In order to contribute to the knowledge of type and frequency of chromosome abnormalities in early pregnancy losses, we analyzed the cytogenetic results from a large series of first trimester miscarriages, using a diagnostic approach with a high success rate and no maternal contamination. A total of 1,119 consecutive chorionic villi samples were obtained before evacuation, and karyotypes were prepared after short-term culture (STC). In 603 samples, a long-term culture (LTC) was also performed. The overall and individual frequencies of the different types of chromosome abnormalities were established, including placental mosaicisms, and their relationship with maternal age and gestational weeks was assessed. An abnormal karyotype was detected in 70.3% of the samples. Single autosomal trisomy was the most frequent abnormality (64.6% of the abnormal cases), followed by triploidy (13.1%) and monosomy X (10.4%). Chromosome rearrangements were found in 5.2%, combined abnormalities in 8.9%, and placental mosaicism in 3.5% of the cases with STC and LTC performed. Individual trisomies behaved differently with respect to maternal age and intrauterine survival. Due to the combination of STC and LTC, our study offers reliable information on the incidence and type of chromosome abnormalities and placental mosaicism in miscarriages and contributes to define the cytogenetic implication in their etiology.

The patient was referred for prenatal diagnosis due to the sonographic finding of a polymalformed male fetus, and an amniocentesis was performed before termination of pregnancy. The pathological study of the placenta did not show morphological alterations. In her next pregnancy, sonographic examination disclosed a missed abortion with a visible embryo, and a chorionic villi sample was obtained for cytogenetic analysis before evacuation. Macroscopic examination of the villi sample did not reveal molar vesicular appearance. QF-PCR and cytogenetic analyses were performed on amniotic fluid (first pregnancy) and chorionic villi samples (second pregnancy). A 69,XXY and 92,XXXY karyotype was found, respectively. QF-PCR results disclosed 2 maternal and 1 paternal alleles in the first pregnancy (digynic triploidy), and double maternal and double paternal contribution to the tetraploid pregnancy. Among the few reported cases of 92,XXXY tetraploidy, those associated with partial moles show a PPPM genotype (3 paternal and 1 maternal alleles), and the only case with a PPMM genotype was found in a spontaneously aborted fetus similar to our case. We are not aware of other cases with combination of a digynic triploid pregnancy and a tetraploid pregnancy with a PPMM contribution. Our case adds evidence to the influence of the balance between paternal and maternal genomic doses on the phenotype.

Objective: To analyze karyotype of Turner's syndrome (TS) patients in two tissues of different lineage, and to correlate them with phenotype.Study design: An observational study was designed at the Gynaecological Endocrinology Unit of Hospital Clinic in Barcelona. Patients diagnosed with TS by blood karyotype were included, between 20 and 50 years of age. A new 50-cell count blood karyotype and a urethral cell karyotype from urine samples were performed. Data on some TS-related comorbidities were collected.Results: Twenty-seven TS patients were included. Urine cultures of 12 patients were contaminated by microorganisms. With 50-cell count blood karyotype, three cryptic mosaicisms were found. Six patients with mosaicism in blood karyotype showed pure monosomy in urine karyotype. Correlations exist between blood karyotype and phenotype where spontaneous menarche, height, dysmorphology, congenital malformations and hypothyroidism are concerned, whereas they did not appear in urine analysis.Conclusions: Karyotyping T-lymphocytes in blood samples is the gold standard technique. 50-cell count may be considered if TS or ovarian failure is suspected, in order to detect cryptic mosaicisms. Urethral cell culture from urine samples presents technical difficulties and some limitations, due to the easier lost of abnormal X-chromosome. A partial correlation between blood karyotype and phenotype exists.

