Karan Rai

Expanding the clinical phenotype of hereditary BAP1 cancer predisposition syndrome, reporting three new cases

The clinical phenotype of BAP1 hereditary cancer predisposition syndrome (MIM 614327) includes uveal melanoma (UM), cutaneous melanoma (CM), renal cell carcinoma (RCC), and mesothelioma. However, the frequency of the syndrome in patients with UM and the association with other cancers are still not clear. In this study, we screened 46 previously untested, unrelated UM patients with high risk for hereditary cancer for germline mutation in BAP1. We also studied four additional patients with a personal or family history suggestive of BAP1 hereditary cancer syndrome. We identified three patients with germline pathogenic mutations (c.2050 C>T, pGln684*; c.1182C>G, p.Tyr394*, and c.1882_1885delTCAC, p. Ser628Profs*8) in BAP1. Two of these three patients presented with UM and the third with a metastatic adenocarcinoma likely from a hepatic cholangiocarcinoma. Reported family histories included UM, mesothelioma, RCC, CM, and several other internal malignancies. The results of this study confirm the association between germline BAP1 mutation and predisposition to UM, mesothelioma, CM and RCC. However, other cancers, such as cholangiocarcinoma and breast carcinoma may be part of the phenotype of this hereditary cancer predisposition syndrome. In addition, the results support the existence of other candidate genes in addition to BAP1 contributing to hereditary predisposition to UM.

Comprehensive review of BAP1 tumor predisposition syndrome with report of two new cases

The BRCA1‐associated protein‐1 (BAP1) tumor predisposition syndrome (BAP1‐TPDS) is a recently identified hereditary cancer syndrome. Germline mutations in this tumor suppressor gene predispose families to the development of various malignancies. The molecular functions of the gene as well as the clinical phenotype of the syndrome are still being clarified. We sought to conduct a comprehensive review of published research into BAP1‐TPDS to more thoroughly delineate the clinical implications of germline BAP1 mutations. We also report two additional families with germline BAP1 mutations. Current evidence demonstrates that germline BAP1 mutations predispose families to uveal melanoma, renal cell carcinoma, malignant mesothelioma, cutaneous melanoma, and possibly to a range of other cancers as well. Some of these cancers tend to be more aggressive, have a propensity to metastasize, and onset earlier in life in patients with BAP1 mutations as compared to non‐predisposed patients with equivalent cancers. Although further research is necessary, this information can aid in the management, diagnosis, and therapy of these patients and their families, and highlights the importance of genetic counseling.

Analysis of BAP1 Germline Gene Mutation in Young Uveal Melanoma Patients

Abstract Background: To evaluate the prevalence of BAP1 germline mutations in a series of young patients with uveal melanoma (UM), diagnosed before age 30. Materials and Methods: The study was carried out on 14 young uveal melanoma patients (average age 21.4 years, range 3 months to 29 years). Germline DNA was extracted from peripheral blood. BAP1 sequencing was carried out using direct sequencing of all exons and adjacent intronic sequences. We also tested for germline mutations in additional melanoma-associated candidate genes CDKN2A and CDK4 (exon 4). Results: We identified one patient with a pathogenic mutation (c. 1717delC, p.L573fs*3) in BAP1. This patient was diagnosed with UM at age 18 years and had a family history of a father with UM and a paternal grandfather with cancer of unknown origin. One additional patient had an intronic variant of uncertain significance (c.123-48T > G) in BAP1 while the remaining 12 patients had no alteration. None of the patients had CDKN2A or CDK4 (Exon 4) mutations. Family history was positive for a number of additional malignancies in this series, in particular for cutaneous melanoma, prostate, breast and colon cancers. There were no families with a history of mesothelioma or renal cell carcinoma. Conclusions: This study suggests that a small subset of patients with early onset UM has germline mutation in BAP1. While young patients with UM should be screened for germline BAP1 mutations, our results suggest that there is a need to identify other candidate genes which are responsible for UM in young patients.

Germline BAP1 alterations in familial uveal melanoma

Uveal melanoma (UM) is the most commonly diagnosed primary intraocular tumor in adults. Familial UM (FUM), defined as two or more family members diagnosed with UM, is rare and estimated at less than 1% of all UM. Currently, BAP1 is the only gene known to contribute significant risk for UM. In this study we aimed to estimate the frequency of BAP1 mutation in FUM and to characterize the family and personal histories of other cancers in these families. We identified 32 families with FUM, including seven families previously reported by our group. BAP1 mutation testing was carried out by direct sequencing of the coding exons and the adjacent untranslated regions of the gene. Germline deletion and duplication analysis of BAP1 was assessed by multiplex ligation‐dependent probe amplification (MLPA). Germline BAP1 mutations were found in 6/32 (19%) families. No deletions or duplications were identified in any of the 24 samples tested by MLPA. Combined with published studies, the frequency of BAP1 mutations was 14/64 (22%) in FUM. FUM families without BAP1 mutations have distinct family histories with high rates of prostate cancer in first‐ and second‐degree relatives. It is likely that additional genes conferring risk for FUM exist. It is important to understand key shared features of FUM to focus future research on identifying these additional tumor predisposition syndromes. Though BAP1 should be tested first in these families, FUM families without BAP1 mutation should be explored for additional predisposition genes.

Genetic markers of pigmentation are novel risk loci for uveal melanoma

While the role of genetic risk factors in the etiology of uveal melanoma (UM) has been strongly suggested, the genetic susceptibility to UM is currently vastly unexplored. Due to shared epidemiological risk factors between cutaneous melanoma (CM) and UM, in this study we have selected 28 SNPs identified as risk variants in previous genome-wide association studies on CM or CM-related host phenotypes (such as pigmentation and eye color) and tested them for association with UM risk. By logistic regression analysis of 272 UM cases and 1782 controls using an additive model, we identified five variants significantly associated with UM risk, all passing adjustment for multiple testing. The three most significantly associated variants rs12913832 (OR = 0.529, 95% CI 0.415–0.673; p = 8.47E-08), rs1129038 (OR = 0.533, 95% CI 0.419–0.678; p = 1.19E-07) and rs916977 (OR = 0.465, 95% CI 0.339–0.637; p = 3.04E-07) are correlated (r2 > 0.5) and map at 15q12 in the region of HERC2/OCA2, which determines eye-color in the human population. Our data provides first evidence that the genetic factors associated with pigmentation traits are risk loci of UM susceptibility.

Germline BAP1 mutations misreported as somatic based on tumor-only testing.

We present three unrelated patients with germline mutations in BAP1 misreported as somatic mutations. All had strong family histories of cancer. One of these patients presented with an invasive breast cancer with the tumor tissue showing partial loss of the mutant rather than the wild type allele, suggesting that the germline BAP1 mutation didn’t contribute to breast cancer development in this patient. This data highlights the importance of sequencing matching germline and tumor DNA for proper assessment of somatic versus germline mutation status. In patients with somatic mutations reported from laboratories carrying out tumor-only genomic testing, the possibility that a variant may be a germline mutation should be considered, especially if the personal and/or family history suggests hereditary cancer predisposition. Since tumor-only testing can reveal germline mutations, ethical issues for patients being tested should be considered including proper consent and genetic counseling.