Abstract
Hereditary papillary renal cell carcinoma (HPRCC) is a rare inherited
renal cancer syndrome characterized by bilateral and multifocal
papillary type 1 renal tumors (PRCC1). Activating germline pathogenic
variants of MET gene were identified in HPRCC families. We
reviewed the medical and molecular records of a large French series of
158 patients screened for MET oncogenic variants (153 index-cases
and five relatives). MET pathogenic variant rate was 10.4%
(16/153) with 37.5% among patients with familial PRCC1 and 3.3% among
patients with sporadic PRCC1 presentation. The phenotype in MET
mutated cases was characteristic as PRCC1 tumors were mainly bilateral
(82.3%) and multifocal (85.8%). Histologically, six out of seven
patients with MET germline pathogenic variant harboured biphasic
squamoid alveolar PRCC. Genetic screening identified in four index-cases
a novel missense pathogenic variant within the tyrosine kinase domain:
MET c.3389T>C, p.(Leu1130Ser). Functional assay
confirmed its oncogenic effect with a constitutive phosphorylation of
ERK protein and an abnormal focus formation induced. The
genotype-phenotype correlation between MET pathogenic variants
and PRCC1 presentation should encourage to widen the screening,
especially toward non-familial PRCC1. This precise phenotype also
constitutes a strong argument for the classification of novel missense
variants within the tyrosine kinase domain when functional assays aren’t
accessible.