A missense T (Brachyury) mutation contributes to vertebral malformations.

No major susceptibility genes for sporadically occurring congenital vertebral malformations (CVM) in humans have been identified to date. Body patterning genes whose mutants cause axial skeletal anomalies in mice are candidates for human CVM susceptibility. T (also known as Brachyury) and TBX6 are critical genes needed to establish mesodermal identity. We hypothesized that mutations in T and/or TBX6 contribute to the pathogenesis of human CVMs. The complete T and TBX6 coding regions, splice junctions, and proximal 500 bp of the promoters were sequenced in 50 phenotyped patients with CVM. Three unrelated patients with sacral agenesis, Klippel-Feil syndrome, and multiple cervical and thoracic vertebral malformations were heterozygous for a c.1013C>T substitution, resulting in a predicted Ala338Val missense alteration in exon 8. A clinically unaffected parent of each patient also harbored the substitution, but the variant did not occur in an ethnically diverse, 443-person reference population. The c.1013C>T variant is significantly associated with CVM (p < 0.001). Alanine 338 shows moderate conservation across species, and valine at this position has not been reported in any species. A fourth patient harbored a c.908-8C>T variant in intron 7. This previously unreported variant was tested in 347 normal control subjects, and 11 heterozygotes and 2 T/T individuals were found. No TBX6 variants were identified. We infer that the c.1013C>T substitution is pathogenic and represents the first report of an association between a missense mutation in the T gene and the occurrence of sporadic CVMs in humans. It is uncertain whether the splice junction variant increases CVM risk. TBX6 mutations do not seem to be associated with CVM. We hypothesize that epistatic interactions between T and other developmental genes and the environment modulate the phenotypic consequences of T variants.

Management of distal tibial medial malleolus type-6 physeal fractures.

PURPOSE: Type 6 is an open fracture in which part of the physis is missing. It is the least common physeal fracture, but has the highest rate of complications, particularly the formation of a physeal bar. Without preemptive treatment, a physeal bar always forms, producing growth retardation and angular deformity, and excision of these physeal bars has been uniformly unsuccessful. The distal medial malleolus is a common site for the fracture. METHODS: Strategies for the treatment of two varieties of acute medial malleolar type-6 fractures and two types of late deformities following type-6 fracture are given. The acute fractures were treated with either fat or cartilage applied to the exposed physis. The late deformities were treated with corrective iliac bone grafting. RESULTS: The acute fractures were prevented from forming physeal bars and the two late deformities were fully corrected with good outcomes. CONCLUSION: Fat applied to an acute type-6 physeal fracture has a good chance of preventing bar formation. Ankle deformities due to bars can be corrected by means of iliac bone grafting.

Lack of evidence of WNT3A as a candidate gene for congenital vertebral malformations.

BACKGROUND: Prior investigations have not identified a major locus for vertebral malformations, providing evidence that there is genetic heterogeneity for this condition. WNT3A has recently been identified as a negative regulator of Notch signaling and somitogenesis. Mice with mutations in Wnt3a develop caudal vertebral malformations. Because congenital vertebral malformations represent a sporadic occurrence, linkage approaches to identify genes associated with human vertebral development are not feasible. We hypothesized that WNT3A mutations might account for a subset of congenital vertebral malformations. METHODS: A pilot study was performed using a cohort of patients with congenital vertebral malformations spanning the entire vertebral column was characterized. DNA sequence analysis of the WNT3A gene in these 50 patients with congenital vertebral malformations was performed. RESULTS: A female patient of African ancestry with congenital scoliosis and a T12-L1 hemivertebrae was found to be heterozygous for a missense variant resulting in the substitution of alanine by threonine at codon 134 in highly conserved exon 3 of the WNT3A gene. This variant was found at a very low prevalence (0.35%) in a control population of 443 anonymized subjects and 1.1% in an African population. CONCLUSION: These data suggest that WNT3A does not contribute towards the development of congenital vertebral malformations. Factors such as phenotypic and genetic heterogeneity may underlie our inability to detect mutations in WNT3A in our patient sample.

DLL3 as a candidate gene for vertebral malformations.

