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Pertesi M, Konstantopoulou I, Yannoukakos D. Haplotype analysis of two recurrent genomic rearrangements in the BRCA1 gene suggests they are founder mutations for the Greek population. The deletions of 4.4 and 3.2 kb identified in exons 24 and 20, respectively, are two of the four most common mutations in the BRCA1 gene in Greek breast cancer patients. They have been reported previously six and three times, respectively, in unrelated Greek families. A total of 11 more families have been identified in the present study. In order to characterize these recurrent mutations as founder mutations, it is necessary to identify the disease-associated haplotype and prove that it is shared by all the mutation carriers, suggesting that it occurred only once in a common ancestor. Haplotype analysis was performed on 24 mutation carriers and 66 healthy individuals using 10 short tandem repeat markers located within and flanking the BRCA1 gene locus, spanning a 5.9 Mb interval. Results indicate that most of the carriers of the exon 24 deletion share a common core haplotype '4-7-6-6-1-3' between markers D17S951 and D17S1299, for a stretch of 2.9 Mb, while the common haplotype for the exon 20 deletion is '6-7-4-2-6-7-1-3' between markers D17S579 and D17S1299, for a stretch of 3.9 Mb. Both genomic rearrangements in BRCA1 gene are Greek founder mutations, as carriers share the same, for each mutation, disease-associated haplotype, suggesting the presence of a distinct common ancestor for both mutations. [ABSTRACT FROM AUTHOR]

Background: In most Western populations, 5-10% of all breast cancer cases can be attributed to major genetic factors such as predisposing mutations in BRCA1 and BRCA2, with early-onset cases generally considered as an indicator of genetic susceptibility. Specific BRCA1 and BRCA2 mutations or different mutation frequencies have been identified in specific populations and ethnic groups. Previous studies in Greek breast and/or ovarian cancer patients with family history have shown that four specific BRCA1 mutations, c.5266dupC, G1738R, and two large genomic rearrangements involving deletions of exons 20 and 24, have a prominent function in the population's BRCA1 and BRCA2 mutation spectrum.Methods: To estimate the frequency of the above mutations in unselected Greek breast cancer women, we screened 987 unselected cases independently of their family history, collected from major Greek hospitals.Results: Of the 987 patients, 26 (2.6%) were found to carry one of the above mutations in the BRCA1 gene: 13 carried the c.5266dupC mutation (1.3%), 6 carried the exon 24 deletion (0.6%), 3 carried the exon 20 deletion (0.3%), and 4 carried the G1738R mutation (0.4%). Among 140 patients with early-onset breast cancer (<40 years), 14 carried one of the four mutations (10.0%).Conclusion: These results suggest that a low-cost genetic screening for only the four prominent BRCA1 mutations may be advisable to all early-onset breast cancer patients of Greek origin. [ABSTRACT FROM AUTHOR]

National genetic variation registries vastly increase the level of detail for the relevant population, while directly affecting patient management. Herein, we report CanVaS, a Cancer Variation reSource aiming to document the genetic variation of cancer patients in Greece. CanVaS comprises germline genetic data from 7,363 Greek individuals with a personal and/or family history of malignancy. The data set incorporates approximately 24,000 functionally annotated rare variants in 97 established or suspected cancer susceptibility genes. For each variant, allele frequency for the Greek population, interpretation for clinical significance, anonymized family and segregation information, as well as phenotypic traits of the carriers, are included. Moreover, information on the geographic distribution of the variants across the country is provided, enabling the study of Greek population isolates. Direct comparisons between Greek (sub)populations with relevant genetic resources are supported, allowing fine-grain localized adjustment of guidelines and clinical decision-making. Most importantly, anonymized data are available for download, while the Leiden Open Variation Database schema is adopted, enabling integration/interconnection with central resources. CanVaS could become a stepping-stone for a countrywide effort to characterize the cancer genetic variation landscape, concurrently supporting national and international cancer research. The database can be accessed at: http://ithaka.rrp.demokritos.gr/CanVaS., (© 2021 Wiley Periodicals LLC.)

