Tandem Triplication 11p15.5-ICR1 (H19/IGF2) Detected by Microarray and Optical Genome Mapping in a Prenatal Beckwith-Wiedemann Case.

Optical genome mapping (OGM) appears as a new tool for matching standard cytogenetic methods (karyotype and microarray) into a single assay. The chromosomal region 11p15.5 harbours two differentially methylated regions, the imprinting centre regions 1 and 2 (ICR1, ICR2). Disturbances in both regions alter human growth and are associated with two imprinting disorders, Beckwith-Wiedemann (BWS) and Silver-Russell syndromes. Herein, we present a prenatal case with a triplication in 11p15.5, including the H19/IGF2 imprinted region, detected by microarray and OGM. A 30-year-old pregnant woman of 17 weeks of gestation was referred for prenatal karyotype and microarray study because of increased nuchal translucency, short femur, megabladder, hyperechogenic bowel, and renal ectasia. Microarray, OGM, and MS-MLPA were performed, and a tandem cis-triplication in 11p15.5 and hypermethylation of the ICR1 region, compatible with BWS was detected. OGM, with its power to detect all classes of structural variants, including copy number variants, at a higher resolution than traditional cytogenetic methods can play a significant role in prenatal care and management as a next-generation cytogenomic tool. This study further supports the hypotheses that the amplification/duplication-triplication of the H19/IGF2 region could be related to BWS if it is of paternal origin.

Genomic Chaos (Multiple Copy Number Variations and Structural Reorganization) Detected in Two Prenatal Cases.

The use of new technologies in the routine diagnosis of constitutional abnormalities, such as high-resolution chromosomal microarray and next-generation sequencing, has unmasked new mechanisms for generating structural variation of the human genome. For example, complex chromosome rearrangements can originate by a chromosome catastrophe phenomenon in which numerous genomic rearrangements are apparently acquired in a single catastrophic event. This phenomenon is named chromoanagenesis (from the Greek "chromo" for chromosome and "anagenesis" for rebirth). Herein, we report 2 cases of genomic chaos detected at prenatal diagnosis. The terms "chromothripsis" and "chromoanasynthesis" and the challenge of genetic counseling are discussed.

Molecular characterization of Spanish patients with MECP2 duplication syndrome.

MECP2 duplication syndrome (MDS) is an X-linked neurodevelopmental disorder characterized by a severe to profound intellectual disability, early onset hypotonia and diverse psycho-motor and behavioural features. To date, fewer than 200 cases have been published. We report the clinical and molecular characterization of a Spanish MDS cohort that included 19 boys and 2 girls. Clinical suspicions were confirmed by array comparative genomic hybridization and multiplex ligation-dependent probe amplification (MLPA). Using, a custom in-house MLPA assay, we performed a thorough study of the minimal duplicated region, from which we concluded a complete duplication of both MECP2 and IRAK1 was necessary for a correct MDS diagnosis, as patients with partial MECP2 duplications lacked some typical clinical traits present in other MDS patients. In addition, the duplication location may be related to phenotypic severity. This observation may provide a new approach for genotype-phenotype correlations, and thus more personalized genetic counselling.

A New Case with Corpus Callosum Abnormalities, Microcephaly and Seizures Associated with a 2.3-Mb 1q43-q44 Deletion.

1q44 deletion is a rare syndrome associated with facial dysmorphism and developmental delay, in particular related with expressive speech, seizures, and hypotonia (ORPHA:238769). Until today, the distinct genetic causes for the different symptoms remain not entirely clear. We present a patient with a 2.3-Mb 1q44 deletion, including AKT3, ZBTB18, and HNRNPU, who shows microcephaly, developmental delay, abnormal corpus callosum, and seizures. The genetic findings in this case and a review of the literature spotlight a region between 243 Mb and 245 Mb on chromosome 1q related to the genesis of the typical symptoms of 1q44 deletion.

Three-Year Follow-Up of a Prenatally Ascertained Apparently Non-Mosaic sSMC(10): Delineation of a Non-Critical Region.

