Rare occurrence of PHOX2b mutations in sporadic neuroblastomas.

Neuroblastomas (NBs) are frequent solid tumors in childhood for which no specific genetic marker linked to their development has been identified to date. PHOX2b, which regulates the autonomic neuron development, has been associated with the development of autonomic diseases, and has been considered a potential candidate gene for neural crest-derived tumors such as NB. To ascertain the role of the PHOX2b gene in NB development, we have sequenced the complete PHOX2b coding region in tumors from 69 patients with sporadic NB, while 130 blood donors served as negative controls and 9 NB cell lines as positive controls. We found a missense deletion in exon 3 in a cell line. A further silent mutation in exon 3 (c.870C>A) was observed in 3 tumors but in none of the controls. A new polymorphism in intron 1 (IVS1-114 G>A) was observed in 31 tumor samples (44.9%) and in 68 controls (52.3%). We did not find any conclusive association of the polymorphisms or mutations in PHOX2b with the development of NB, although the large confidence intervals neither substantiate nor exclude a role for this gene in the tumor etiology.

Ultrasound aided pin fixation of biodegradable osteosynthetic materials in cranioplasty for infants with craniosynostosis.

AIM: Biodegradable osteosynthesis materials are often used for fixation of bone fragments when repairing craniosynostoses. When compared with titanium plates they have the disadvantage of difficult handling and time-consuming thread cutting. A new method of using resorbable pins inserted with the aid of ultrasound (bone welding) and not requiring thread cutting was applied in patients for the first time. METHOD: In eight patients with craniosynostoses, the biodegradable material Resorb-X was fixed with resorbable pins inserted with the aid of ultrasound. The patients were followed up for 12 months. RESULTS: Pin fixation was stable in all cases. The time required for applying the osteosynthesis materials was reduced by about 50% since handling of the material was easier and no thread cutting was required. CONCLUSIONS: Due to fixation in cortical as well as cancellous bone ultrasound aided fixation using resorbable osteosynthesis materials is more stable than screw fixation. The time required for application is considerably shortened as no thread cutting is required.

Risk-inducing activities leading to injuries in a child and adolescent population of Germany.

BACKGROUND: Injuries are the most common cause of mortality in children, also accounting considerably for childhood morbidity. However, data on injuries only provide valid information on the actual risk of each injury-causing activity when taken in consideration of the relationship with actual activity exposure data. Therefore, the primary goal of this investigation is to determine the relative risk of normal child and adolescent activities. METHODS: From January 1, 1999 to December 31, 2001, a school questioning in regard to social, pedagogic, and leisure activities was performed among 2,325 students ranging from 6 to 17 years old. A total of 3,645 injuries sustained by children and adolescents treated at the surgical emergency department of the University Hospital Dresden were analyzed. Furthermore, a danger awareness test was performed. RESULTS: Forty-three percent of all injuries happened during leisure time, 41% at school, 8% in traffic, and 8% at home. Bicycle riding was pointed out as the most frequent leisure activity, regardless of gender and age. Horse riding had a 9-fold increased risk and moped driving had a 23.75-fold increased risk for injury compared with adolescent bike riding. Horse riding and snowboarding showed an increased risk for injury in children (5.6- and 4.2-fold, relative to biking). The level of danger awareness was significantly lower in children with a history of frequent injuries. CONCLUSIONS: The riskier activities were horse-riding, moped driving, and snowboarding. The level of danger awareness did affect the frequency of injuries. The authors recommend a danger awareness test for all children to identify those who would benefit from injury prevention training.

Mucoepidermoid carcinoma as an unusual cause for recurrent respiratory infections in a child.

Recurrent respiratory infections in a 9-year-old girl prompted a chest radiograph and a CT scan, which showed a right middle lobe consolidation. Bronchoscopy revealed a tumor that totally obstructed the middle lobe. Open lung biopsy revealed a low-grade mucoepidermoid carcinoma. Middle and lower right lung lobectomy was performed, followed by an uneventful recovery. Cytogenetic investigation of tumor cells exhibited the translocation t(11;19). This case shows that further diagnostic modalities such as CT scanning should be performed early in children with recurrent lower respiratory tract infections who have suspicious radiographic findings such as persistent atelectasis or recurrent unifocal infiltration. Bronchial mucoepidermoid carcinoma is infrequent, and molecular investigations might shed additional light on the prognosis.

Functional haplotypes of the RET proto-oncogene promoter are associated with Hirschsprung disease (HSCR).