Investigations have not identified a major locus for congenital vertebral malformations. Based on observations in mice, we hypothesized that mutations in DLL3, a member of the notch-signaling pathway, might contribute to human vertebral malformations. We sequenced the DLL3 gene in 50 patients with congenital vertebral malformations. A Caucasian male patient with VACTERL manifestations including a T5-T6 block vertebrae was heterozygous for a "G" to "A" missense mutation changing glycine to arginine at codon 269. This residue is conserved in mammals, including chimpanzee, mouse, dog, and rat. Additional testing in the patient did not show evidence of chromosome abnormalities. The patient's asymptomatic mother was also heterozygous for the missense mutation. Since this mutation was not observed in a control population and leads to an amino acid change, it may be clinically significant. The mutation was not found in a control population of 87 anonymous individuals. Several established mechanisms could explain the mutation in both the patient and his asymptomatic mother (susceptibility allele requiring additional environmental factors, somatic mosaicism, multigenic inheritance). Documenting the absence of the mutation in a larger control population or the presence of the mutation in additional affected patients, or documenting a functional difference in DLL3 would provide further evidence supporting its causal role.

Alveolar soft-part sarcoma responsive to intensive chemotherapy.

Alveolar soft-part sarcoma (ASPS) is a very rare malignant tumor, usually of the extremities, and is seen most often in adolescents and young adults. Surgical excision of the primary and pulmonary metastases has resulted in prolonged survival in some patients, but adjuvant radiation and/or chemotherapy are generally thought to be ineffective. The authors describe a 13-year-old patient with ASPS of an extremity who presented with multiple bilateral pulmonary metastases at diagnosis. Following intensive multiagent chemotherapy, pulmonary metastases showed in vivo evidence of tumor death. The patient has remained disease-free for 10 years following treatment.

Congenital and idiopathic scoliosis: clinical and genetic aspects.

OBJECTIVE: Genetic and environmental factors influencing spinal development in lower vertebrates are likely to play a role in the abnormalities associated with human congenital scoliosis (CS) and idiopathic scoliosis (IS). An overview of the molecular embryology of spinal development and the clinical and genetic aspects of CS and IS are presented. Utilizing synteny analysis of the mouse and human genetic databases, likely candidate genes for human CS and IS were identified. DESIGN: Review and synteny analysis. METHODS: A search of the Mouse Genome Database was performed for "genes," "markers" and "phenotypes" in the categories Neurological and neuromuscular, Skeleton, and Tail and other appendages. The Online Mendelian Inheritance in Man was used to determine whether each mouse locus had a known human homologue. If so, the human homologue was assigned candidate gene status. Linkage maps of the chromosomes carrying loci with possibly relevant phenotypes, but without known human homologues, were examined and regions of documented synteny between the mouse and human genomes were identified. RESULTS: Searching the Mouse Genome Database by phenotypic category yielded 100 mutants of which 66 had been mapped. The descriptions of each of these 66 loci were retrieved to determine which among these included phenotypes of scoliosis, kinky or bent tails, other vertebral abnormalities, or disturbances of axial skeletal development. Forty-five loci of interest remained, and for 27 of these the comparative linkage maps of mouse and human were used to identify human syntenic regions to which plausible candidate genes had been mapped. CONCLUSION: Synteny analysis of mouse candidate genes for CS and IS holds promise due to the close evolutionary relationship between mice and human beings. With the identification of additional genes in animal model systems that contribute to different stages of spine development, the list of candidate genes for CS and IS will continue to grow.

A comparison of the effects of solid, articulated, and posterior leaf-spring ankle-foot orthoses and shoes alone on gait and energy expenditure in children with spastic diplegic cerebral palsy.

Fourteen children with spastic diplegic cerebral palsy were evaluated wearing threedifferent ankle-foot orthoses and shoes alone. The ankle-foot orthoses included solid, articulated ankle, and posterior leaf-spring types. Evaluation measures included computerized gait analysis, Energy Efficiency Index data, and individual preference. Highly significant kinematic differences were found at the ankle with shoes alone approaching normative data and braces showing abnormal dorsiflexion. No significant differences, were found in velocity, cadence, stride length, or in the Energy Efficiency Index. Eight children preferred articulated braces, six chose posterior leaf-spring, and none chose the solid brace.