Prenatal diagnosis of a fetus with Phelan-McDermid syndrome and 21q21 microdeletion by multiple genetic techniques / 中华医学遗传学杂志

OBJECTIVE@#To carry out prenatal diagnose for a fetus with ultrasonography abnormalities using multiple genetic techniques.@*METHODS@#Routine G-banding chromosomal analysis and single nucleotide polymorphism array (SNP-array) were applied in conjunction for the prenatal diagnosis of the fetus. The result was confirmed by fluorescence in situ hybridization (FISH).@*RESULTS@#SNP-array detected that the fetus has carried a hemizygous 5.1 Mb deletion at 22q13.31q13.33, which is associated with Phelan-McDermid syndrome, and a hemizygous 4.5 Mb deletion at 21q21.1q21.2. FISH analysis of the fetus and its parents suggested that both deletions were de novo in origin.@*CONCLUSION@#The hemizygous deletions on 21q21.1q21.2 and 22q13.31q13.33 probably underlay the abnormal phenotype of the fetus. Genetic analysis can provide crucial information for the prenatal diagnosis and genetic counseling.

Anormalidades genéticas e de metilação de DNA em uma coorte de leucemia linfoblástica aguda pediátrica com alterações no cromossomo 21 / Genetic and DNA methylation abnormalities in a cohort of acute lymphoblasticleukemia with chromosome 21 alterations

A leucemia linfoblástica aguda de células precursoras B (LLA-CPB) é uma neoplasia heterogênea. Aproximadamente 60% das LLA-CPB apresentam alterações envolvendo o cromossomo 21, incluindo hiperdiploidia, fusão gênica ETV6‐UNX1 e amplificação intracromossomal do cromossomo 21 (iAMP21). Mecanismos epigenéticos contribuem para a leucemogênese e a metilação do DNA, por sua vez, pode ser modulada por polimorfismos na via do folato. Portanto, este estudo tem como objetivo caracterizar o perfil genético e de metilação de DNA em LLA-CPB com alterações no cromossomo 21. Este estudo partiu de uma série de 1006 casos de LLA-CPB diagnosticados de 2002-2016 e foi desenhado em 3fases: 1) Identificação dos casos com alterações em número de cópias (CNA) no cromossomo 21 usando multiplex ligation probe amplification (MLPA) e FISH (RUNX1 e sondas para os cromossomos 4, 8, 10, 14, 17, 18, X e Y); 2) Caracterização do perfil de metilação e CNA por meio da técnica de microarranjo. Para tanto, o DNA foi modificado com EZ DNA Methylation™ Kit e o perfil de metilação analisado pelo Infinium Human Methylation 450 BeadChip Kit; e 3) Análises comparativas de metilação de DNA gene-específica, metilação em LINE-1(pirosequenciamento) e genotipagem para o polimorfismo MTHFR rs1801133 (PCR-RFLP) entre os diferentes subtipos moleculares de LLA-CPB, controles e amostras em remissão. Encontramos evidências de ganhos em CNA no cromossomo 21 em 83/374 (22%) das amostras (MLPA)...

B-cell precursor acute lymphoblastic leukemia (BCP-ALL) is a heterogeneous disease. Approximately 60% of BCP-ALL present alterations involving chromosome 21 (chr 21), including high hyperdiploid, ETV6‐RUNX1 fusion and intrachromosomal amplification of thechromosome 21 (iAMP21). Contributing with this process, epigenetic mechanisms could regulate the transcription and induce leukemogenesis. Polymorphisms in genes involved in folate metabolism could influence this aberrant methylation. This study aimed to characterize the genetic and DNA methylation profile of BCP-ALL with chr 21 aberrations, as well as to identify the DNA methylation signatures of different BCP-ALL molecular subgroups. This study enrolled 1006 BCP-ALL diagnosed between 2002-2016 and was performed in tree steps: 1) Identification of copy number alterations (CNA) regarding the Chr 21 by multiplex ligation probe amplification (MLPA) and FISH (“LPH012 TEL/AML1 translocation, dual fusion probe and centromere probes to chr 4, 8, 10, 14, 17, 18, X and Y); 2) DNA methylation and CNAcharacterization by DNA methylation array. DNA from BCP-ALL cases, controls and remission samples was modified with EZ DNA Methylation™ Kit and analyzed by the InfiniumHumanMethylation450 BeadChip Kit; 3) Comparative gene methylation, LINE-1 methylation (pyrosequencing) and MTHFR rs1801133 genotype (PCR-RFLP) analysis between the different BCP-ALL subgroups. We found evidence of gains in chr 21 in 83/374 (22%) of the samples analyzed by MLPA. Among the BCP-ALL with chr 21 gains, 11/83 (13%) had ≥5 RUNX1 signals and 53/83 (64%) were classified as hyperdiploid...