ABSTRACTObjectivesTo assess the frequency of karyotype abnormalities and chromosome 22q11.2 deletion syndrome among fetuses with abnormal cardiac ultrasound findings, and to evaluate the clinical value of chromosomal microarray‐based analysis (CMA) in the study of such pregnancies.MethodsFirst, we carried out retrospective analysis of karyotype abnormalities and 22q11.2 deletion syndrome cases diagnosed between January 2009 and December 2011 in our center among fetuses with abnormal cardiac ultrasound findings (n = 276). Second, CMA was performed in 51 of the fetuses with such findings, normal karyotype and negative or no 22q11.2 deletion syndrome study, and in the only fetus with a heart defect and an apparently balanced de novo chromosomal rearrangement.ResultsOut of the 276 pregnancies with abnormal cardiac ultrasound findings, karyotyping revealed a chromosomal abnormality in 44 (15.9%). Of fetuses with normal karyotype in which 22q11.2 deletion syndrome studies were performed, 6.4% (5/78) had this microdeletion syndrome. Among fetuses with abnormal cardiac findings, normal karyotype and negative or no 22q11.2 deletion syndrome study that underwent CMA, the detection rate of pathogenic copy number variants not detected by conventional cytogenetics was 2.0% (1/51), and no variants of uncertain clinical significance were found. In the fetus with a heart defect and an apparently balanced de novo chromosomal rearrangement, CMA revealed that the rearrangement was not truly balanced.ConclusionsIn the assessment of genetic abnormalities in pregnancies with abnormal cardiac ultrasound findings, the diagnostic yield may be increased by 2% if CMA is used as a complementary tool to conventional cytogenetics. Our results suggest that CMA could be a good alternative to karyotyping in these pregnancies. Copyright © 2012 ISUOG. Published by John Wiley & Sons, Ltd.

La presencia en un paciente de un fenotipo clínico característico es la indicación usual para el estudio posnatal de posible disomía uniparental (DUP). En diagnóstico prenatal la situación es más compleja, ya que la información clínica es mucho más limitada, y los estudios de DUP se plantean únicamente en determinadas situaciones de riesgo, relacionadas con la presencia de alteraciones cromosómicas numéricas o estructurales en el conjunto feto/placenta o en los progenitores, o con la detección ecográfica de algún tipo de anomalías del desarrollo fetal o de malformaciones fetales. El objetivo del presente trabajo es presentar la experiencia de nuestro centro en diagnóstico prenatal de DUP. Desde 1998 se han realizado en nuestro centro 165 estudios prenatales de DUP de los cromosomas 6 (n = 1), 7 (n = 24), 11 (n = 4), 14 (n = 81) y 15 (n = 55) correspondientes a 154 gestaciones; en 11 de ellas se han estudiado 2 cromosomas a la vez. El estudio molecular se ha realizado mediante el análisis de segregación de marcadores microsatélites polimórficos distribuidos a lo largo del cromosoma implicado. Se han detectado 2 casos de DUP materna, uno del cromosoma 7 y otro del 15, ambos debidos a mosaicos confinados a placenta de la trisomía correspondiente. Se ha valorado la tasa de detección de DUP con respecto al tipo de indicación. Aunque la DUP es un fenómeno poco frecuente, la gravedad de sus consecuencias clínicas hace absolutamente recomendable su estudio prenatal en las situaciones de riesgo definidas por las normativas internacionales. The usual indication for postnatal uniparental disomy (UPD) testing is a characteristic clinical phenotype present in a patient. The situation in prenatal diagnosis is more complex because the clinical information is much more limited, and the UPD tests are only considered in certain risk situations related to the presence of numerical or structural chromosomal abnormalities in the foetal/placental unit and/or in the parents, or with the ultrasound detection of foetal developmental anomalies or foetal malformations. The objective of this study is to present the experience of our centre in UPD prenatal testing. A total of 165 UPD prenatal analyses were performed out in our centre since 1998, involving chromosomes 6 (n = 1), 7 (n = 24), 11 (n = 4), 14 (n = 81), and 15 (n = 55), corresponding to 154 gestations; 2 chromosomes have been studied at the same time in 11 of them. Molecular studies were carried out by segregation analysis of polymorphic microsatellite markers distributed along the involved chromosomes. Two maternal UPD cases of chromosomes 7 and 15 were detected, both of them due to confined placental mosaicism of the corresponding trisomy. The detection rate was evaluated with regard to the different indications. Although UPD is a rare phenomenon, the severity of its clinical consequences makes its prenatal study absolutely advisable in the risk situations defined in the international guidelines.