Germline BRCA1 and BRCA2 loss-of-function variants have been linked to increased breast and ovarian cancer risk, with more than 5,000 distinct pathogenic variants being reported worldwide. Among individuals of Greek descent, the BRCA1/2 variant spectrum is heterogeneous, but characterized by strong founder effects. As patients from certain geographical regions of Greece (like Crete) were underrepresented in previous studies, we hypothesized that isolated Cretans, a southern Greece islanders' population with distinct demographic, cultural and genetic features, could harbor founder BRCA1/2 mutations. A total of 304 breast or/and ovarian cancer patients of Cretan descent, fulfilling NCCN criteria for genetic testing, were tested by NGS or Sanger sequencing, followed by MLPA. Haplotype analysis was subsequently performed to investigate potential founder effects of recurrent alleles. Overall, 16.5% (50/304) of the tested patients carried 22 different pathogenic variants; 48% in BRCA1, 52% in BRCA2. Three variants, namely two in BRCA2 (Δexons 12 and 13 and c.7806-2A>T) and one in BRCA1 (c.5492del), constituting approximately half (48%) of all detected pathogenic variants, were shown to have a founder effect, with all carriers sharing common haplotypes. Remarkably, these variants were confined to Cretans and have not been identified in other regions of Greece. The high prevalence of specific BRCA1/2 pathogenic variants among Cretans, provides the possibility of cost- and time-efficient screening of the Cretan population. Integrating this knowledge in local public health services may have a significant impact on cancer prevention, and may serve as a starting point for the implementation of testing on a population level., (© 2020 UICC.)

Introduction: BRCA1/BRCA2 mutation carriers indefinitely comprise a distinct group of patients with breast cancer (BC), with their tumors displaying specific pathologic characteristics. Although these connections are known, they are not fully elucidated. We therefore sought to investigate the clinicopathologic characteristics and overall survival of Greek patients with BC carrying BRCA1/BRCA2 mutations., Patients and Methods: Greek patients with BC diagnosed between 1999 and 2016, fulfilling the National Comprehensive Cancer Network criteria for genetic testing, were analyzed for BRCA1/BRCA2 mutations by Sanger sequencing or by a 94-gene panel. Medical records and pathology reports were retrospectively reviewed to retrieve patient and tumor baseline characteristics. Potential associations with mutation status were assessed using the Fisher exact, Pearson χ 2 , and Mann-Whitney tests., Results: Of 2096 selected patients with BC, we identified 297 (14.2%) BRCA1 and 88 (4.2%) BRCA2 carriers. The mean age at BC diagnosis was 40 and 42.6 years, respectively (P = .02). Tumor histologic subtypes in BRCA1 and BRCA2 carriers were predominantly ductal (79%) followed by medullary (10%), and ductal (72%) followed by lobular (15%), respectively. A significantly higher percentage of BRCA2 tumors were human epidermal growth factor receptor 2-positive, compared with BRCA1 tumors (21.7% vs. 5.8%; P < .001). Second primary cancer diagnosis was more frequent in BRCA1 compared with BRCA2 mutation carriers (36.2% vs. 10.7%; P < .001), whereas there was no difference in 15-year overall survival (hazard ratio, 0.92; 95% confidence interval, 0.48-1.83; P = .804) between the 2 groups., Conclusions: These data confirm established observations in the pathology of BRCA-related tumors and provide further insight on the association of rare histologic entities with mutations in these genes, which can be clinically beneficial., (Copyright © 2019 Elsevier Inc. All rights reserved.)

Purpose: Multiple lines of evidence have suggested a likely causative role in breast/ovarian cancer (BrCa/OvCa) predisposition for the BRCA1 p.(Val1833Met) variant, predominantly found among Greek patients. Our aim was to study the variant's prevalence and founder effect on the Greek population, while providing additional data for its pathogenicity., Methods: We genotyped 3531 BrCa/OvCa patients using Sanger and next generation sequencing, as well as 1558 healthy, age-matched females with real-time PCR. Carriers underwent haplotype analysis to determine a founder effect. A co-segregation analysis was applied to estimate the likelihood ratio for pathogenicity., Results: In total, 27 BrCa/OvCa patients (0.77%; 27/3531) were found to carry the p.(Val1833Met) variant. No carriers were identified in the control group diagnosis. A common shared haplotype, spanning 2.76 Mb on chromosome 17 was demonstrated among carriers, establishing the founder effect. BRCA1, p.(Val1833Met) is possibly a disease-associated variant, supported by a likelihood ratio of 1.88, while a correlation to ovarian cancer is suspected., Conclusions: Altogether, BRCA1, p.(Val1833Met) variant is a Greek founder and is very likely to predispose for BrCa/OvCa. Therefore, such carriers should be counselled accordingly, with clinical recommendations supporting surveillance and risk-reduction strategies, while providing the option for targeted therapeutic interventions., (Copyright © 2019 Elsevier Inc. All rights reserved.)