The activation of the RET signaling pathway during embryogenesis is a crucial prerequisite for a directional migration of enteric nervous system progenitor cells. Loss-of-function germline mutations of the RET proto-oncogene are reported in familial and sporadic cases of Hirschsprung disease (HSCR) with a variable frequency. Furthermore, variants of several RET polymorphisms are over- or under-represented in HSCR populations. Specifically, the c.135A RET variant has been previously shown to be strongly associated with the HSCR phenotype. We have reported an HSCR-phenotype modifying effect of the RET c.135G>A polymorphism due to a within-gene interaction in patients harboring RET germline mutations, yet the function of the c.135G>A variant is unknown. The basic RET promoter region was investigated by DNA sequencing approach in 80 HSCR patients. Identified polymorphisms were genotyped in the HSCR and in a control population and haplotypes were reconstructed. The dual-luciferase assay was used to evaluate the activity of different RET promoter haplotypes. We demonstrate that variants of two RET promoter polymorphisms -5G>A and -1C>A from the transcription start site are associated with HSCR. Furthermore, the -5G>A polymorphism is in strong linkage disequilibrium with the c.135G>A polymorphism. The promoter haplotype -5/-1AC associated with HSCR has a significantly lower activity in an in vitro dual-luciferase expression assay compared with those haplotypes identified in the majority of normal controls. These data suggest a role for RET haplotypes containing the -5A promoter variant in the etiology of HSCR.

Novel intronic polymorphisms in the RET proto-oncogene and their association with Hirschsprung disease.

Germline mutations of the RET proto-oncogene have been found in familial and sporadic forms of Hirschsprung disease (HSCR), but also in the autosomal dominantly inherited multiple endocrine neoplasia type 2 (MEN2) syndromes, which comprise the medullary thyroid carcinoma (MTC) as an obligatory feature. Besides mutations various polymorphisms of the RET proto-oncogene are associated with the HSCR. In this study, we have characterized seven intronic RET polymorphisms (IVS2+9G>A, IVS4+48A>G, IVS12+47C>T, IVS14-24G>A, IVS19+47T>C, IVS20+96C>T, 3'UTR+124A>G) and investigated these variants by DNA sequencing in populations of 76 HSCR patients and 40 sporadic MTC patients as well as in a control population. Variants of four of these seven polymorphisms have a strong association with the HSCR phenotype. In contrast, none of the investigated polymorphisms show a significant difference in the genotype distribution and the allele frequencies in patients with sporadic MTC when compared to controls. These findings support the hypothesis that specific RET haplotypes cause or modify the HSCR phenotype.

Various penetrance of familial medullary thyroid carcinoma in patients with RET protooncogene codon 790/791 germline mutations.

OBJECTIVE: To describe a genotype-phenotype correlation in MEN2 families with germline mutations of codons 790/791 and discuss options for the therapeutic management of gene carriers. SUMMARY BACKGROUND DATA: Heredity of MEN2 syndromes is caused by a heterozygous germline mutation in the protooncogene. Rare mutations of codons 790/791 associated with incomplete penetrant MEN2A/FMTC phenotype were reported in five families, contraindicating the prophylactic thyroidectomy for the genetically affected children. METHODS: Forty-five patients with a putative sporadic MTC were screened for germline mutations by direct DNA sequencing. Family members of identified index cases underwent genetic analysis. Gene carriers were examined clinically and biochemically, and all gene carriers underwent prophylactic thyroidectomy. RESULTS: Five index patients were identified, four of whom harbored mutations in codons 790/791 and one in codon 634. In the kindreds, four L790F carriers and one Y791F carrier were detected. The thyroid gland histology of L790F carriers revealed medullary thyroid carcinoma in two patients (aged 29 and 50 years) and C-cell hyperplasia in two additional patients (aged 9 and 16 years). The Y791F carrier had a normal histology. CONCLUSIONS: Codon 790/791 mutations had diverse penetrance. Whereas prophylactic thyroidectomy in children is a justifiable approach for codon 790 mutation carriers, the indication for thyroidectomy should depend on the clinical course of codon 791 carriers.

Association between c135G/A genotype and RET proto-oncogene germline mutations and phenotype of Hirschsprung's disease.

BACKGROUND: Several genes, including the major susceptibility gene RET, have roles in development of Hirschsprung's disease. Results of genetic-linkage analysis of patients with familial disease with both long-segment and short-segment phenotypes have shown close linkage with the RET locus. We aimed to investigate whether both RET mutations and polymorphisms contribute to phenotype of Hirschsprung's disease. METHODS: We looked at the coding region of all 21 exons of the RET proto-oncogene, including the flanking intronic sequences, by direct DNA sequencing in 76 caucasians from Germany with Hirschsprung's disease. FINDINGS: 20 different mutations were detected in 18 patients. Mutations were under-represented in patients with a homozygous RET c135A/A genotype in association with short-segment phenotype. Short-segment phenotype also arose if the RET mutation was on the c135A allele; conversely, a RET germline mutation on the c135G allele resulted in long-segment phenotype, particularly in heterozygous c135G/A patients. INTERPRETATION: These observations lend support to the idea that both RET alleles have a role in pathogenesis of Hirschsprung's disease, in a dose-dependent fashion. We also showed that the c135G/A polymorphism modifies the phenotype by a within-gene interaction between the c135A variant and a mutation.