Genetic analysis of a case with mosaicism of a small supernumerary marker chromosome derived from idic(15) / 中华医学遗传学杂志

OBJECTIVE@#To determine the origin of a mosaicism small supernumerary marker chromosome (sSMC) by cytogenetic and molecular analysis.@*METHODS@#Karyotype analysis, fluorescence in situ hybridization (FISH) and SNP-array were carried out.@*RESULTS@#The karyotype of the patient was mos47,XX,+mar[45]/48,XX,+2mar[3]/46,XX[52]; the SNP-array result was arr[hg19]15q11.1q11.2 (20 161 372-24 314 675)×3, and the repeat fragment was about 4.15 Mb. FISH showed that approximately 50% of the cells have contained a sSMC with double D15Z1 probe site segments derived from abnormal idic(15). This sSMC did not contain SNRPN and PML probe fragments of Prader-Willi syndrome/Angelman syndrome.@*CONCLUSION@#When the patient's karyotype and phenotype are inconsistent, cytogenetic and molecular biology technologies should be combined to clarify the karyotype and gene location, so as to provide more accurate genetic consultation for the follow-up treatments.

Clinical and genetic study of a child with 15q11.2 microduplication / 中华医学遗传学杂志

OBJECTIVE@#To explore the genetic basis of a child with developmental delay and intellectual disability.@*METHODS@#Peripheral blood samples of the child and his parents were collected for routine G-band karyotyping analysis and single nucleotide polymorphism array (SNP array) assay. Amniotic fluid sample was collected during the next pregnancy for prenatal diagnosis.@*RESULTS@#No karyotypic abnormality was found in the child and his parents. SNP array showed that the child has carried a 855.3 kb microduplication in 15q11.2. His mother carried the same duplication but had no phenotypic anomaly. No microdeletion/microduplication was found in his father. Upon prenatal diagnosis, no abnormalities was found with the chromosomal karyotype and SNP array result of the fetus.@*CONCLUSION@#15q11.2 microduplication may result in developmental delay and intellectual disability, for which CYFIP1 may be a candidate gene. However, the duplication may increase the risk but with a low penetrance. This should attract attention during clinical consultation.

Genetic diagnosis and non-invasive prenatal testing of a fetus with Prader-Willi/Angelman syndrome / 中华医学遗传学杂志

OBJECTIVE@#To explore the genetic basis for a fetus featuring growth restriction and validate the effectiveness of a novel noninvasive prenatal testing (NIPT) technique for the detection of chromosomal microdeletions.@*METHODS@#Next-generation sequencing(NGS) and fluorescence in situ hybridization(FISH) were used to analyze the DNA of the fetus. Conventional G-banding was used to analyze the karyotypes of the fetus and its parents. High-throughput sequencing was used to analyze free fetal DNA.@*RESULTS@#NGS analysis has revealed a 4.88 Mb deletion at 15q11.2-q13.1 region in the fetus, which has a 99% overlap with the critical region of Prader-Willi syndrome (Type 2) and Angelman syndrome (Type 2) and encompassed critical genes including SNRPN and UBE3A. NIPT also revealed a 4.6 Mb deletion at 15q12, which was consistent with the results of fetal cord blood and amniotic DNA testing. FISH assay has confirmed the result of NGS. By karyotying, all subjects showed a normal karyotypes at a level of 320~400 bands.@*CONCLUSION@#It is quite necessary to carry out genetic testing on fetuses showing growth restriction. NIPT for fetal chromosomal microdeletions/microduplication syndromes is highly accurate for the diagnosis of Prader-Willi/Angelman syndrome.

Clinical and genetic analysis of three pediatric patients with 15q24 microdeletion syndrome / 中华医学遗传学杂志

OBJECTIVE@#To explore the genetic basis for three patients with development delay and to correlate their clinical phenotypes with genetic findings.@*METHODS@#The karyotypes of the probands and their parents were analyzed by conventional G-banding. Chromosomal microarray analysis (CMA) was used to detect microdeletion and microduplication.@*RESULTS@#No kartotypic abnormality was detected in the patients and their parents. CMA analysis identified a de novo 3.10 Mb deletion on chromosome 15q24.1q24.2 in case 1, a de novo 3.14 Mb deletion at 15q24.1q24.2 in case 2, and a 3.13 Mb deletion at 15q24.1q24.2 in case 3. All deletions have encompassed the CPLX3,SEMA7A and SIN3A genes.@*CONCLUSION@#The three patients were diagnosed with 15q24 microdeletion syndrome. CPLX3,SEMA7A and SIN3A may be the key genes responsible for this syndrome.