PALB2 loss-of-function variants play an important role in breast, pancreatic and possibly, ovarian and gastric cancer susceptibility. Their frequency can be influenced by founder effects, already described in some populations. Herein, we have assessed the possible founder effect of PALB2 c.2257C>T (p.Arg753*) truncating variant among Greek breast cancer patients, while investigating possible correlations with cancer diagnoses. Following a lead deriving from a background study of highly selected Greek breast cancer patients, a total of 2496 breast and 697 ovarian cancer patients were directly genotyped for the PALB2 c.2257C>T truncating variant. Consequently, haplotype analysis was conducted on identified carriers, using seven microsatellite markers. The prevalence of the PALB2 variant was 0.24% (6/2496) and 0.14% (1/697) among breast and ovarian cases, respectively. Family history seems to be an important factor for the variant identification, although not reaching statistical significance. Microsatellite analysis on 12 carriers revealed a common shared haplotype, spanning a chromosomal region of ~1.2 Mb; the variant was possibly introduced in the Greek population ~1600 years ago. The variant confers high breast cancer risk, as illustrated by comparison with publicly available control groups. Genetic testing for PALB2, especially for the Greek founder c.2257C>T truncating variant, should be seriously considered in Greek breast cancer cases, since such findings could assist appropriate clinical management for the patients and their families.

Germline CHEK2 mutations confer increased cancer risk, for breast and other types, which is variable depending on the specific mutation. Of these, Large Genomic Rearrangements (LGRs) have been rarely reported; to date only eight LGRs have been published with just the Czech founder mutation, the deletion of exons 9 and 10, being molecularly characterized and studied extensively. The present study aimed to molecularly define and determine the contribution of two rare, apparently novel CHEK2 LGRs, among Greek breast cancer patients. These specifically involve a ~6 kb in-frame deletion of exons 2 & 3 that removes CHEK2's FHA domain and a ~7.5 kb in-frame deletion of exon 6, which removes an α-helix of CHEK2's kinase domain. The latter was identified in 5 out of 2355 (0.22%) patients tested, while haplotype analysis revealed a common disease-associated haplotype, suggesting a single common ancestor and a Greek founder. Although in-frame, this LGR is predicted to be damaging by a yeast-based functional assay and structure-function predictions. The present study highlights the existence of rare, population-specific, genomic events in a known breast cancer predisposing gene, which can explain a proportion of hereditary breast cancer. Identification of such mutation carriers is rather important since appropriate clinical actionability will be inferred.

Peutz-Jeghers syndrome (PJS) is a rare autosomal dominant disorder caused by germline mutations in the STK11 tumor suppressor gene. PJS patients face a cumulative cancer risk as high as 93% for all sites combined. The present study reports the spectrum of STK11 mutations in eight families with clinical diagnosis of PJS, summarizes the clinical characteristics of sixteen mutation carriers and launches a National Registry for PJS in Greece. STK11 loss-of-function (LoF) mutations were detected in 87.5% of index patients. Carriers presented with their first manifestation at a median age of 24.9 years, while early-onset breast cancer was the most frequent malignancy observed, highlighting the need for breast surveillance. Out of the deleterious STK11 mutations identified, two were novel: c.375&#95;376delGT and c.676&#95;679dupAACG, with 57.2% of these potentially occurring de novo. Using all available clinical and genetic data, the National Registry for Greek PJS was established in an attempt to better characterize the syndrome and raise awareness among patients and clinicians (available at https://www.peutzjeghersgreece.org). This is the first comprehensive genetic analysis and clinical characterization of Greek PJS patients, where a high incidence of breast cancer was observed and the first attempt to centralize all data in a National Registry., (Copyright © 2017 Elsevier Inc. All rights reserved.)

