur and crus muscles were revealed. The genesis of the bowing and shortening of the long bones in the lower limbs is discussed.

Radiology and histopathology of the bent limbs in campomelic dysplasia: implications in the aetiology of the disease and review of theories

The study of the bent bones in a case of campomelic dysplasia and a review of the literature suggest a repair process at the site of angulation. A theory that can explain most of the features of the disease is presented; it supposes a damage of the cartilage model at the midshaft, followed by a fracture of the thin bone collar in the earlier stage of ossification of the diaphysis.

The campomelic syndrome: review, report of 17 cases, and follow-up on the currently 17-year-old boy first reported by Maroteaux et al in 1971

We report 17 cases of the campomelic syndrome (CS) and a follow-up of one of the original patients of Maroteaux et al who is now 17 years old. Our review is based on 97 patients, including our own. An infant with the CS presents at birth with spectacularly short and bowed femora and tibiae. The initial chest radiograph confirms the diagnosis by demonstrating extremely small bladeless scapulae and hypoplastic pedicles of many thoracic vertebrae. Ossification of the sternal segments, pubis, talus, and knee epiphyses is also retarded. Usually the hips are dislocated and talipes equinovarus deformities are present. There is a small chondrocranium and a disproportionately large neurocranium. The bell-shaped chest, narrow superiorly, does not explain the degree of respiratory distress that soon ensues. Narrow airways from defective tracheo-bronchial cartilage can often be demonstrated on the radiograph, but micrognathia, retroglossia, cleft palate, hypoplastic lungs, and even CNS-based hypotonia contribute to the respiratory problem. Internal anomalies include frequent absence of olfactory bulbs and tracts and dilatation of cerebral ventricles, heart defects (PDA, VSD, stenosis of aortic isthmus), hydroureter and hydronephrosis, renal hypoplasia, renal hypoplasia, and rarely renal cysts.

The campomelic syndrome in a singleton and monozygotic twins

We describe here three patients with the campomelic syndrome, two of whom were identical twins. Both twins were phenotypically female but had an XY chromosome complement.

The camptomelic syndrome in two female siblings

A patient is reported whose only two pregnancies resulted in phenotypically and genotypically female infants with camptomelic syndrome of the long-limbed variety. Both infants died within a few minutes of birth.