Trastornos neurológicos graves y malformaciones en una niña con monosomía del cromosoma 21 / Severe neurological disorders and malformations in a girl with mo- nosomía of the chromosome 21

Se presenta el caso de una niña de 7 años de edad, que fue remitida a la Consulta de Asesoramiento Genético, por presentar malformaciones congénitas severas y rasgos dismórficos, asociado a un retardo del neurodesarrollo. Al nacer se diagnosticó una comunicación interauricular, lo cual fue corregido mediante operación cardiaca. Se le realizó estudio por técnicas de citogenética convencional obteniéndose como resultado una monosomía del cromosoma 21. El estudio de citogenética molecular por técnica FISH detectó una inserción de la zona crítica del 21 en la región subtelomérica del 6p.

The case of a 7-year-old girl is showed. She was referral to the Genetic Advice Session, for presenting severe congenital malformations and dysmorphisms, associated with a neurological delay. A canal inter auricle was diagnosed at birth, which was corrected through heart surgery. The conventional cytogenetic analyzed showed a 21 chromosome monosomy. The study of molecular cytogenetic detected an insertion of the critical region of 21 in the subteloméric 6p region.

Utilidad diagnóstica del examen molecular de los genes PPA, PSEN-1 y PSEN-2 en Enfermedad de Alzheimer de inicio temprano / Diagnostic utility of the molecular examination of the genes PPA, PSEN-1 and PSEN-2 in early onset Alzheimer's disease

INTRODUCCIÓN: la enfermedad de Alzheimer (EA) es una enfermedad neurodegenerativa de evolución progresiva que representa el tipo más común de demencia. El riesgo de presentar enfermedad de Alzheimer familiar (EAF) puede aumentar 2 a 4 veces entre los individuos que tienen un familiar de primer grado con la enfermedad, para la cual se han identificado mutaciones en tres genes, definidas como causales (PSEN-1, PSEN-2 y APP). OBJETIVO: evaluar la utilidad del estudio molecular de los genes PSEN-1, PPA, PSEN-2 (cromosomas 14, 21 y 1) en el diagnóstico de enfermedad de Alzheimer de inicio temprano (EAIT). METODOLOGÍA: se realizó una búsqueda de evidencia en las bases de datos: MEDLINE, EMBASE, la Librería Cochrane y LILACS. Dos evaluadores de manera independiente, tamizaron las referencias obtenidas, resolviendo las discrepancias por consenso. Se identificaron únicamente estudios descriptivos, a partir de los cuales se basan los resultados del presente informe. RESULTADOS: se identificaron 5 estudios descriptivos. Los estudios confirman la identificación de los 3 genes determinantes en la aparición de la enfermedad de EAIT; las mutaciones más frecuentemente identificadas son las pertenecientes al gen PSEN-1. CONCLUSIONES: el estudio molecular de los genes PSEN-1, PSEN-2 y PPA en pacientes con demencia de inicio temprano (< de 65 años) e historia familiar de demencia, se considera el patrón de oro para el diagnóstico de EAIT de transmisión autosómico dominante.(AU)

Rapid detection of chromosome X, Y, 13, 18, and 21 aneuploidies by primed in situ labeling/synthesis technique.

