Evidence for a Founder Effect of SDHB Exon 1 Deletion in Brazilian Patients With Paraganglioma.

CONTEXT: Limited information is available concerning the genetic spectrum of pheochromocytoma and paraganglioma (PPGL) patients in South America. Germline SDHB large deletions are very rare worldwide, but most of the individuals harboring the SDHB exon 1 deletion originated from the Iberian Peninsula. OBJECTIVE: Our aim was to investigate the spectrum of SDHB genetic defects in a large cohort of Brazilian patients with PPGLs. METHODS: Genetic investigation of 155 index PPGL patients was performed by Sanger DNA sequencing, multiplex ligation-dependent probe amplification, and/or target next-generation sequencing panel. Common ancestrality was investigated by microsatellite genotyping with haplotype reconstruction, and analysis of deletion breakpoint. RESULTS: Among 155 index patients, heterozygous germline SDHB pathogenic or likely pathogenic variants were identified in 22 cases (14.2%). The heterozygous SDHB exon 1 complete deletion was the most frequent genetic defect in SDHB, identified in 8 out of 22 (36%) of patients. Haplotype analysis of 5 SDHB flanking microsatellite markers demonstrated a significant difference in haplotype frequencies in a case-control permutation test (P = 0.03). More precisely, 3 closer/informative microsatellites were shared by 6 out of 8 apparently unrelated cases (75%) (SDHB-GATA29A05-D1S2826-D1S2644 | SDHB-186-130-213), which was observed in only 1 chromosome (1/42) without SDHB exon 1 deletion (X2 = 29.43; P < 0.001). Moreover, all cases with SDHB exon 1 deletion had the same gene breakpoint pattern of a 15 678 bp deletion previously described in the Iberian Peninsula, indicating a common origin. CONCLUSION: The germline heterozygous SDHB exon 1 deletion was the most frequent genetic defect in the Brazilian PPGL cohort. Our findings demonstrated a founder effect for the SDHB exon 1 deletion in Brazilian patients with paragangliomas.

Genetic and clinical aspects of paediatric pheochromocytomas and paragangliomas.

OBJECTIVE: Few and conflicting reports have characterized the genetics of paediatric pheochromocytomas and paragangliomas (PPGLs). This study aimed to investigate the clinical and genetic features of Brazilian children with PPGL. PATIENTS AND METHODS: This study included 25 children (52% girls) with PPGL. The median age at diagnosis was 15 years (4-19). The median time of follow-up was 145 months. The genetic investigation was performed by Sanger DNA sequencing, multiplex ligation-dependent probe amplification and/or target next-generation sequencing panel. RESULTS: Of the 25 children with PPGL, 11 (44%), 4 (16%), 2 (8%), 1 (4%) and 7 (28%) had germline VHL pathogenic variants, SDHB, SDHD, RET and negative genetic investigation, respectively. Children with germline VHL missense pathogenic variants were younger than those with SDHB or SDHD genetic defects [median (range), 12 (4-16) vs. 15.5 (14-19) years; P = .027]. Moreover, 10 of 11 cases with VHL pathogenic variants had bilateral pheochromocytoma (six asynchronous and four synchronous). All children with germline SDHB pathogenic variants presented with abdominal paraganglioma (one of them malignant). The two cases with SDHD pathogenic variants presented with head and neck paraganglioma. Among the cases without a genetic diagnosis, 6 and 2 had pheochromocytoma and paraganglioma, respectively. Furthermore, metastatic PPGL was diagnosed in four (16%) of 25 PPGL. CONCLUSIONS: Most of the paediatric PPGL were hereditary and multifocal. The majority of the affected genes belong to pseudohypoxic cluster 1, with VHL being the most frequently mutated. Therefore, our findings impact surgical management and surveillance of children with PPGL.

New Insights Into Pheochromocytoma Surveillance of Young Patients With VHL Missense Mutations.

CONTEXT: Von Hippel-Lindau (VHL) disease is an autosomal dominant syndrome caused by germline mutations in the VHL gene. Guidelines recommend pheochromocytoma (PHEO) biochemical screening should start at age 5 years. OBJECTIVE: Genotype-phenotype correlations in VHL, focusing on PHEO penetrance in children, were studied. DESIGN: We retrospectively evaluated 31 individuals (median age at diagnosis was 26 years) with diagnosed VHL disease. RESULTS: PHEO was diagnosed in six children with VHL. A large PHEO (5 cm) was detected in a 4-year-old boy with p.Gly114Ser mutation. PHEO penetrance was 55% starting at age 4 years. VHL missense mutations were identified in 11 of 22 families (50%), frameshift mutations in four (18.2%), stop codon in three (13.6%), splicing site in two (9.1%), and large gene deletion in two (9.1%). The codon 167 (n = 10) was a hotspot for VHL mutations and was significantly associated with PHEO (90% vs. 38%; P = 0.007). PHEOs and pancreatic neuroendocrine tumors (PNETs) were strongly associated with VHL missense mutations compared with other mutations (89.5% vs. 0% and 73.7% vs. 16.7%; P = 0.0001 and 0.002, respectively). In contrast, pancreatic cysts (91.7% vs. 26.3%; P = 0.0001), renal cysts (66.7% vs. 26.3%; P = 0.027), and central nervous system hemangioblastomas (91.7% vs. 47.3%; P = 0.012) were more frequent in VHL with nonmissense mutations. CONCLUSION: VHL missense mutations were highly associated with PHEO and PNETs. Our data support that in children with VHL harboring missense mutations, biochemical screening for PHEO should be initiated at diagnosis.

KCNJ5 Somatic Mutation Is a Predictor of Hypertension Remission After Adrenalectomy for Unilateral Primary Aldosteronism.

CONTEXT: Primary aldosteronism (PA) is the most common cause of endocrine hypertension (HT). HT remission (defined as blood pressure <140/90 mm Hg without antihypertensive drugs) has been reported in approximately 50% of patients with unilateral PA after adrenalectomy. HT duration and severity are predictors of blood pressure response, but the prognostic role of somatic KCNJ5 mutations is unclear. OBJECTIVE: To determine clinical and molecular features associated with HT remission after adrenalectomy in patients with unilateral PA. METHODS: We retrospectively evaluated 100 patients with PA (60 women; median age at diagnosis 48 years with a median follow-up of 26 months). Anatomopathological analysis revealed 90 aldosterone-producing adenomas, 1 carcinoma, and 9 unilateral adrenal hyperplasias. All patients had biochemical cure after unilateral adrenalectomy. KCNJ5 gene was sequenced in 76 cases. RESULTS: KCNJ5 mutations were identified in 33 of 76 (43.4%) tumors: p.Gly151Arg (n = 17), p.Leu168Arg (n = 15), and p.Glu145Gln (n = 1). HT remission was reported in 37 of 100 (37%) patients. Among patients with HT remission, 73% were women (P = 0.04), 48.6% used more than three antihypertensive medications (P = 0.0001), and 64.9% had HT duration <10 years (P = 0.0015) compared with those without HT remission. Somatic KCNJ5 mutations were associated with female sex (P = 0.004), larger nodules (P = 0.001), and HT remission (P = 0.0001). In multivariate analysis, only a somatic KCNJ5 mutation was an independent predictor of HT remission after adrenalectomy (P = 0.004). CONCLUSION: The presence of a KCNJ5 somatic mutation is an independent predictor of HT remission after unilateral adrenalectomy in patients with unilateral PA.