Pleomorphic/solid lobular carcinoma of male breast with PALB2 germline mutation: case report and literature review.

Male breast cancer (MBC) accounts for approximately 1% of all breast cancers and among these infiltrating lobular carcinomas (ILC) represents only 1-2% of all MBC cases. Pleomorphic invasive lobular carcinoma (PILC) is an aggressive variant of ILC with only eight cases reported until now in males. Up to 10% of MBC cases have a germline pathogenic variant in a predisposing gene such as BRCA1 and BRCA2 genes. Mutations in PALB2 (partner and localizer of BRCA2) have been reported in men with breast cancer, with a frequency that ranges from 0.8 to 6.4%, but it has never been reported in male ILC. Here, we report a rare and interesting case of an invasive pleomorphic/solid lobular carcinoma, which carries a pathogenic variant in PALB2 gene, and a family history of breast cancer without other well defined risk factors for developing this type of neoplasia. In addition, we review the current literature.

Genetic Testing and Clinical Management Practices for Variants in Non-BRCA1/2 Breast (and Breast/Ovarian) Cancer Susceptibility Genes: An International Survey by the Evidence-Based Network for the Interpretation of Germline Mutant Alleles (ENIGMA) Clinical Working Group.

PURPOSE: To describe a snapshot of international genetic testing practices, specifically regarding the use of multigene panels, for hereditary breast/ovarian cancers. We conducted a survey through the Evidence-Based Network for the Interpretation of Germline Mutant Alleles (ENIGMA) consortium, covering questions about 16 non-BRCA1/2 genes. METHODS: Data were collected via in-person and paper/electronic surveys. ENIGMA members from around the world were invited to participate. Additional information was collected via country networks in the United Kingdom and in Italy. RESULTS: Responses from 61 cancer genetics practices across 20 countries showed that 16 genes were tested by > 50% of the centers, but only six (PALB2, TP53, PTEN, CHEK2, ATM, and BRIP1) were tested regularly. US centers tested the genes most often, whereas United Kingdom and Italian centers with no direct ENIGMA affiliation at the time of the survey were the least likely to regularly test them. Most centers tested the 16 genes through multigene panels; some centers tested TP53, PTEN, and other cancer syndrome-associated genes individually. Most centers reported (likely) pathogenic variants to patients and would test family members for such variants. Gene-specific guidelines for breast and ovarian cancer risk management were limited and differed among countries, especially with regard to starting age and type of imaging and risk-reducing surgery recommendations. CONCLUSION: Currently, a small number of genes beyond BRCA1/2 are routinely analyzed worldwide, and management guidelines are limited and largely based on expert opinion. To attain clinical implementation of multigene panel testing through evidence-based management practices, it is paramount that clinicians (and patients) participate in international initiatives that share panel testing data, interpret sequence variants, and collect prospective data to underpin risk estimates and evaluate the outcome of risk intervention strategies.

Prenatal phenotype of Williams-Beuren syndrome and of the reciprocal duplication syndrome.

KEY CLINICAL MESSAGE: Copy losses/gains of the Williams-Beuren syndrome (WBS) region cause neurodevelopmental disorders with variable expressivity. The WBS prenatal diagnosis cannot be easily performed by ultrasound because only few phenotypic features can be assessed. Three WBS and the first reciprocal duplication prenatal cases are described with a review of the literature.

Fetoplacental mosaicism: potential implications for false-positive and false-negative noninvasive prenatal screening results.

PURPOSE: Noninvasive prenatal screening for fetal aneuploidy analyzes cell-free fetal DNA circulating in the maternal plasma. Because cell-free fetal DNA is mainly of placental trophoblast origin, false-positive and false-negative findings may result from placental mosaicism. The aim of this study was to calculate the potential contribution of placental mosaicism in discordant results of noninvasive prenatal screening. METHODS: We performed a retrospective audit of 52,673 chorionic villus samples in which cytogenetic analysis of the cytotrophoblast (direct) and villus mesenchyme (culture) was performed, which was followed by confirmatory amniocentesis in chorionic villi mosaic cases. Using cases in which cytogenetic discordance between cytotrophoblast and amniotic fluid samples was identified, we calculated the potential contribution of cell line-specific mosaicism to false-positive and false-negative results of noninvasive prenatal screening. RESULTS: The false-positive rate, secondary to the presence of abnormal cell line with common trisomies in cytotrophoblast and normal amniotic fluid, ranged from 1/1,065 to 1/3,931 at 10% and 100% mosaicism, respectively; the false-negative rate was calculated from cases of true fetal mosaicism, in which a mosaic cell line was absent in cytotrophoblast and present in the fetus; this occurred in 1/107 cases. CONCLUSION: Despite exciting advances, underlying biologic mechanisms will never allow 100% sensitivity or specificity.