AIMS AND OBJECTIVE: Primed in situ labeling/synthesis (PRINS) technique is an alternative to fluorescent in situ hybridization for chromosome analysis. This study was designed to evaluate the application of PRINS for rapid diagnosis of common chromosomal aneuploidy. MATERIALS AND METHODS: We have carried out PRINS using centromere specific oligonucleotide primers for chromosome X, Y, 13, 18 and 21 on lymphocyte metaphase and interphase cells spread. Specific primer was annealed in situ, followed by elongation of primer by Taq DNA polymerase in presence of labeled nucleotides. Finally, reaction was stopped and visualized directly under fluorescent microscope. RESULTS: Discrete centromere specific signals were observed with each primer. CONCLUSION: PRINS seems to be a rapid and reliable method to detect common chromosome aneuploidy in peripheral blood lymphocyte metaphase and interphase cells.

Discerning non-disjunction in down syndrome patients by means of GluK1-(AGAT) n and D21S2055-(GATA) n microsatellites on chromosome 21.

Introduction: Down syndrome (DS), the leading genetic cause of mental retardation, stems from non-disjunction of chromosome 21. Aim: Our aim was to discern non-disjunction in DS patients by genotyping GluK1-(AGAT) n and D21S2055-(GATA) n microsatellites on chromosome 21 using a family-based study design. Materials and Methods: We have used a PCR and automated DNA sequencing followed by appropriate statistical analysis of genotype data for the present study Results and Discussion: We show that a high power of discrimination and a low probability of matching indicate that both markers may be used to distinguish between two unrelated individuals. That the D21S2055-(GATA) n allele distribution is evenly balanced, is indicated by a high power of exclusion [PE=0.280]. The estimated values of observed heterozygosity and polymorphism information content reveal that relative to GluK1-(AGAT) n [H obs =0.286], the D21S2055- (GATA) n [H obs =0.791] marker, is more informative. Though allele frequencies for both polymorphisms do not conform to Hardy-Weinberg equilibrium proportions, we were able to discern the parental origin of non-disjunction and also garnered evidence for triallelic (1:1:1) inheritance. The estimated proportion of meiosis-I to meiosis-II errors is 2:1 in maternal and 4:1 in paternal cases for GluK1-(AGAT) n , whereas for D21S2055-(GATA) n , the ratio is 2:1 in both maternal and paternal cases. Results underscore a need to systematically evaluate additional chromosome 21-specific markers in the context of non-disjunction DS.

[Quantitative real-time PCR technique for rapid diagnosis of trisomy 21]

Prenatal diagnosis and prevention of live-born children with Down syndrome is a principle priority of Iran's ministry of health. The aim of this study was the rapid diagnosis of Down syndrome by quantitative real-time PCR technique as a new method for prenatal diagnosis. In this experimental study, two milliliters of peripheral blood was obtained from each patient and normal control. Then genomic DNA was extracted using salting out method. DYRK1A2 gene as target gene and PMP22 gene as reference gene were analyzed by quantitative real-time PCR technique. DYRK1A2/PMP22 gene ratio was 1.68 +/- 0.13 and 1.00 +/- 0.09 in Down syndrome and normal samples, respectively [p<0.001], demonstrating 3 copies of target [DYRK1A2] gene in trisomy 21 syndrome and 2 copies in normal individuals. DYRK1A2/PMP22 gene ratio is significantly higher in patients with Down syndrome compared with normal individuals. So, quantitative real-time PCR technique can be used as a sensitive, accurate and reliable technique for rapid diagnosis of trisomy 21 syndrome

Preimplantation genetic screening (PGS) in infertile female age > or = 35 years by fluorescence in situ hybridization of chromosome 13, 18, 21, X and Y.