Small supernumerary marker chromosomes (sSMC) originating from chromosome 10 are rare and usually found in mosaic form. We present a de novo apparently non-mosaic sSMC(10) prenatally diagnosed in amniotic fluid and postnatally confirmed in peripheral blood. Characterization by array-CGH showed a pericentromeric duplication of 7.1 Mb of chromosome 10. The fetus did not show ultrasound abnormalities, and a normal female phenotype was observed during a 3-year postnatal follow-up. The absence of phenotypic abnormalities in the present case provides evidence of a non-critical pericentromeric region in 10p11.21q11.1 (hg19 35,355,570-42,448,569) associated with a duplication.

A Novel Recurrent Breakpoint Responsible for Rearrangements in the Williams-Beuren Region.

Copy number variants (CNVs) of the Williams-Beuren syndrome (WBS) 7q11.23 region are responsible for neurodevelopmental disorders with multisystem involvement and variable expressivity. We found 2 patients with a deletion and 1 patient with a duplication in this region sharing a common breakpoint located between the LIMK1 and EIF4H(WBSCR1) genes. One patient had a WBS phenotype, although testing with a commercially available FISH assay was negative for the deletion. A further test using array CGH showed an atypical WBS region deletion. The second patient showed global developmental delay, speech delay and poor motor skills with a deletion outside the WBS region. The third patient had manifestations compatible with an autism spectrum disorder showing a duplication in the WBS region. Our findings point to the existence of a previously unrecognized recurrent breakpoint responsible for rearrangements in the WBS region. Given that most commercial FISH assays include probes flanking this novel breakpoint, further testing with array CGH should be performed in patients with WBS and negative FISH results.

Intrachromosomal 3p insertion as a cause of reciprocal pure interstitial deletion and duplication in two siblings: further delineation of the emerging proximal 3p deletion syndrome.

Very few cases of constitutional interstitial deletions of the proximal short arm of chromosome 3 have been reported; however, the proximal 3p deletion is emerging as a clinically recognizable syndrome. We present an intrachromosomal insertion of 3p12.3p14.1 in a phenotypic normal man (46,XY,ins(3)(p25p12.3p14.1)) which is responsible for the unbalanced karyotype in 2 affected offspring, one with a 3p12.3p14.1 interstitial deletion and the other with a reciprocal duplication. The exceptionality of these 2 reciprocal recombinants contributes to a better definition of the proximal 3p deletion syndrome and its duplication counterpart.

Trisomy 18p caused by a supernumerary marker with a chromosome 13/21 centromere: a possible recurrent chromosome aberration.

We present a clinical and molecular cytogenetic characterization of two new patients with a complex supernumerary marker consisting of the entire short arm of chromosome 18 with a chromosome 13/21 centromere. One patient is a girl with a nonsyndromic intellectual disability and the second is a prenatally diagnosed fetus. To our knowledge, these are the fourth and fifth such cases to be described in the literature, suggesting the existence of a possible recurring constitutional structural chromosome abnormality.

Rapid prenatal diagnosis by QF-PCR: evaluation of 30,000 consecutive clinical samples and future applications.

Rapid prenatal diagnoses of major chromosome abnormalities can be performed on a large scale using highly polymorphic short tandem repeats (STRs) amplified by the quantitative fluorescent polymerase chain reaction (QF-PCR). The assay was introduced as a preliminary investigation to remove the anxiety of the parents waiting for the results by conventional cytogenetic analysis using amniotic fluid or chorionic cells. However, recent studies, on the basis of the analyses of several thousand samples, have shown that this rapid approach has a very high rate of success and could reduce the need for cytogenetic investigations. Its high efficiency, for example, allows early interruption of affected fetuses without the need of waiting for completion of fetal karyotype. The main advantages of the QF-PCR are its accuracy, speed, automation, and low cost that allows very large number of samples to be analyzed by few operators. Here, we report the results of using QF-PCR in a large series of consecutive clinical cases and discuss the possibility that, in a near future, it may even replace conventional cytogenetic analyses on selected samples.

