Cytogenetics and molecular study of ovarian cancer

Ovarian cancer represents the leading cause of death among patients with gynecological malignancies worldwide. Most of the ovarian cancer patients are diagnosed in advanced disease stage. The genetic changes underlying the initiation and progression of ovarian cancer have not yet been well defined. Identification of chromosomal aberrations is a useful strategy toward understanding tumorigenesis’ mechanisms. In this study malignant cells of the primary tumor or cancerous effusions from 23 cases with primary ovarian cancer, were investigated by conventional cytogenetic techniques (G-banding) and 28 cases with primary ovarian cancer were analyzed by molecular cytogenetics, using bicolor FISH analysis. Using G-banding technique, we focused on simple or sole chromosomal abnormalities as well as on structural aberrations with common chromosomal breakpoints, which can be involved in the initiation and evolution of neoplasmatic process. Four cases demontstrate simple or sole chromosomal abnormalities such as inv(9)(p11q13), del(10)(p12) and structural chromosomal X anomalies. Among very complex rearrangements, recurrent chromosomal anomalies with common chromosomal breakpoints of chromosomes 1, 3, 5, 6, 7, 11 and 17 were found. FISH technique was applied using a DNA p16 probe and a–satellite probe specific for chromosome 9. We focused on numerical aberrations of chromosome 9 and p16 gene alterations. In seven cases we found monosomy 9 and in ten cases polysomy 9. Moreover, eleven cases presented two cell populations, one with monosomy 9 and one with polysomy 9. As far as p16 gene alterations are concerned the gene was deleted in all cases (28/28). In twelve cases the examined cells presented gains of p16 gene equal to chromosome 9 copies. In five cases, homozygous deletion of p16 gene was found. Our findings demonstrate that numerical aberrations of chromosome 9 and p16 gene deletion are ovarian cancer common abnormalities and are observed in all histological subtypes regardless of the disease stage or grade. Study of genetic changes in ovarian cancer is of major importance, contributing in undrerstanding of tumorigenesis’ mechanisms and adding further information for the identification of genes involved in the disease initiation or evolution.Ο καρκίνος των ωοθηκών αποτελεί τον πλέον θανατηφόρο γυναικολογικό καρκίνο παγκοσμίως. Οι περισσότεροι καρκίνοι των ωοθηκών είναι ασυμπτωματικοί και το μεγαλύτερο ποσοστό διαγιγνώσκεται σε προχωρημένο στάδιο. Γενετικές αλλαγές που εμπλέκονται στην έναρξη και εξέλιξη του καρκίνου των ωοθηκών δεν έχουν καλά προσδιοριστεί. Η ταυτοποίηση χρωμοσωμικών ανωμαλιών συμβάλλει στην κατανόηση του μηχανισμού καρκινογένεσης. Στην παρούσα εργασία μελετήθηκαν με την κλασσική κυτταρογενετική μέθοδο των ταινιών (G- banding) 23 δείγματα πρωτοπαθούς όγκου ή ασκιτικού υγρού και με την μοριακή κυτταρογενετική μέθοδο (διχρωματική FISH) 28 δείγματα όγκου από γυναίκες με καρκίνο ωοθήκης. Με την μέθοδο των ταινιών (G- banding) εστιάσαμε σε απλες ή μοναδικές ανωμαλίες καθώς και σε δομικές ανωμαλίες με σταθερά σημεία θραύσης των χρωμοσωμάτων, οι οποίες μπορεί να ενοχοποιηθούν για την έναρξη ή εξέλιξη της νεοπλασματικής επεξεργασίας. Τέσσερις περιπτώσεις παρουσιάσαν απλές ή μοναδικές χρωμοσωμικές ανωμαλίες όπως inv(9)(p11q13), del(10)(p12) και δομικές ανωμαλίες του χρωμοσώματος Χ. Μεταξύ των πολύπλοκων ανακατατάξεων παρατηρήθηκαν σταθερές χρωμοσωμικές ανωμαλίες με σταθερά σημεία θραύσης χρωμοσωμάτων που αφορούσαν τα χρωμοσώματα 1, 3, 5, 6, 7, 11 και 17. Στη συνέχεια, εφαρμόσαμε την τεχνική του φθορίζοντος in situ υβριδισμού (FISH) όπου χρησιμοποιήσαμε ένα μείγμα ανιχνευτών του κεντρομεριδιακού (a-satellite) ανιχνευτού είδικου για το χρωμόσωμα 9 και ενός ειδικού ανιχνευτού για το γονίδιο p16 για να ανιχνεύσουμε αριθμητικές ανωμαλίες του χρωμοσώματος 9 και ελλείψεις του γονιδίου p16. Σε επτά περιπτώσεις παρατηρήθηκε μονοσωμία 9 και σε δέκα περιπτώσεις πολυσωμία 9. Επιπλέον, σε έντεκα περιπτώσεις παρατηρήθηκαν δύο πληθυσμοί κυττάρων ένας με μονοσωμία 9 και ένας με πολυσωμία 9. Το γονίδιο p16 είχε εξαλειφθεί σε όλες τις περιπτώσεις (28/28). Σε δώδεκα περιπτώσεις είχαμε πολλαπλά αντίγραφα (gains) του p16 αλλά ίσα με αυτά του χρωμοσώματος 9. Σε πέντε περιπτώσεις παρατηρήθηκε ομόζυγη εξάλειψη του γονιδίου p16. Τα ευρήματα μας δείχνουν ότι οι αριθμητικές ανωμαλίες του χρωμοσώματος 9 και η εξάλειψη του γονιδίου p16 είναι σταθερές ανωμαλίες στον καρκίνο της ωοθήκης και παρατηρούνται σε όλους τους ιστολογικούς υπότυπους ανεξάρτητα από το στάδιο ή το βαθμό κακοήθειας της νόσου. Η μελέτη των γενετικών αλλαγών στον καρκίνο της ωοθήκης είναι υψίστης σημασίας, συνεισφέροντας στην κατανόηση των μηχανισμών καρκινογένεσης και προσθέτοντας περισσότερες πληροφορίες για την εντόπιση γονιδίων εμπλεκομένων στην έναρξη ή εξέλιξη της νόσου

