2 research outputs found
Heterogeneous genetic background of Hungarian patients with pheochromocytoma/paraganglioma requires gene panel testing
Introduction
Pheochromocytomas and paragangliomas (Pheo/PGL) are rare neuroendocrine
tumours arising from the adrenal medulla or the symphathetic paraganglia,
respectively. Germline mutations are present in w40% of the patients. To date, at
least 16 genes have been demonstrated to be involved in the genetic background
of Pheo/PGL. Prioritization in order of genes tested can be applied, but if the
probability of a disease-associated germline mutation exceeds 10% the testing of
all susceptibility genes is recommended. Using next generation sequencing
(NGS) based methods for genetic testing of Pheo/PGL associated genes
progressively becomes part of the routine diagnostics.
Objective
To assess the genetic background of Hungarian patients with Pheo/PGL and to
develop a NGS based gene panel assay for analysis of Pheo/PGL susceptibility
genes.
Methods
We examined 131 patients with the diagnosis of Pheo/PGL diagnosed and nursed
at the 2nd Department of Medicine, Semmelweis University. The prevalence of
the germline mutations of Pheo/PGL genes was determined using conventional
methods. Genotype-phenotype correlations were evaluated. A gene panel
covering 15 genes (RET, VHL, NF1, EPAS, EGLN1, KIF1B, SDHA, SDHB,
SDHAF2, SDHC, SDHD, FH, MAX, TMEM127, MEN1) was developed and
analytical sensitivity was evaluated on 36 patients with known genetic
background. Library preparation was performed using SeqCapEZ capture
platform with our probe design. Illumina MiSeq instrument was used for
sequencing. Sequencing data were analysed with GATK workflow. Variant
annotation was performed with SNPeffect.
Results
Germline mutations of Pheo/PGL genes were present in at 34% of the patients: 10
(7.6%) SDHB, 9 (6.9%) RET, 5 (3.8%) VHL, TMEM127, MDH2, 4 (3%) NF1, 3
(2.3%) SDHD, 2 (1.5%) SDHC and KIF1B. 5 of 10 SDHB mutation carriers
developed malignant disease. Homozygous form of a MDH2 variant was
associated with malignancy. Among the 10 patients with bilateral adrenal Pheo 4
RET, 2 TMEM127 and 1 VHL mutations were identified. The coverage of genes in
our panel was higher than 150 reads in all regions and all known mutations were
correctly identified.
Discussion
Our findings regarding the prevalence of germline mutations in the development
of Pheo/PGL are in accordance with the literature. No founder mutation occurred
in our population as we could detect mutations in 9 genes, underlining the need of
novel methods for mutation analysis in everyday clinical practice. Our NGSbased
gene panel performed accurately, however two recently identified genes
(MDH2, GOT2) were not covered