Cytogenetic and fluorescence in situ hybridization studies in 60 patients with multiple myeloma and plasma cell leukemia.

We report cytogenetic results in a series of 60 patients affected with multiple myeloma (MM) and plasma cell leukemia (PCL) and compare the results with those previously reported. In our series, a total of 41% of MM patients and 71% of PCL patients displayed chromosome abnormalities. To evaluate the clinical value of monosomy 18, we obtained fluorescence in situ hybridization results (using centromeric probe for chromosome 18) of 22 MM patients who displayed a normal karyotype. Monosomy 18 was present in 3 of 22 patients (14%). Using conventional cytogenetics, we detected monosomy 18 in one patient affected with PCL. Two of four cases with monosomy 18 followed an aggressive course, with overall survival of 1 and 9 months. The remaining two are in follow-up and remain stable. The association of monosomy 18 with IgA subtype predominance and poor prognosis was not observed in this series of MMs and PCLs. Although these results do not confirm our previous hypothesis, further observations of this group of patients (with monosomy 18) regarding malignant transformation is warranted.

Contribution of cytogenetics and in situ hybridization to the study of monoclonal gammopathies of undetermined significance.

Monoclonal gammopathies of undetermined significance (MGUS) are characterized by the presence of a monoclonal protein in serum in quite asymptomatic patients. Ten to 33% of MGUS patients eventually will develop overt multiple myeloma, but no single laboratory test exists that can predict changes toward a malignant evolution. The aim of the present study was to apply conventional cytogenetics, the MAC (morphology, antibody, chromosome) method and fluorescence in situ hybridization (FISH) techniques in a series of 50 MGUS patients and 4 "smoldering" multiple myeloma patients to test the usefulness of their approaches as predictive methodologies. All patients studied by conventional cytogenetics presented a normal karyotype independent of the culture conditions used. The MAC method revealed that all mitotic cells showing a normal karyotype were positive for anti-MOP7 or anti-CD3 in 12 patients studied. In addition, two of them presented a numerical abnormality detected by FISH. Using a FISH technique with direct labeled centromeric probes for chromosomes 3, 7, 11, and 18 we showed a numerical abnormality in eight of 35 patients (23%) with a normal karyotype. The common occurrence of MGUS and the fact that they may evolve toward lymphoproliferative disorders displays the importance of being able to identify laboratory results that are capable of predicting the evolution of these patients. In the literature, patients who presented an IgA peak of immunoglobulin type have been associated with a higher risk of evolving to a malignant condition. Our study shows the correlation of MGUS patients who presented monosomy 18 with the presence of an immunoglobulin peak of the IgA type. Prospective follow-up is needed to evaluate the clinical value of monosomy 18 as a predictive factor for defining a high risk of malignant transformation in MGUS patients.

Rapid prenatal diagnosis of common chromosome aneuploidies by QF-PCR, results of 9 years of clinical experience.

BACKGROUND: Despite being deliberately targeted to common chromosome aneuploidies, the rapid quantitative fluorescent polymerase chain reaction (QF-PCR) tests can detect the majority of chromosome abnormalities in prenatal diagnosis. The main advantages of this assay are low cost, speed and automation allowing large-scale application. METHODS: We developed a QF-PCR test that was applied on 43 000 clinical samples reporting results in 24 h. Most common indications were biochemical risk (32%) and advanced maternal age (30%). Samples were also tested by cytogenetic analysis and the results compared. RESULTS: Aneuploidies involving chromosomes 21, 18, 13, X and Y were detected with 100% specificity. Several cases of partial trisomies and mosaicism were also identified. Overall 95% of clinically relevant abnormalities were readily detected and termination of affected pregnancies could be performed without waiting for the cytogenetic results. CONCLUSIONS: Our study supports the possibility of reducing the load of prenatal cytogenetic tests if the pregnancies are carefully monitored by non-invasive screening. In case of abnormal QF-PCR results, medical action can be taken within few hours from sampling. In cases of negative QF-PCR results, cytogenetic analyses might only be performed for fetuses with ultrasound abnormalities. In countries where large-scale cytogenetic tests are not available, QF-PCR may be used as the only prenatal diagnostic procedure.

