Mutation of the proline P81 into a serine modifies the tumour suppressor function of the von Hippel-Lindau gene in the ccRCC

BACKGROUND

The von Hippel-Lindau disease is an autosomal dominant syndrome associated with tumour formation in various tissues, such as retina, central nervous system, kidney, and adrenal glands. VHL gene deletion or mutations support the development of various cancers. Unclassified VHL variants also referred as "of unknown significance" result from gene mutations that have an unknown or unclear effect on protein functions. The P81S mutation has been linked to low penetrance Type 1 disease but its pathogenic function was not clearly determined.

METHODS

We established a stable cell line expressing the pVHL213 (c.241C>T, P81S) mutant. Using biochemical and physiological approaches, we herein analysed pVHL folding, stability and function in the context of this VHL single missense mutation.

RESULTS

The P81S mutation mostly affects the non-canonical function of the pVHL protein. The cells expressing the pVHL213P81S acquire invasive properties in relation with modified architecture network.

CONCLUSION

We demonstrated the pathogenic role of this mutation in tumour development in vhl patients and confirm a medical follow up of family carrying the c.241C>T, P81S.

Germline mutations in the new E1' cryptic exon of the VHL gene in patients with tumours of von Hippel-Lindau disease spectrum or with paraganglioma

BACKGROUNDS

The incidence of germline mutations in the newly discovered cryptic exon (E1') of VHL gene in patients with von Hippel-Lindau (VHL) disease and in patients with paraganglioma or pheochromocytoma (PPGL) is not currently known.

METHODS

We studied a large international multicentre cohort of 1167 patients with a previous negative genetic testing. Germline DNA from 75 patients with a single tumour of the VHL spectrum ('Single VHL tumour' cohort), 70 patients with multiple tumours of the VHL spectrum ('Multiple VHL tumours' cohort), 76 patients with a VHL disease as described in the literature ('VHL-like' cohort) and 946 patients with a PPGL were screened for E1' genetic variants.

RESULTS

Six different genetic variants in E1' were detected in 12 patients. Two were classified as pathogenic, 3 as variants of unknown significance and 1 as benign. The rs139622356 was found in seven unrelated patients but described in only 16 patients out of the 31 390 of the Genome Aggregation Database (p<0.0001) suggesting that this variant might be either a recurrent mutation or a modifier mutation conferring a risk for the development of tumours and cancers of the VHL spectrum.

CONCLUSIONS

VHL E1' cryptic exon mutations contribute to 1.32% (1/76) of 'VHL-like' cohort and to 0.11% (1/946) of PPGL cohort and should be screened in patients with clinical suspicion of VHL, and added to panels for Next Generation Sequencing (NGS) diagnostic testing of hereditary PPGL. Our data highlight the importance of studying variants identified in deep intronic sequences, which would have been missed by examining only coding sequences of genes/exomes. These variants will likely be more frequently detected and studied with the upcoming implementation of whole-genome sequencing into clinical practice.

[Extension of the thoracodorsal artery perforator flap's pedicle: Anatomical study]

PURPOSE

In recent years, the indications of latissimus dorsi myocutaneous flap decreased in favor of its version preserving muscle: the thoracodorsal artery perforator flap (TDAP). The intramuscular dissection reduce donor site morbidity but also allows an extension of the pedicle compared to conventional latissimus dorsi flap pedicle. The purpose of this study was to quantify objectively elongation of the pedicle when the perforator is dissected through the muscle.

METHOD

Sixteen TDAP flap were dissected in 9 cadavers. The pedicle was divided into 4 distinct parts: (1) hypodermis, (2) subcutaneous fat, (3) intramuscular, (4) conventional pedicle.

RESULTS

The length of the pedicle is significantly increased when the pedicle is dissected through the muscle. This extends the theoretical length from 5.25cm up to 9.19cm if the dissection is extended to the deep fat. Indeed, this results in a potentially exploitable TDAP pedicle length of 20.66cm.

CONCLUSION

The dissection of the perforator allows an extension of the pedicle of about 5 or 9cm if we continue the dissection in the subcutaneous fat. A long pedicle may be interesting in lower limb reconstructive surgery and facial reconstruction where microsurgery is not feasible.