Joubert syndrome: genotyping a Northern European patient cohort.

Joubert syndrome (JBS) is a rare neurodevelopmental disorder belonging to the group of ciliary diseases. JBS is genetically heterogeneous, with >20 causative genes identified to date. A molecular diagnosis of JBS is essential for prediction of disease progression and genetic counseling. We developed a targeted next-generation sequencing (NGS) approach for parallel sequencing of 22 known JBS genes plus 599 additional ciliary genes. This method was used to genotype a cohort of 51 well-phenotyped Northern European JBS cases (in some of the cases, Sanger sequencing of individual JBS genes had been performed previously). Altogether, 21 of the 51 cases (41%) harbored biallelic pathogenic mutations in known JBS genes, including 14 mutations not previously described. Mutations in C5orf42 (12%), TMEM67 (10%), and AHI1 (8%) were the most prevalent. C5orf42 mutations result in a purely neurological Joubert phenotype, in one case associated with postaxial polydactyly. Our study represents a population-based cohort of JBS patients not enriched for consanguinity, providing insight into the relative importance of the different JBS genes in a Northern European population. Mutations in C5orf42 are relatively frequent (possibly due to a Dutch founder mutation) and mutations in CEP290 are underrepresented compared with international cohorts. Furthermore, we report a case with heterozygous mutations in CC2D2A and B9D1, a gene associated with the more severe Meckel-Gruber syndrome that was recently published as a potential new JBS gene, and discuss the significance of this finding.

Clinical and molecular characterization of an infant with a tandem duplication and deletion of 19p13.

Copy number variations (CNVs) on the short arm of chromosome 19 are relatively rare. We present a patient with a tandem de novo 3.9 Mb duplication of 19p13.12p13.2 and an adjacent 288 kb deletion of 19p13.12. The CNVs were detected by genome wide SNP-array and confirmed by fluorescence in situ hybridization. Mate-pair sequencing revealed two breakpoint junctions leading to a germline tandem inverted duplication and an adjacent deletion. The patient had a major congenital heart defect and refractory edema leading to metabolic and endocrinological disturbances. Further complications occurred due to refractory chylothorax, severe inflammatory response syndrome, and repeating sepsis. After 2 months, the child died due to intractable respiratory failure. The phenotype of this patient was compared with reported patients with overlapping deletions or duplications. We conclude that the congenital heart defect, respiratory insufficiency, and abnormal neurologic examination are most likely due the contiguous gene deletion/duplication.

Recurrence risk after anticoagulant treatment of limited duration for late, second venous thromboembolism.

Patients with a second venous thromboembolism generally receive anticoagulant treatment indefinitely, although it is known that the recurrence risk diminishes over time while the risk of hemorrhage persists with continued anticoagulation and increases with age. Based on these arguments and limited evidence for indefinitely prolonged treatment, the Dutch guidelines recommend considering treatment of a limited duration (i.e. 12 months) for a 'late' second venous thromboembolism, defined by a second venous thromboembolism diagnosed more than 1 year after discontinuing treatment for a first event. It is hypothesized that the risk of continued anticoagulation might outweigh the benefits in such circumstances. We evaluated this management in daily practice. Since 2003, limited duration of treatment was systematically considered at our hospital in consecutive patients, in whom we determined the recurrence risk. Of 131 patients with late second venous thromboembolism, 77 were treated for a limited duration, of whom 26 developed a symptomatic third venous thromboembolism thereafter during a cumulative follow-up of 277 years, resulting in an incidence rate of 9.4/100 patient-years (95% confidence interval: 6.1-14). The incidence rates in patients with unprovoked and provoked venous thromboembolism were 12/100 patient-years (95% confidence interval: 7.4-19) and 5.6/100 patient-years (95% confidence interval: 2.2-12), respectively [adjusted hazard ratio 2.8 (95% confidence interval: 1.1-7.2)]. The recurrence risk after treatment of limited duration for 'late' second venous thromboembolism exceeded the risk of hemorrhage associated with extended anticoagulation. Most patients may, therefore, be better served by treatment of indefinite duration, although the risk-benefit ratio of extended anticoagulation should be weighed for every patient.

Impact of delay in clinical presentation on the diagnostic management and prognosis of patients with suspected pulmonary embolism.

RATIONALE: The nonspecific clinical presentation of pulmonary embolism (PE) frequently leads to delay in its diagnosis. OBJECTIVES: This study aimed to assess the impact of delay in presentation on the diagnostic management and clinical outcome of patients with suspected PE. METHODS: In 4,044 consecutive patients with suspected PE, patients presenting more than 7 days from the onset of symptoms were contrasted with those presenting within 7 days as regards the safety of excluding PE on the basis of a clinical decision rule combined with D-dimer testing. Patients were followed for 3 months to assess the rates of recurrent venous thromboembolism and mortality. MEASUREMENTS AND MAIN RESULTS: A delayed presentation (presentation >7 d) was present in 754 (18.6%) of the patients. The failure rate of an unlikely clinical probability and normal D-dimer test was 0.5% (95% confidence interval [CI], 0.01-2.7) for patients with and 0.5% (95% CI, 0.2-1.2) for those without diagnostic delay. D-dimer testing yielded a sensitivity of 99% (95% CI, 96-99%) and 98% (95% CI, 97-99%) in these groups, respectively. Patients with PE with diagnostic delay more frequently had centrally located PE (41% vs. 26%; P < 0.001). The cumulative rates of recurrent venous thromboembolism (4.6% vs. 2.7%; P = 0.14) and mortality (7.6% vs. 6.6%; P = 0.31) were not different for patients with and without delayed presentation. CONCLUSIONS: PE can be safely excluded based on a clinical decision rule and D-dimer testing in patients with a delayed clinical presentation. A delayed presentation for patients who survived acute PE was associated with a more central PE location, although this did not affect the clinical outcome at 3 months.