Ectopic nucleolus organizer regions in a patient with premature ovarian failure.

OBJECTIVE: To present a case of premature ovarian failure (POF) and a complex chromosomal rearrangement involving band Xq21. DESIGN: Case report. SETTING: Department of cytogenetics, general analysis laboratory. PATIENT(S): A woman with POF and a complex translocation involving chromosomes X and 2 and a nucleolus organizer region (NOR) structure inserted in the critical region Xq21. INTERVENTION(S): Chromosomal analysis, NOR banding, hysteroscopy. MAIN OUTCOME MEASURE(S): Fluorescence in situ hybridization, comparative genome hybridization, human androgen receptor gene technique. RESULT(S): Four mechanisms may explain a causal relationship between the phenotype of the patient and her chromosome constitution. The presence of a NOR structure at the breakpoint of chromosome X suggests a complex reorganization and is of interest per se. CONCLUSION(S): Cytogenetic analysis is essential in women with unexplained POF and may provide valuable information on the chromosome location of critical regions implicated in ovarian function. However, in very complex reorganizations such as that described herein, classical cytogenetic techniques must be combined with molecular techniques to achieve a more complete characterization of the anomaly.

Two cases of tetrasomy 9p syndrome with tissue limited mosaicism.

Tetrasomy of short arm of chromosome 9 constitutes a clinically recognizable chromosomal syndrome. Isochromosome 9p shows a strong propensity to tissue-limited mosaicism. It occurs predominantly in peripheral blood cultures, often at a lower frequency or even absent in skin, amniotic fluid or chorionic villous cell cultures. Tissue-limited nature of mosaicism may render prenatal detection of this condition very difficult. Herein, we report two new cases of mosaic tetrasomy 9p. Conventional cytogenetics (CC) and FISH studies demonstrated a differential expression of the mosaicism in several tissues. We review the literature and discuss the implications of these findings in cytogenetic prenatal diagnosis.

Collection of Philadelphia-negative stem cells using recombinant human granulocyte colony-stimulating factor in chronic myeloid leukemia patients treated with alpha-interferon.

BACKGROUND AND OBJECTIVES: Autologous stem cell transplantation is a therapeutic option for chronic myeloid leukemia (CML) patients who are not candidates for allogeneic transplant. To reduce the risk of post-autografting disease recurrence, different strategies of stem cell selection have been attempted. The results of using recombinant human granulocyte colony-stimulating factor (rHuG-CSF) for harvesting hematopoietic progenitors in CML patients treated with interferon-a (IFN) are reported. DESIGN AND METHODS: Twenty-one CML patients who received IFN for a median of 21 (8-68) months were mobilized with rHuG-CSF (10 mg/kg/day). Twelve were in complete (CCR) or major (MCR) cytogenetic response. Complete success was considered a sufficient harvest (> 1 x 10(6)/kg CD34(+) cells/kg) without Philadelphia (Ph)+ metaphases in at least one apheresis; a partial success was a sufficient harvest with 1-35% Ph(+) cells. RESULTS: A total of 78 aphereses were performed. No patient had major side-effects. The median number (range) of mononuclear and CD34(+) cells obtained was, respectively, 8.6 x 10(8)/kg (0.9-22.6) and 3.3 x 10(6)/kg (0.4-26.3) per patient. A sufficient cell yield was collected in all but three patients. A complete/partial success was achieved in seven CCR/MCR patients (63%) and in three (33%) with other responses. Four patients underwent successful autografting using the stem cells obtained after rHuG-CSF mobilization. INTERPRETATION AND CONCLUSIONS: Mobilization of IFN-treated patients using rHuG-CSF is safe and provides a significant proportion of Ph-negative progenitors in CML patients in complete or major cytogenetic response.