Congenital heart defects (CHD) represent the most common birth defects, so they are not a rare finding when performing routine ultrasound examinations during pregnancy. Once chromosome abnormalities have been excluded in a fetus with a CHD, chromosome 22q11.2 deletion is usually investigated by FISH, as it is the most frequent microdeletion syndrome and is generally associated with cardiac malformations. If 22q11.2 microdeletion is ruled out, the etiology of the CHD remains generally unexplained, making familial genetic counseling difficult. To evaluate the usefulness of Multiplex Ligation-dependent Probe Amplification (MLPA) kits designed for the study of 22q11.2 and other genomic regions previously associated with syndromic CHD, we performed MLPA in 55 pregnancies with fetuses presenting CHD, normal karyotype and negative FISH results for 22q11.2 microdeletion, which constitutes the largest prenatal series reported. Definitive MLPA results were obtained in 50 pregnancies, and in this setting such MLPA kits did not detect any imbalance. On the other hand, to compare FISH and MLPA techniques for the study of 22q11.2 microdeletions, we performed MLPA in 4 pregnancies known to have 22q11.2 deletions (by FISH). All four 22q11.2 microdeletions were also detected by MLPA, which corroborates that it is a reliable technique for the diagnosis and characterization of 22q11.2 deletions. Finally, we evaluated the possibility of replacing conventional FISH by MLPA for the prenatal diagnosis of CHD, comparing the diagnostic potential, results delivery times, repetition and failure rates and cost of both techniques, and concluded that FISH should still be the technique of choice for the prenatal diagnosis of fetuses with CHD.

The deletion of the long arm of chromosome 18 causes a contiguous gene deletion syndrome with a highly variable phenotype, usually related to the extent of the deleted region. The most commonly reported clinical features include: decreased growth, microcephaly, facial abnormalities, hypotonia, developmental delay, intellectual disability, congenital aural atresia with hearing impairment and limb anomalies. Here we report on a familial terminal deletion of 18q23 region transmitted from a mother to two daughters, resulting in a remarkable phenotypic variability. The deletion was first detected by conventional cytogenetic analysis in one daughter and subsequently characterized using fluorescence in situ hybridization (FISH) and array-CGH. FISH analysis using subtelomeric 18p and 18q probes confirmed the 18qter deletion in the three patients, and FISH with a whole chromosome painting probe specific for chromosome 18 excluded rearrangements with other chromosomes. Array-CGH analysis allowed us to precisely define the extent of the deletion, which spans 4.8 Mb from 71,236,891 to 76,093,303 genomic positions and includes GALR1 and MBP genes, among others. High-resolution analysis of the deletion, besides a detailed clinical assessment, has provided important data for phenotype-genotype correlation and genetic counseling in this family. Furthermore, this study adds valuable information for phenotype-genotype correlation in 18q- syndrome and might facilitate future search for candidate genes involved in each phenotypic trait.

Objective To evaluate the usefulness of subtelomeric multiplex ligation-dependent probe amplification (MLPA) in both the detection of subtelomeric rearrangements in fetuses with ultrasound abnormalities and normal karyotype, and the characterization of cytogenetically detectable rearrangements.Method We studied by subtelomeric MLPA 229 pregnancies with ultrasound findings and normal karyotype (Group 1) and five pregnancies with a cytogenetically visible but not microscopically characterizable rearrangement (Group 2). The detected imbalances were confirmed by fluorescence in situ hybridization (FISH) and parents were also studied.Results In Group 1, two clinically relevant subtelomeric imbalances (14qter deletion and 20pter deletion) and one subtelomeric imbalance of uncertain significance (X/Ypter duplication) were diagnosed, showing a detection rate of cryptic subtelomeric imbalances in these pregnancies of 1.3%. However, only 14qter deletion seems to be clearly associated with the observed prenatal findings. In Group 2, MLPA contributed to the precise description of the chromosome abnormalities.Conclusion The low detection rate of subtelomeric imbalances and the poor genotype phenotype correlations in pregnancies with ultrasound abnormalities and normal karyotype suggest that subtelomeric MLPA is not a crucial tool in the prenatal diagnosis of these cases. However, our work provides evidence that MLPA is very useful for the characterization of unbalanced karyotypes. Copyright (C) 2010 John Wiley & Sons, Ltd.

Begona Hurtado1*; Marga Nadal1*; Ester Margarit2; Aurora Sanchez2; Nerea Abasolo1; Nadia Garcia1; Pere Domenech3; Nuria Sala1 1Laboratori de Recerca Translacional, Institut Catala d’Oncologia ICO-IDIBELL, L’Hospitalet de Llobregat, Barcelona, Spain; 2Servei de Bioquimica i Genetica Molecular, Hospital Clinic and CIBERER (Centre for Biomedical Research on Rare Diseases), Barcelona, Spain; 3Unitat de Trombosi i Hemostasia, Hospital Universitari de Bellvitge, Barcelona, Spain Case Report