Large Germline Deletions of Mitochondrial Complex II Subunits SDHB and SDHD in Hereditary Paraganglioma

Abstract

More than 30% of adrenal pheochromocytomas are hereditary. These neuroendocrine tumors are major components of three inherited cancer syndromes: multiple endocrine neoplasia type 2, von Hippel-Lindau disease (VHL), and pheochromocytoma/paraganglioma syndrome (PC/PGL). Germline mutations in RET; VHL; and SDHB, SDHC, and SDHD are associated with multiple endocrine neoplasia type 2, VHL, and PC/PGL, respectively. The majority (>70%) of hereditary extraadrenal PCs [catecholamine-secreting paragangliomas (PGL)] are accounted for by germline intragenic mutations in SDHB, SDHC, or SDHD. Therefore, a subset of hereditary PGL is not accounted for. Here we report two unrelated hereditary PGL families, one with a germline whole-gene deletion of SDHD (family 4194), the other a partial deletion of SDHB (family BRZ01). Although they were initially designated mutation negative for all of the PC-associated genes after PCR-based analysis, we suspected that a large deletion or rearrangement might be present. Genotyping around the PC-associated genes demonstrated that both families were consistent with linkage with one of these genes. Using fine structure genotyping and semiquantitative duplex PCR analysis, we identified an approximately 96-kb deletion spanning SDHD in family 4194 and an approximately 1-kb deletion involving the 5' end of SDHB in family BRZ01. Thus, including SDHB and SDHD deletion analysis could increase gene-testing sensitivity for PGL patients, which would aid in genetic counseling and management of patients and families.

Consensus Statement on next-generation-sequencing-based diagnostic testing of hereditary phaeochromocytomas and paragangliomas

“…This analysis should not only include sequence evaluation of coding regions and exon-intron boundaries of target genes, but also large indels or gene rearrangements. These grosser defects, which have been reported in the VHL, SDH and MAX genes [39][40][41][42] , might not be identifiable by WES performed at average depth of coverage. Instead, other…”

Clinical and molecular genetics of patients with the Carney–Stratakis syndrome and germline mutations of the genes coding for the succinate dehydrogenase subunits SDHB, SDHC, and SDHD

“…For the single patient in whom SDHB was deleted (CTRS20; Table 1), confirmation of the hemizygous deletion was performed with semi-quantitative duplex PCR of each SDHB exon compared to the housekeeping GAPDH exon 8 gene sequence using a method that we have reported elsewhere. 16 For the experiments reported here, 20 ng of genomic DNA was used as template for each semi-quantitative PCR reaction with primers flanking each SDHB exon and those of GAPDH exon 8 ( Table 2) using Qiagen HotStartTaq kit (Qiagen) and 30 cycles with an annealing temperature of 551C.…”

A Large Deletion in the Succinate Dehydrogenase B Gene (SDHB) in a Japanese Patient with Abdominal Paraganglioma and Concomitant Metastasis

“…while the majority of patients undergoing SDHB mutation analysis have missense and nonsense mutations, some mutation negative patients have been reported to carry either large partial or total deletions of the SDHB gene [10][11][12][13][14][15][16][17][18]. to investigate this possibility, we carried out MLPA and identified a heterozygous SDHB gene deletion encompassing sequences corresponding to the promoter region, exon 1 and exon 2 ( Fig.…”

“…Since large deletions are rare and are undetectable using this method, neither the frequency nor the clinical manifestation associated with large SDHB deletions is well known. recently, in addition to these mutations, the use of methods such as multiplex ligation-dependent probe amplification (MLPA) and quantitative multiplex PCR of short fluorescent fragments (QmPSF) have resulted in increased reports of large SDHB deletions [10][11][12][13][14][15][16][17][18].…”