Cost-minimization analysis of sequential genetic testing versus targeted next-generation sequencing gene panels in patients with pheochromocytoma and paraganglioma.

INTRODUCTION: Pheochromocytomas and paragangliomas (PPGLs) are highly heritable tumours, with up to 40% of cases carrying germline variants. Current guidelines recommend genetic testing for all patients with PPGLs. Next-generation sequencing (NGS) enables accurate, fast, and inexpensive genetic testing. This study aimed to compare the costs related to PPGL genetic testing between the sequential testing using the decisional algorithm proposed in the 2014 Endocrine Society guidelines and targeted NGS gene panels. METHODS: Patients with proven PPGLs were enrolled. A gene list covering 17 susceptibility genes related to hereditary PPGLs was developed for targeted sequencing. Validation was carried out by Sanger sequencing. We simulated the diagnostic workflow to examine the anticipated costs based on each strategy for genetic testing. RESULTS: Twenty-nine patients were included, among whom a germline variant was identified in 34.5%. A total of 22.7% with apparently sporadic PPGL carried a variant. Five genes were involved (RET, n = 3; SDHB, n = 3; SDHD, n = 2; EGLN1, n = 1; and NF1, n = 1). According to the diagnostic workflow, the average cost of the targeted NGS (534.7 US dollars per patient) is lower than that of the sequential testing (734.5 US dollars per patient). The targeted NGS can also reduce the number of hospital visits from 4.1 to 1 per person. The cost can be further reduced to 496.24 US dollars per person (32% reduction) if we apply a new syndromic-driven diagnostic algorithm to establish priorities for specific genetic testing for syndromic and selected cases, and targeted NGS for non-syndromic patients. CONCLUSIONS: Targeted NGS can reduce both the cost of PPGL genetic testing and the number of hospital visits, compared with the conventional approach. Our proposed algorithm is the preferred approach due to its significant reduction of the cost of genetic testing.Key messagePheochromocytomas and paragangliomas are highly heritable neoplasms.The targeted next-generation sequencing (NGS) gene panels have proven to be fast, accurate, and inexpensive for the genetic analysis.According to this cost analysis, it is economically reasonable to use targeted NGS gene panels for genetic screening.

Noonan syndrome, metabolic syndrome and stroke-in-the-young: coincidence, causal or contribution?

A 34-year-old Thai woman developed acute left hemiparesis with dysarthria from subcortical infarction of the right MCA territory eighteen months after being diagnosed with Noonan syndrome, diabetes mellitus, dyslipidaemia, and hypertension. Further investigations suggested atherosclerosis as a cause. Modifying her risk factors was difficult, partly because of limited adherence. Three years later, she had another attack of ischaemic stroke in the same area. Unlike the three previously reported cases, the causation of strokes in this patient appeared to be a more 'complex' interaction between genetic defect and environment including possible subtle arterial abnormalities, metabolic risk factors, and mental insufficiency.

Congestive heart failure with rhabdomyolysis and acute renal failure in a manifesting female carrier of Duchenne muscular dystrophy with duplication of dystrophin gene.

We report a 69-year-old woman who presented with dyspnea, orthopnea, and acute renal failure. She also had proximal muscle weakness suggestive of muscle disease. Her symptoms were alleviated by induced dieresis, although there was high-serum creatine kinase. Investigations for any possible etiologies of rhabdomyolysis were all negative. An X-linked recessive muscle disease was highly suspicious in view of the fact that both of her sons had suffered from muscle disease and died of respiratory failure at the ages of 22 and 29, respectively. Her muscle biopsy showed mosaic pattern with dystrophin antibody against amino-terminal, carboxy-terminal, and rod domain. Her DNA study revealed heterozygous duplication at exon 1 to 6 of the dystrophin gene as well. Therefore, she is a manifesting carrier of dystrophinopathy who was first diagnosed in late adulthood with congestive heart failure, acute episode of spontaneous rhabdomyolysis, and acute renal failure.