A familial case of Muenke syndrome. Diverse expressivity of the FGFR3 Pro252Arg mutation - case report and review of the literature

Muenke is a fibroblast growth factor receptor 3 (FGFR-3)-associated syndrome, which was first described in late 1990s. Muenke syndrome is an autosomal dominant disorder characterized mainly by coronal suture craniosynostosis, hearing impairment and intellectual disability. The syndrome is defined molecularly by a unique point mutation c.749C>G in exon 7 of the FGFR3 gene which results to an amino acid substitution p. Pro250Arg of the protein product. Despite the fact that the mutation rate at this nucleotide is one of the most frequently described in human genome, few Muenke familial case reports are published in current literature. We describe individuals among three generations of a Greek family who are carriers of the same mutation. Medical record and physical examination of family members present a wide spectrum of clinical manifestations. In particular, a 38-year-old woman and her father appear milder clinical findings regarding craniofacial characteristics compared to her uncle and newborn female child. This familial case illustrates the variable expressivity of Muenke syndrome in association with an identical gene mutation

Mismatch repair gene mutation spectrum in the Swedish Lynch syndrome population

Lynch syndrome caused by constitutional mismatch-repair defects is one of the most common hereditary cancer syndromes with a high risk for colorectal, endometrial, ovarian and urothelial cancer. Lynch syndrome is caused by mutations in the mismatch repair (MMR) genes i.e., MLH1, MSH2, MSH6 and PMS2. After 20 years of genetic counseling and genetic testing for Lynch syndrome, we have compiled the mutation spectrum in Sweden with the aim to provide a population-based perspective on the contribution from the different MMR genes, the various types of mutations and the influence from founder mutations. Mutation data were collected on a national basis from all laboratories involved in genetic testing. Mutation analyses were performed using mainly Sanger sequencing and multiplex ligation-dependent probe amplification. A total of 201 unique disease-predisposing MMR gene mutations were identified in 369 Lynch syndrome families. These mutations affected MLH1 in 40%, MSH2 in 36%, MSH6 in 18% and PMS2 in 6% of the families. A large variety of mutations were identified with splice site mutations being the most common mutation type in MLH1 and frameshift mutations predominating in MSH2 and MSH6. Large deletions of one or several exons accounted for 21% of the mutations in MLH1 and MSH2 and 22% in PMS2, but were rare (4%) in MSH6. In 66% of the Lynch syndrome families the variants identified were private and the effect from founder mutations was limited and predominantly related to a Finnish founder mutation that accounted for 15% of the families with mutations in MLH1. In conclusion, the Swedish Lynch syndrome mutation spectrum is diverse with private MMR gene mutations in two-thirds of the families, has a significant contribution from internationally recognized mutations and a limited effect from founder mutations.Funding Agencies|Swedish Cancer Society</p