De novo small supernumerary marker chromosomes detected on 143,000 consecutive prenatal diagnoses: chromosomal distribution, frequencies, and characterization combining molecular cytogenetics approaches.

OBJECTIVE: The risk of clinical consequences in prenatal cases with de novo small supernumerary marker chromosomes (sSMC), often in mosaic conditions, is not easy to predict, which results in difficulties in genetic counseling. METHOD: In this study, we evaluated the frequency, the chromosomal origin, and the clinical indication of 104 de novo sSMC detected in a monocenter survey on the basis of 143,000 consecutive prenatal diagnoses, and we assessed the reliability of molecular cytogenetics technologies for sSMC characterization. RESULTS: We detected a de novo sSMC frequency of 0.072%. Its incidence in advanced maternal age group is statistically different from that found in maternal anxiety indication (<35 years old). A higher prevalence of mosaicism in chorionic villi sampling (CVS) than in amniotic fluids was also revealed related to confined placental mosaicisms. The risk of confirmation in amniotic fluids of mosaics previously revealed at CVS was 33.3%. No uniparental disomy conditions were found when imprinted chromosomes were involved in the occurrence of de novo sSMC. The majority of de novo sSMC were acrocentric derived-chromosomes, and a neocentromere formation was observed in one pregnancy. CONCLUSION: Our data support that array comparative genomic hybridization has improved sSMC characterization and demonstrate its utility in supporting genetic counseling. We propose a workflow for de novo sSMC characterization.

Recombinant chromosome 4 from a familial pericentric inversion: prenatal and adulthood wolf-hirschhorn phenotypes.

Pericentric inversion of chromosome 4 can give rise to recombinant chromosomes by duplication or deletion of 4p. We report on a familial case of Wolf-Hirschhorn Syndrome characterized by GTG-banding karyotypes, FISH, and array CGH analysis, caused by a recombinant chromosome 4 with terminal 4p16.3 deletion and terminal 4q35.2 duplication. This is an aneusomy due to a recombination which occurred during the meiosis of heterozygote carrier of cryptic pericentric inversion. We also describe the adulthood and prenatal phenotypes associated with the recombinant chromosome 4.

QF-PCR as a substitute for karyotyping of cytotrophoblast for the analysis of chorionic villi: advantages and limitations from a cytogenetic retrospective audit of 44,727 first-trimester prenatal diagnoses.

OBJECTIVES: Karyotyping on chorionic villous samples (CVS) includes the analysis of both cytotrophoblast (STC) and mesenchyme (LTC). This approach requires complex laboratory organization and trained technicians. The introduction of quantitative fluorescent polymerase chain reaction (QF-PCR) instead of conventional karyotyping in low-risk pregnancies opened its application in CVS analysis. Discordant QF-PCR and CVS cytogenetic results were reported, and strategies for CVS analysis were introduced to minimize this risk. The possibility to substitute the STC with QF-PCR was reported. The aim of this study is to evaluate benefits and limitations of the approach QF-PCR + LTC compared with the traditional method STC + LTC and to quantify the associated risks of false results. METHOD: This study is based on a retrospective cytogenetic audit of CVS results (n = 44 727) generated by the STC + LTC analytic approach. False-negative risks related to true fetal mosaicism type IV, imprinting syndromes and maternal contamination in LTC were calculated. RESULTS: Compared with STC + LTC, QF-PCR + LTC approach is associated with a cumulative false-negative risk of ~1/3100-1/4400. Costs and reporting time of STC in a high-throughput cytogenetic lab are similar to a CE-IVD marked QF-PCR analysis. CONCLUSIONS: These results should be clearly highlighted in the pre-test counseling and extensively discussed with the couple prior to testing for informed consent.