Purpose: BRCA mutation carriers can benefit from targeted clinical interventions. On the other hand, families with evident aggregation of breast cancer (BC) cases and a BRCA-negative genetic test can still be considered as of elevated risk, since the underlying genetic factor remains unidentified. In the present study, we compared clinical and demographic characteristics between BRCA1 mutation carriers (BRCA1mut) and non-carriers (non-BRCA1) in a Greek group of BC patients (n=321)., Methods: Data were collected and analyzed from 321 women with BC, with 131 patients screened for pathogenic mutations in the high-penetrant genes BRCA1 and BRCA2. Collected data included demographics, pedigrees, tumor histopathology and immunohistochemistry findings., Results: In BRCA1mut patients, their mothers and grand- mothers were diagnosed at a younger age compared to non-BRCA1-carriers. Additionally, BRCA1mut patients were diagnosed with mainly estrogen receptor (ER) negative (p<0.001), Her-2 negative (p<0.05) and triple negative (p<0.01) tumors. The youngest generation was diagnosed with familial breast cancer (FBC) 9.7 years earlier than their mothers (p<0.001). Age at BC diagnosis negatively correlated with the nuclear grade of breast tumors (r=-0.3, p<0.05). Among parous individuals, the number of full-term pregnancies significantly correlated with the age at BC onset (r=0.19, p<0.05)., Conclusion: Despite their similarities, FBC cases with identified BRCA1 mutations exhibit a clearly distinct profile. We have identified an anticipation effect in FBC patients, with significantly reduced age at diagnosis in younger generations. Increased parity seems to prevent early BC onset. This is the first study comparing clinical and demographic characteristics of FBC BRCA1mut and non-carriers in a Greek cohort.

The CHEK2 gene encodes a protein kinase that plays a crucial role in maintenance of genomic integrity and the DNA repair mechanism. CHEK2 germline mutations are associated with increased risk of breast cancer and other malignancies. From a clinical perspective, the most significant mutation identified is the c.1100delC mutation, which is associated with an approximately 25% lifetime breast cancer risk. The distribution of this mutation shows wide geographical variation; it is more prevalent in the Northern European countries and less common, or even absent, in Southern Europe. In order to estimate the frequency of the CHEK2 c.1100delC mutation in Greek breast cancer patients, we genotyped 2,449 patients (2,408 females and 41 males), which was the largest series ever tested for c.1100delC. The mean age of female and male breast cancer diagnosis was 49 and 59 years, respectively. All patients had previously tested negative for the Greek BRCA1 founder and recurrent mutations. The CHEK2 c.1100delC mutation was detected in 0.16% (4 of 2,408) of females, all of whom were diagnosed with breast cancer before the age of 50 years. Only one c.1100delC carrier was reported with breast cancer family history. The present study indicates that the CHEK2 c.1100delC mutation does not contribute substantially to hereditary breast cancer in patients of Greek descent., (Copyright © 2015 Elsevier Inc. All rights reserved.)

Currently, hereditary breast cancer is being attributed to more than 20 genes of differing penetrance. Although BRCA1 and BRCA2 are still the genes of reference for breast cancer susceptibility, extreme breast cancer phenotypes may be the result of deleterious alleles of other genes. Here, we report three families with early-onset breast cancer that were initially referred for BRCA1/BRCA2 genetic testing. They were diagnosed with breast cancer at an extraordinarily early age. On the basis of their extensive family history, which included multiple cancer types, and their Her2 status, they were suspected for Li-Fraumeni syndrome. Indeed, all three probands were found to harbor TP53 tumor suppressor gene mutations. These included p.C275X, described here for the first time, as well as p.R213X and p.Y220C, which have been described in the past. Our conclusion is that decisions on genetic analysis for inherited early onset breast cancer should always be based on detailed pedigree information, combined with Her2 status., (© 2014 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.)