INTRODUCTION: It is common in infertile couples that the female partner age > or = 35 years, that some of them require assisted reproductive technology (ART) for their treatment, it is also well known that in this female age group increases the chance of chromosome aneuploidy in offsprings. It is known that the antenatal diagnosis may have the ethical dilemma and psychological impact. Therefore, the preimplantation genetic screening (PGS) may have a role in this ART group. OBJECTIVE: The present study had the objective to compare the incidence of normal, abnormal embryos and also aneuploidy of each chromosome, i.e. 13, 18, 21, X and Y between 2 subgroups of age i.e. the age 35-39 years and 32-39 years vs. the age > or = 40 years in both female and male partners respectively. MATERIALS AND METHOD: This prospective study was performed in 20 infertile couples attending the Fertility Clinic at Thammasat University Hospital during the years 2006-2007 of which the female partner aged > or = 35 years had to use the ART. The PGS was performed by FISH technique with 5 probes to detect the 13, 18, 21, X and Y chromosomes. The comparative analysis was made between 2 subgroups of both female and male partner aged, as mentioned above in the incidence of normal, abnormal embryos and aneuploidy of each chromosome by Chi-square test and Fisher's exact test with statistical significance if p < 0.05. RESULTS: The abnormal embryos in the female partner age > or = 40 years were higher than those of the age 35-39 years (72.4% vs. 52.5%, p = 0.07) but with no statistical significance. No different results were obtained in the comparable male partner age groups (56.8% vs. 61.4%, p = 0.66). The normal female and male embryos in the female partner age 40 years were lower than those of the age 35-39 years (10.4% vs. 25.4%, p = 0.08 and 17.2% vs. 22.1%, p = 0.60 respectively) but with no statistical significance. The normal female and male embryos in the male partner age > or = 40 years and the age 32-39 years were also compared with no significant differences (20.5% vs. 20.5%, p = 1.00 and 22.7% vs. 18.2%, p = 0.60, respectively). The percentage of embryos with aneuploidy of chromosome 18 in the female partner age > or = 40 years was significantly higher than that of the age 35-39 years (72.0% vs. 45.0%, p = 0.003). The pregnancy rate in the presented PGS study was 12.5% but unfortunately was associated with a high abortion rate of 100%. CONCLUSION: It was found in the present study that the incidence of abnormal embryos trend to increase in the female partner aged > or = 40 years compared to the aged 35-39 years although with no statistical significance. However, the incidence of embryos with aneuploidy of chromosome 18 was higher in females aged > or = 40 years with statistical significance, whereas the male partner age had no impact on the abnormality or normality of the embryo. The abortion rate was very high (100%) probably may be due to inadequate choice of probes, inappropriate fixation technology and small sample size. However, the results obtained in this study indicate that the PGS should be considerably performed with strong indication only.

AML1-ETO positive AML: first report from India.

Translocation (8;21) is associated with few typical morphological features and favorable prognosis. All patients of AML and MDS with increased blasts (N = 35) according to FAB criteria, presenting (between Jan 2004 to June 2005) to the Department of Hematology, AIIMS were studied. RT-PCR was done for the AML1-ETO fusion transcript in all cases. Overall incidence of AML1-ETO was 28.57% and no correlation was found between AML1-ETO positivity and clinical or hematological parameters except for a direct correlation with absolute blast count (ABC) (a lower ABC in the AML1-ETO positive cases). Interestingly, 1/3 MDS cases were positive for the same fusion transcript and thus, it appears worthwhile to look for AML1-ETO in all cases of MDS with increased blasts. Objective morphological evaluation using a scoring system based on morphological features was not helpful in predicting positivity for AML1-ETO. The effect of this translocation on long-term survival could not be determined by the present study.

Complex glycerol kinase deficiency: an X-linked disorder associated with adrenal hypoplasia congenita.

Complex glycerol kinase deficiency (GKD) results from the contiguous deletion on Xp21 of all or part of the gene for glycerol kinase together with that for adrenal hypoplasia congenita (AHC) and /or Duchenne muscular dystrophy (DMD). The authors present the case of a newborn whose initial issues were refractory hypoglycaemia along with hyponatremia and hyperkalemia. He also had low serum cortisol levels and raised urinary excretion of glycerol and required steroid supplementation. His creatinine phosphokinase (CPK) levels were normal. Molecular studies revealed a contiguous Xp21 deletion. Therapy in such cases must be prompt and includes correction of hypoglycaemia and dyselectrolytemia, a low fat diet and steroid replacement.