Application of a new molecular technique for the genetic evaluation of products of conception.

OBJECTIVES: Karyotyping is a well-established method of investigating the genetic content of product of conceptions (POCs). Because of the high rate of culture failure and maternal cell contamination, failed results or 46,XX findings are often obtained. Different molecular approaches that are not culture dependent have been proposed to circumvent these limits. On the basis of the robust experience previously obtained with bacterial artificial chromosomes (BACs)-on-Beads™ (BoBs™), we evaluated the same technology that we had used for the analysis of prenatal samples on POCs. METHOD: KaryoLite™ BoBs™ includes 91 beads, each of which is conjugated with a composite of multiple neighboring BACs according to the hg19 assembly. It quantifies proximal and terminal regions of each chromosome arm. The study included 376 samples. RESULTS: The failure rate was 2%, and reproducibility >99%; false-positive and false-negative rates were <1% for non-mosaic aneuploidies and imbalances effecting all three BACs in a contig. Detection rate for partial terminal imbalances was 65.5%. The mosaic detection threshold was 50%, and the success rate in macerated samples was 87.8%. The aneuploidy detection rate in samples with cell growth failure was 27.8%, and maternal cell contamination was suspected in 23.1% of 46,XX cultured cells. CONCLUSION: KaryoLite™ BoBs™ as a 'first-tier' test in combination with other approaches showed beneficial, cost-effective and clearly enhanced POC testing.

Prenatal BACs-on-Beads™: the prospective experience of five prenatal diagnosis laboratories.

OBJECTIVE: We previously reported on the validation of Prenatal BACs-on-Beads™ on retrospectively selected and prospective prenatal samples. This bead-based multiplex assay detects chromosome 13, 18, 21 and X/Y aneuploidies and the nine most frequent microdeletion syndromes. We demonstrated that Prenatal BACs-on-Beads(TM) is a new-generation, prenatal screening tool. Here, we describe the experience of five European prenatal diagnosis laboratories concerning the ongoing use of Prenatal BACs-on-Beads™ . METHODS: Some 1653 samples were analyzed. All results were confirmed by conventional karyotyping or another appropriate technique. All indications for invasive prenatal diagnosis were included. Amniotic fluid and chorionic villus samples were analyzed in equivalent proportions. RESULTS: The failure rate was 3.3% and the overall abnormality detection rate was ~1/10. Eighty-five percent of the detected abnormalities were common aneuploidies. Eleven microdeletions and duplications were identified, thus giving an overall yield for microdeletion and microduplication detection of 1/145. Compared with QF-PCR, Prenatal BACs-on-Beads™ provides an additional detection rate of ~1/250 for low-risk pregnancies. The false positive and negative rates were both <1%. CONCLUSION: When associated with conventional karyotyping, the Prenatal BACs-on-Beads™ assay combines a short turnaround time (typical of rapid aneuploidy detection tests) with valuable detection of the most frequent microdeletion syndromes that cannot be detected in cytogenetic analyses.

SHOX duplications found in some cases with type I Mayer-Rokitansky-Kuster-Hauser syndrome.

PURPOSE: The Mayer-Rokitansky-Küster-Hauser syndrome is defined as congenital aplasia of müllerian ducts derived structures in females with a normal female chromosomal and gonadal sex. Most cases with Mayer-Rokitansky-Küster-Hauser syndrome are sporadic, although familial cases have been reported. The genetic basis of Mayer-Rokitansky-Küster-Hauser syndrome is largely unknown and seems heterogeneous, and a small number of cases were found to have mutations in the WNT4 gene. The aim of this study was to identify possible recurrent submicroscopic imbalances in a cohort of familial and sporadic cases with Mayer-Rokitansky-Küster-Hauser syndrome. METHODS: Multiplex ligation-dependent probe amplification was used to screen the subtelomeric sequences of all chromosomes in 30 patients with Mayer-Rokitansky-Küster-Hauser syndrome (sporadic, n = 27 and familial, n = 3). Segregation analysis and pyrosequencing were applied to validate the MLPA results in the informative family. RESULTS: Partial duplication of the Xpter pseudoautosomal region 1 containing the short stature homeobox (SHOX) gene was detected in five patients with Mayer-Rokitansky-Küster-Hauser syndrome (familial, n = 3 and sporadic, n = 2) and not in 53 healthy controls. The duplications were not overlapping, and SHOX was never entirely duplicated. Haplotyping in the informative family revealed that SHOX gene duplication was inherited from the unaffected father and was absent in two healthy sisters. CONCLUSIONS: Partial duplication of SHOX gene is found in some cases with both familial and sporadic Mayer-Rokitansky-Küster-Hauser type I syndrome.