We have screened 473 breast/ovarian cancer patients with family history, aiming to define the prevalence and enrich the spectrum of BRCA1/2 pathogenic mutations occurring in the Greek population. An overall mutation prevalence of 32% was observed. Six BRCA1 recurrent/founder mutations dominate the observed spectrum (58.5% of all mutations found). These include three mutations in exon 20 and three large genomic deletions. Of the 44 different deleterious mutations found in both genes, 16 are novel and reported here for the first time. Correlation with available histopathology data showed that 80% of BRCA1 carriers presented a triple-negative breast cancer phenotype while 82% of BRCA2 carriers had oestrogen receptor positive tumours. This study provides a comprehensive view of the frequency, type and distribution of BRCA1/2 mutations in the Greek population as well as an insight of the screening strategy of choice for patients of Greek origin. We conclude that the Greek population has a diverse mutation spectrum influenced by strong founder effects., (© 2013 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.)

Germline mutations in the BRCA1 and BRCA2 genes contribute to approximately 18% of hereditary ovarian cancers conferring an estimated lifetime risk from 15% to 50%. A variable incidence of mutations has been reported for these genes in ovarian cancer cases from different populations. In Greece, six mutations in BRCA1 account for 63% of all mutations detected in both BRCA1 and BRCA2 genes. This study aimed to determine the prevalence of BRCA1 mutations in a Greek cohort of 106 familial ovarian cancer patients that had strong family history or metachronous breast cancer and 592 sporadic ovarian cancer cases. All 698 patients were screened for the six recurrent Greek mutations (including founder mutations c.5266dupC, p.G1738R and the three large deletions of exon 20, exons 23-24 and exon 24). In familial cases, the BRCA1 gene was consequently screened for exons 5, 11, 12, 20, 21, 22, 23, 24. A deleterious BRCA1 mutation was found in 43/106 (40.6%) of familial cancer cases and in 27/592 (4.6%) of sporadic cases. The variant of unknown clinical significance p.V1833M was identified in 9/698 patients (1.3%). The majority of BRCA1 carriers (71.2%) presented a high-grade serous phenotype. Identifying a mutation in the BRCA1 gene among breast and/or ovarian cancer families is important, as it enables carriers to take preventive measures. All ovarian cancer patients with a serous phenotype should be considered for genetic testing. Further studies are warranted to determine the prevalence of mutations in the rest of the BRCA1 gene, in the BRCA2 gene, and other novel predisposing genes for breast and ovarian cancer.

127 Greek breast/ovarian cancer families were screened for germline BRCA1/2 mutations by dHPLC followed by direct sequencing. Our results indicated 16 and 5 breast/ovarian cancer families bearing deleterious mutations in the BRCA1 and BRCA2 genes, respectively. Two novel BRCA2 germline mutations (G4X and 3783del10) are reported here for the first time. Subsequent compilation of our present findings with previously reported mutation data reveals that in a total of 287 Greek breast/ovarian cancer families, 46 and 13 carry a deleterious mutation in BRCA1 and BRCA2, respectively. It should be noted that two BRCA1 mutations, 5382insC and G1738R, both located in exon 20, account for 46% of the families found to carry a mutation. Based on our mutation analysis results, we propose here a hierarchical, cost-effective BRCA1/2 mutation screening protocol for individuals of Greek ethnic origin. The suggested protocol can impact on the clinical management of breast-ovarian cancer families on a national healthcare system level.

The identification of genomic rearrangements in breast/ovarian cancer families has widened the mutational spectrum of the BRCA1 gene, increasing the number of patients who can benefit from molecular screening. More than 60 different BRCA1 genomic rearrangements with mapped breakpoints have been reported up to date, in all exons of the gene. The proportion of BRCA1 mutations due to genomic rearrangements varies from 8 to 27% in different populations, probably due to both ethnic diversity and the technical approach employed. In order to estimate the contribution of BRCA1 genomic rearrangements to hereditary breast/ovarian cancer (HBOC) predisposition in Greek families, probands from 95 families with breast/ovarian history but negative for point mutations or small insertions/deletions in BRCA1 and BRCA2 genes, were screened using Quantitative Multiplex PCR of Short Fluorescent Fragments (QMPSF). Two large deletions of 4.2 and 4.4 kb were identified in exons 20 and 24 respectively. Additional screening, using diagnostic primers for the above deletions in exons 20 and 24, performed on another 86 probands from families with breast/ovarian cancer history and 210 cases of sporadic breast/ovarian cancer resulted in the identification of two more large genomic rearrangements. One, identified in a familial case, identical to the previous exon 24 deletion and a second, identified in a case reported as sporadic, 3.2 kb deletion involving exon 20 and reported elsewhere in another Greek patient. Three out of four genomic rearrangements described in this study were detected in patients who had developed both breast and ovarian cancer; thus suggesting a correlation between the specific phenotype and the high probability of detecting inherited rearrangements in BRCA1.