Corticotroph Pituitary Carcinoma in a Patient With Lynch Syndrome (LS) and Pituitary Tumors in a Nationwide LS Cohort

Context: Lynch syndrome (LS) is a cancer-predisposing syndrome caused by germline mutations in genes involved in DNA mismatch repair (MMR). Patients are at high risk for several types of cancer, but pituitary tumors have not previously been reported.Case: A 51-year-old man with LS (MSH2 mutation) and a history of colon carcinoma presented with severe Cushing disease and a locally aggressive pituitary tumor. The tumor harbored a mutation consistent with the patient's germline mutation and displayed defect MMR function. Sixteen months later, the tumor had developed into a carcinoma with widespread liver metastases. The patient prompted us to perform a nationwide study in LS.Nationwide Study: A diagnosis consistent with a pituitary tumor was sought for in the Swedish National Patient Registry. In 910 patients with LS, representing all known cases in Sweden, another two clinically relevant pituitary tumors were found: an invasive nonsecreting macroadenoma and a microprolactinoma (i.e., in total three tumors vs. one expected).Conclusion: Germline mutations in MMR genes may contribute to the development and/or the clinical course of pituitary tumors. Because tumors with MMR mutations are susceptible to treatment with immune checkpoint inhibitors, we suggest to actively ask for a family history of LS in the workup of patients with aggressive pituitary tumors

Genetic anticipation in Swedish Lynch syndrome families

Among hereditary colorectal cancer predisposing syndromes, Lynch syndrome (LS) caused by mutations in DNA mismatch repair genes MLH1, MSH2, MSH6 or PMS2 is the most common. Patients with LS have an increased risk of early onset colon and endometrial cancer, but also other tumors that generally have an earlier onset compared to the general population. However, age at first primary cancer varies within families and genetic anticipation, i.e. decreasing age at onset in successive generations, has been suggested in LS. Anticipation is a well-known phenomenon in e.g neurodegenerative diseases and several reports have studied anticipation in heritable cancer. The purpose of this study is to determine whether anticipation can be shown in a large cohort of Swedish LS families referred to the regional departments of clinical genetics in Lund, Stockholm, Linkoping, Uppsala and Umea between the years 1990-2013. We analyzed a homogenous group of mutation carriers, utilizing information from both affected and non-affected family members. In total, 239 families with a mismatch repair gene mutation (96 MLH1 families, 90 MSH2 families including one family with an EPCAM-MSH2 deletion, 39 MSH6 families, 12 PMS2 families, and 2 MLH1+PMS2 families) comprising 1028 at-risk carriers were identified among the Swedish LS families, of which 1003 mutation carriers had available follow-up information and could be included in the study. Using a normal random effects model (NREM) we estimate a 2.1 year decrease in age of diagnosis per generation. An alternative analysis using a mixed-effects Cox proportional hazards model (COX-R) estimates a hazard ratio of exp(0.171), or about 1.19, for age of diagnosis between consecutive generations. LS-associated gene-specific anticipation effects are evident for MSH2 (2.6 years/generation for NREM and hazard ratio of 1.33 for COX-R) and PMS2 (7.3 years/generation and hazard ratio of 1.86). The estimated anticipation effects for MLH1 and MSH6 are smaller

A retrospective two centre study of Birt-Hogg-Dube syndrome reveals a pathogenic founder mutation in FLCN in the Swedish population