Chromosome abnormalities investigated by non-invasive prenatal testing account for approximately 50% of fetal unbalances associated with relevant clinical phenotypes.

During the past 20 years non-invasive screening tests have been increasingly utilized in prenatal diagnosis (PD) practice. Considerable effort has been exerted by multicenter consortia to evaluate the reliability of non-invasive screening tests in detecting those women with an increased risk of having a pregnancy affected by trisomies 21, 18, and 13, monosomy X, and triploidies. To what extent this group of abnormal karyotypes accounts for the total number of phenotypically relevant fetal chromosome abnormalities has, however, never been investigated. The present report is an attempt aimed to quantify this proportion. A retrospective analysis of a homogeneous survey of 115,128 consecutive invasive prenatal tests was undertaken. All cases were classified in accordance with the indication given for the invasive testing. Cytogenetic results regarding 96,416 karyotype analyses performed because of advanced maternal age (>or=35 years) or gestational anxiety (<35 years) were considered since these are the patients who usually undergo non-invasive screening tests. We calculated the number of cases (T21, T18, T13, 45,X, and triploidy) that would have been detected by prenatal screening on the basis of the published detection rate of the combined-2 test or the quadruple test. Our findings indicate that the chromosomal abnormalities investigated by screening tests represent <50% of the fetal chromosomal abnormalities associated with an abnormal outcome ranging from intermediate-to-severe in women <35 years (45.8% and 39.6% in the first and second trimesters, respectively), and sensitivity >50% in women >or=35 years (65.1% and 61.8%, respectively). To conclude, approximately 50% of the phenotypically relevant abnormal karyotypes cannot be detected by non-invasive prenatal screening tests.

Quantitative fluorescence-polymerase chain reaction assay for the detection of the duplication of the Charcot Marie Tooth disease type 1A critical region.

Charcot Marie Tooth (CMT) syndrome is the most common hereditary peripheral neuropathy, with an incidence of about 1 in 2500. The subtype 1A (CMT1A) is caused by a tandem duplication of a 1.5-Mb region encompassing the PMP22 gene. Conventional short tandem repeat (STR) analysis can reveal this imbalance if a triallelic pattern, defining with certainty the presence of duplication, is present. In case of duplication with a biallelic pattern, it can only indicate a semiquantitative dosage of the fluorescence intensity ratio of the two fragments. In this study we developed a quantitative fluorescence-PCR using seven highly informative STRs within the CMT1A critical region that successfully disclosed or excluded the presence of the pathogenic imbalance in a cohort of 60 samples including 40 DNAs from samples with the CMT1A duplication previously characterized with two different molecular approaches, and 20 diagnostic samples from 10 members of a five-generation pedigree segregating CMT1A, 8 unrelated cases and 2 prenatal samples. The application of the quantitative fluorescence-PCR using STRs located in the critical region could be a reliable method to evaluate the presence of the PMP22 duplication for the diagnosis and classification of hereditary neuropathies in asymptomatic subjects with a family history of inherited neuropathy, in prenatal samples in cases with one affected parent, and in unrelated patients with a sporadic demyelinating neuropathy with clinical features resembling CMT (i.e., pes cavus with hammer toes) or with conduction velocities in the range of CMT1A.

Pure monosomy and pure trisomy of 13q21.2-31.1 consequent to a familial insertional translocation: exclusion of PCDH9 as the responsible gene for autosomal dominant auditory neuropathy (AUNA1).