Objective: Familial medullary thyroid carcinoma (FMTC) is caused by germ-line mutations in the RET proto-oncogene. These mutations concern mainly cysteine residues in exons 10 and 11, whereas noncysteine mutations in exons 13-16 are rare. Mutations in other exons have been reported only in isolated families. In this study we have analysed the RET gene in two FMTC families negative for mutations in the above exons., Design: We have analysed exons 7-19 and 21 in one index patient from each family using DNA sequencing., Patients: Twenty-eight subjects from both families were clinically assessed and subsequently molecularly analysed for the presence of RET gene mutations., Results: We have found the mutation c.1597G-->T (Gly533Cys) in two Greek families with FMTC. The mutation was detected in all seven MTC patients of both families as well as in 13 asymptomatic relatives in the heterozygote state, although one of the patients was also a homozygote due to consanguinity. The mutation shows a wide clinical heterogeneity, as there are carrier patients with age of diagnosis ranging from 23 to 88 years., Conclusions: It is likely that this mutation causes FMTC, as no other mutation was found in the RET gene, the mutation co-segregates with FMTC, and family members without the mutation are clinically unaffected. As the same point mutation was previously found in a large Brazilian family, it may be present in other populations as well. Therefore, exon 8 of RET should be screened in FMTC families with no identified common RET mutations.

BRCA1 and BRCA2 genes were screened for loss-of-function mutations in a series of 85 patients having at least one first- or second-degree relative affected by breast and/or ovarian cancer. All BRCA1 exons and BRCA2 exons 10 and 11 were screened with a combination of methods including SSCP, PTT and direct sequencing. We have found disease-associated mutations in 14 families (16.5%), eleven in BRCA1 and three in BRCA2. The known founder mutation 5382insC of BRCA1 was identified in seven unrelated families. The other mutations identified include the non-sense R1751X, the splice junction variant 5586G>A of BRCA1 and three frameshifts, 2024del5, 3034del4, and 6631del5, of BRCA2. Nine out of these 14 families had a family history of three or more breast/ovarian cancer cases. A large number of polymorphic or unclassified variants is also reported. Combined with our previously published data 5382insC was found in nine out of 20 families (45%), suggesting that this mutation may represent a common founder mutation in the Greek population.

Objective: Mutations in the gene encoding the gap junction protein connexin 26 (GJB2) have been shown as a major contributor to prelingual, sensorineural, nonsyndromic, recessive deafness. One specific mutation, 35delG, has accounted for the majority of the mutations detected in the GJB2 gene in Caucasian populations. The aim of our study was to determine the prevalence and spectrum of GJB2 mutations in prelingual deafness in the Greek population., Methods: In a collaboration with the major referral centers for childhood deafness in Greece, patients were examined by an extensive questionnaire to exclude syndromic forms and environmental causes of deafness and by allele-specific polymerase chain reaction (PCR) for the detection of the 35delG mutation. Patients heterozygous for the 35delG mutation were further analyzed by direct genomic sequencing of the coding region of the GJB2 gene., Results: The 35delG mutation was found in 42.2% of the chromosomes in 45 familial cases of prelingual, nonsyndromic deafness (18 homozygotes and 2 heterozygotes) and in 30.6% of the chromosomes in 165 sporadic cases (45 homozygotes and 11 heterozygotes). Direct genomic sequencing in heterozygous patients revealed the L90P (2 alleles), W24X (2 alleles), R184P (2 alleles), and 291insA (1 allele) mutations., Conclusion: Mutations in the GJB2 gene are responsible for about one third of prelingual, sensorineural, nonsyndromic deafness in the Greek population, and allele-specific PCR is an easy screening method for the common 35delG mutation., (Copyright 2002 Elsevier Science Ireland Ltd.)