Birt-Hogg-Dube syndrome (BHDS) (MIM: 135150) is a rare autosomal dominant disorder with variable penetrance, caused by pathogenic variants in the FLCN gene. Only a few hundreds of families have so far been described in the literature. Patients with BHDS present with three distinct symptoms: fibrofolliculomas, pneumothorax due to lung cyst formation, and increased lifetime risk of kidney tumours. The aim of the current study was to estimate the incidence of BHDS in the Swedish population and further describe the clinical manifestations and their frequency. Splice variant c.779+1G&gt;T was the most common pathogenic variant, found in 57% of the families, suggesting this may be a founder mutation in the Swedish population. This was further investigated using haplotype analysis in 50 families that shared a common haplotype. Moreover, according to gnomAD the carrier frequency of the c.779+1G&gt;T variant has been estimated to be 1/3265 in the Swedish population, however our data suggest that the carrier frequency in the Swedish population may be significantly higher. These findings should raise awareness among physicians of different specialties to patients presenting with fibrofolliculomas, pneumothorax and/or kidney tumours. We also stress the importance of consensus recommendations regarding diagnosis and clinical management of this, not that uncommon, syndrome

A retrospective study of extracolonic, non-endometrial cancer in Swedish Lynch syndrome families

BackgroundLynch Syndrome is an autosomal dominant cancer syndrome caused by pathogenic germ-line variants in one of the DNA-mismatch-repair (MMR) genes MLH1, MSH2, MSH6 or PMS2. Carriers are predisposed to colorectal and endometrial cancer, but also other cancer types. The purpose of this retrospective study was to characterize the tumour spectrum of the Swedish Lynch syndrome families.MethodsData were obtained from genetically verified 235 Lynch families from five of the six health care regions in Sweden. The material was stratified for gender, primary cancer, age and mutated gene and the relative proportions of specific cancer types were compared to those in the general population.ResultsA total of 1053 family members had 1493 cancer diagnoses of which 1011 were colorectal or endometrial cancer. Individuals with pathogenic variants in MLH1 and MSH2 comprised 78% of the cohort. Among the 482 non-colorectal/non-endometrial cancer diagnoses, MSH2 carriers demonstrated a significantly increased proportion of urinary tract, gastric, small bowel, ovarian and non-melanoma skin cancer compared to the normal population. MLH1 carriers had an elevated proportion of gastrointestinal cancers (gastric, small bowel, pancreas), while MSH6 carriers had more ovarian cancer than expected. Gastric cancer was predominantly noted in older generations.ConclusionLynch syndrome confers an increased risk for multiple cancers other than colorectal and endometrial cancer. The proportions of other cancers vary between different MMR genes, with highest frequency in MSH2-carriers. Gender and age also affect the tumour spectrum, demonstrating the importance of additional environmental and constitutional parameters in determining the predisposition for different cancer types

Merged testing for colorectal cancer syndromes and re-evaluation of genetic variants improve diagnostic yield : Results from a nationwide prospective cohort

Approximately 5% of patients with colorectal cancer (CRC) have a Mendelian predisposition for the disease. Identification of the disease-causing genetic variant enables carrier testing and tailored cancer prevention within affected families. To determine the panorama and genetic variation of Mendelian CRC syndromes among referrals at the cancer genetics clinics in Sweden, 850 patients clinically selected for CRC genetic investigation were included in a prospective study that tested for all major hereditary polyposis and nonpolyposis CRC conditions. Genetically defined syndromes were diagnosed in 11% of the patients. Lynch syndrome was predominant (n = 73) followed by familial adenomatous polyposis (n = 12) and MUTYH-associated polyposis (n = 8); the latter of which two patients presented with CRC before polyposis was evident. One patient with a history of adolescent-onset CRC and polyposis had biallelic disease-causing variants diagnostic for constitutional mismatch repair deficiency syndrome. Post-study review of detected variants of unknown clinical significance (n = 129) resulted in the reclassification of variants as likely benign (n = 59) or as diagnostic for Lynch syndrome (n = 2). Our results reveal the panorama of Mendelian CRC syndromes at the cancer genetics clinics in Sweden and show that unified testing for polyposis and nonpolyposis CRC conditions as well as regular reexamination of sequence data improve the diagnostic yield.Funding Agencies|health-care regions in Sweden</p