Rapid Prenatal Diagnosis of Trisomy 21 by Real-time Quantitative Polymerase Chain Reaction with Amplification of Small Tandem Repeats and S100B in Chromosome 21

Trisomy 21 (Down syndrome) is the most common congenital anomaly, and it occurs in one out of 700-1000 births. Current techniques such as amniocentesis and chorionic villi sampling (CVS) require lengthy laboratory culture procedures and high costs. This study was undertaken to establish a rapid prenatal diagnosis of trisomy 21 using real-time quantitative polymerase chain reaction (PCR) of fetal DNA from amniotic fluid. Real-time quantitative PCR was performed with DNA templates obtained from 14 normal blood samples, 10 normal amniotic fluid samples, 14 Down syndrome blood samples, and 7 Down syndrome amniotic fluid samples. Primers for D21S167 and S100B of chromosome 21 were used. Primers that direct the amplification of the 165-bp fragment of the insulin-like growth factor (IGF) -1 gene on chromosome 12 using a PCR primer were included to generate an internal standard for quantitation. The relative levels of D21S167 and S100B were 2.6 and 2.4 times higher in the blood of Down syndrome patients than those in the control group. The differences between these two groups were statistically significant (p-values were 0.0012 and 0.0016, respectively). The relative levels of D21S167 and S100B were 2.1 and 2.7 times higher in the amniotic fluid of Down syndrome fetuses than those in the control group. The difference between these two groups was statistically significant (p-values were 0.0379 and 0.0379, respectively). Prenatal diagnosis of trisomy 21 by real-time quantitative PCR using STR (small tandem repeats) amplification of D21S167 and S100B is a useful, accurate and rapid diagnostic method. Furthermore, it may also be useful for prenatal diagnosis with fetal DNA from maternal blood, and for preimplantation genetic diagnosis and prenatal counseling.

Prenatal diagnosis of partial trisomy 21 associated with maternal balanced translocation 46xx der 21 t(21q;22q) with pericentric inversion of chromosome 9.

This communication reports prenatal diagnosis of partial trisomy 21 resulting from balanced translocation (21q;22q) in a 36-year-old gravida 7, para 1 woman. The lady had only one living child and there was history of recurrent spontaneous first trimester abortions. Triple test was abnormal in the present conception. In addition, the woman had pericentric inversion of chromosome 9, a finding scarcely reported previously with carrier status in Indian literature. A few cytogeneticists consider this as a normal variant. However, many reports in the recent literature link pericentric inversion of chromosome 9 with infertility, recurrent abortions and a number of other abnormal conditions. A review of the relevant literature pertinent to the case is provided.

Translocation Down syndrome.

Cytogenetic investigations carried on 1021 cases of Down syndrome revealed translocation in 46 cases. The most frequent was of t(14;21) and t(21;21) types. Most of the translocation DS cases (n = 31) were born to younger mother's (< 25 years), when compared to pure trisomy 21 DS cases. Parental karyotypes, family history and parental ages has helped us greatly in offering genetic counseling, prenatal diagnosis and estimating the risk for the next conception.

La genética de la enfermedad de Alzheimer / The genetics of Alzheimer's disease

Se presenta una revisión de la genética de la Enfermedad de Alzheimer (EA). Cerca de un tercio de los casos, especialmente los de iniciación precoz, presentan familiaridad consistente, en general, con herencia autosómica dominante. La asociación de la EA con el síndrome de Down, llevó a la investigación del cromosoma 21 en la etiología de la EA. Estudios moleculares realizados a partir de 1987, evidenciaron por lo menos 3 genes, en los cromosomas 21, 19 y 14, vinculados a la enfermedad en diferentes familias indicando heterogeneidad genética de la enfermedad. La proteína beta amiloide se deposita intensamente en el cerebro de los afectados y su sustancia presursora fue mapeada en el cromosoma 21q21'q22. Estudios citogenéticos mostraron como sitio frágil el locus del gen de una enzima antioxidante, la superóxido dismutasa mitocondrial. Las perspectivas de estos estudios y el consejo genético de la EA también son discutidos