Mutations in the gene encoding the gap-junction protein connexin 26 (GJB2) on chromosome 13q11 have been shown as a major contributor to prelingual, sensorineural, nonsyndromic deafness. One specific mutation, 35delG, has accounted for the majority of the mutations detected in the GJB2 gene in Caucasian populations and is one of the most frequent disease mutations identified so far with highest carrier frequency of 3,5% in the Greek population. In a collaboration with the major referral centers for childhood deafness in Greece, patients were examined by an extensive questionnaire to exclude syndromic forms and environmental causes of deafness and by allele-specific PCR for the detection of the 35delG mutation. The 35delG mutation was found in 32.1% of the alleles in 173 unrelated cases of prelingual deafness: 50 homozygotes and 11 heterozygotes. Individuals heterozygous for the 35delG mutation were further analyzed by direct genomic sequencing of the coding region of the GJB2 gene, which revealed R184P and 486insT mutations in single alleles. We conclude that the 35delG GJB2 mutation is responsible for one third of prelingual, sensorineural deafness in Greece, which is higher than the usually quoted 20% for Caucasian populations., (Copyright 2002 S. Karger AG, Basel)

Family history is a well-recognized risk factor for the development of breast cancer. The isolation of BRCA1 and BRCA2 genes, the two major predisposing genes in familial and to early onset breast and ovarian cancer, has resulted to the identification of a large number of families with mutations in these two genes. Despite the large number of distinct mutations detected in both genes, several mutations have been found to recur in unrelated families of diverse geographical origin. We have analyzed 27 Greek patients with familial breast cancer the majority of those having one first and one second degree relatives affected and 28 patients with sporadic breast cancer for BRCA2 germline mutations. The techniques used were single-strand conformation polymorphism analysis (SSCP) followed by sequencing. Furthermore, the clinical presentation and prognosis of BRCA2 associated breast cancer cases was compared to 20 adequately matched for age and date of diagnosis (within one year) sporadic breast cancer patients. We identified three novel BRCA2 mutations (3058delA, 6024delTA, and 4147delG) in the ovarian cancer cluster region (OCCR) and one already known (2024del5) germline BRCA2 gene mutation in five different breast cancer families. The 4147delG mutation was detected in two unrelated patients. BRCA2 germline mutations were correlated with early-onset breast cancer RR=4.77 (95% CI: 0.666-34.463). Although patients with BRCA2 germline mutations did not have a distinct histological phenotype they had an improved overall survival (100% vs 65%). Our findings suggest that there is a cluster of novel mutations in exons 10 and 11 in Greek patients with familial breast cancer. These mutations appear to have a milder clinical phenotype when compared to the rest of the study group., (Copyright 2001 Wiley-Liss, Inc.)

Germline mutations in BRCA1 gene account for varying proportions of breast/ovarian cancer families, and demonstrate considerable variation in mutational spectra coincident with ethnic and geographical diversity. We have screened for mutations the entire coding sequence of BRCA1 in 30 breast/ovarian cancer women with family history of two or more cases of breast cancer under age 50 and/or ovarian cancer at any age. Genomic DNA from patient was initially analyzed for truncating mutations in exon 11 with PTT followed by DNA sequencing. In the cases where no frameshift mutation was observed in exon 11, all other exons were screened with direct sequencing. Two novel (3099delT, 3277insG) and three already described (3741insA, 1623del5-TTAAA, 5382insC-twice) truncating mutations were identified. In addition, 6 point mutations (L771L, P871L, E1038G, K1183R, S1436S, S1613G) which are already classified as polymorphisms were identified. Three unclassified intronic variants (IVS16-68 G>A, IVS16-92 G>A, IVS18+65G>A) were also detected. These results show that BRCA1 deleterious mutations are present in a fraction (20%) of Greek breast/ovarian cancer families similar to other European countries. Mutations were detected in high- (>/=3 members) as well as in moderate-risk (2 members) families. This is the first report of BRCA1 mutation analysis in Greece., (Copyright 2000 Wiley-Liss, Inc.)