Insertional translocations (IT) are rare structural rearrangements. Offspring of IT balanced carriers are at high risk to have either pure partial trisomy or monosomy for the inserted segment as manifested by "pure" phenotypes. We describe an IT between chromosomes 3 and 13 segregating in a three-generation pedigree. Short tandem repeat (STR) segregation analysis and array-comparative genomic hybridization were used to define the IT as a 25.1 Mb segment spanning 13q21.2-q31.1. The phenotype of pure monosomy included deafness, duodenal stenosis, developmental and growth delay, vertebral anomalies, and facial dysmorphisms; the trisomy was manifested by only minor dysmorphisms. As the AUNA1 deafness locus on 13q14-21 overlaps the IT in the PCDH9 (protocadherin-9) gene region, PCDH9 was investigated as a candidate gene for deafness in both families. Genotyping of STRs and single nucleotide polymorphisms defined the AUNA1 breakpoint as 35 kb 5' to PCDH9, with a 2.4 Mb area of overlap with the IT. DNA sequencing of coding regions in the AUNA1 family and in the retained homologue chromosome in the monosomic patient revealed no mutations. We conclude that AUNA1 deafness does not share a common etiology with deafness associated with monosomy 13q21.2-q31.3; deafness may result from monosomy of PCHD9 or another gene in the IT, as has been demonstrated in contiguous gene deletion syndromes. Precise characterization of the breakpoints of the translocated region is useful to identify which genes may be contributing to the phenotype, either through haploinsufficiency or extra dosage effects, in order to define genotype-phenotype correlations.

Prenatal detection by subtelomeric FISH and MLPA of unbalanced meiotic recombinants resulting from parental pericentric inversions.

OBJECTIVE: Pericentric inversion carriers are predisposed to produce unbalanced gametes that result in conceptuses having either a partial trisomy for one distal segment and a partial monosomy for the other or vice versa. Larger inversions result in smaller unbalanced distal segments and a higher likelihood of a viable fetus. In these cases the structure of the recombinant chromosome is similar to the original balanced inverted or normal ones despite the (unbalanced) genetic content. Such cases may not be detected prenatally by conventional cytogenetic analysis. METHODS: In all prenatal samples from the pericentric inversion carriers we applied subtelomeric FISH probes specific for the chromosome involved in order to detect parental meiotic recombinants resulting from a single cross-over event. Confirmatory MLPA was also applied in unbalanced fetuses. RESULTS: The occurrence of a duplication deficiency unbalance from pericentric inversion carriers was successfully detected in all three fetuses by FISH. MLPA assays applied in two cases confirmed these results. CONCLUSIONS: The application of commercial FISH subtelomeric probes is a reliable method that could be routinely applied for the detection of single cross-over meiotic recombinants. MLPA is a sound alternative technique.

Combined use of MLPA and nonfluorescent multiplex PCR analysis by high performance liquid chromatography for the detection of genomic rearrangements.

Large genomic rearrangements are recognized as playing a pathogenic role in an increasing number of human genetic diseases. It is important to develop efficient methods for the routine detection and confirmation of these germline defects. Multiplex ligation-dependent probe amplification (MLPA) is considered an early step for molecular diagnosis of several genetic disorders. However, artifacts might hamper the interpretation of MLPA analysis, especially when rearrangements involve a single exon. Therefore, rearrangements must be verified by two independent methods. In this study, we developed nonfluorescent multiplex-PCR coupled to high-performance liquid chromatography (NFMP-HPLC) and analyzed whether the use of this method combined with MLPA could be helpful in the detection and confirmation of gross MSH2 and MLH1 genomic rearrangements. A total of nine nonfluorescent multiplex-PCRs were developed to analyze the 16 MSH2 and 19 MLH1 exons. Reliable multiplex amplifications and nonfluorescent peak quantitation were obtained with a limited number of cycles (< or = 25) using a denaturing HPLC (DHPLC) instrument under nondenaturing conditions. The results obtained by NFMP-HPLC were highly reproducible. The combined use of MLPA and NFMP-HPLC identified and independently confirmed putative MLH1 and MSH2 deletions in eight out of 50 unrelated patients with hereditary nonpolyposis colorectal cancer (HNPCC). In five cases, the deletions affected a single exon and in three cases multiple contiguous exons. These results were in agreement with breakpoint and complementary DNA (cDNA) analyses. Considering that MLPA and NFMP-HPLC are unlikely to be affected by the same artifacts, their combined use could also provide a robust and cost-effective strategy for routine screening and confirmation of putative rearrangements in other genes, especially when a single exon is involved or a precise characterization of breakpoints is not achieved.