Análisis de variación del número de copias y de patrones de metilación en la región 15q11-q13 / Variation analysis of the number of copies and methylene patterns in region 15q11-q13

La región q11-q13 del cromosoma 15 humano es proclive a sufrir alteraciones genéticas. Algunos genes de la región presentan expresión parental diferencial monoalélica, regulada por imprinting (EI). Errores en la regulación del EI, disomías uniparentales (DSU), así como también el cambio en el número de copias genómicas (CNV) producidos por sitios susceptibles de quiebre cromosómico (BP), producen alteraciones en esta región. Las enfermedades más frecuentes asociadas son el síndrome de Prader-Willi, el síndrome de Angelman y el síndrome de microduplicación 15q11-q13. En el presente trabajo analizamos la región 15q11-q13 por Methyl specific-multiplex ligation-dependent probe amplification (MS-MLPA) en 181 muestras de ADN derivadas a nuestro servicio de análisis genético molecular. En este trabajo mostramos que, de las 181 muestras, 39 presentaron alteraciones detectables por MS-MLPA. El 61.5% (24/39) de esas alteraciones detectadas fueron deleciones, el 5.1% (2/39) duplicaciones y el 33.3%(13/39) DSU/EI. Los CNV fueron 4 veces más frecuentes que las DSU/EI (OR = 4; IC 95%: 1.56-10.25) consistente con la literatura. Entre los CNV, dos casos atípicos permiten postular posibles sitios BP que no han sido informados en la literatura previamente.

Human chromosome 15q11-q13 region is prone to suffer genetic alterations. Some genes of this region have a differential monoallelic imprinting-regulated expression pattern. Defects in imprinting regulation (IE), uniparental disomy (UPD) or copy number variation (CNV) due to chromosomal breakpoints (BP) in 15q11-q13 region, are associated with several diseases. The most frequent are Prader-Willi syndrome, Angelman syndrome and 15q11-q13 microduplication syndrome. In this work, we analyzed DNA samples from 181 patients with phenotypes which were compatible with the above-mentioned diseases, using Methyl specific-multiplex ligation-dependent probe amplification (MS-MLPA). We show that, of the 181 samples, 39 presented alterations detectable by MS-MLPA. Of those alterations, 61.5% (24/39) were deletions, 5.1% (2/39) duplications and 33.3% (13/39) UPD/IE. The CNV cases were 4 times more frequent than UPD/IE (OR= 4; IC 95%: 1.56-10.25), consistent with the literature. Among the CNVs, two atypical cases allow to postulate new possible BP sites that have not been reported previously in the literature.

Transformation from promyelocytic leukemia with t (15; 17) ( q22; q21) to acute monocytic leukemia with t (11; 17) (q23; q21) in a case / 中华医学遗传学杂志

<p><b>OBJECTIVE</b>To report on a case of therapy-related acute monocytic leukemia(t-AML) with t(11;17) (q23;q21)/MLL-AF17q after successful treatment for acute promyelocytic leukemia(APL) with t(15;17) (q22;q21)/PML-RARα.</p><p><b>METHODS</b>A MICM method (bone marrow morphology(M), immunophenotype(I), cytogenetics(C), and molecular biology(M)) was used for the diagnosis and classification of the disease at the time of onset and transformation.</p><p><b>RESULTS</b>The patient was initially identified with typical morphology and immunophenotype of APL. She has carried t(15;17)(q22;q21) and PML-RARα fusion gene but was without t(11;17)(q23;q21) or MLL gene abnormalities. After 13 months of successful treatment, she has transformed to AML with typical morphology and immunophenotype. t(11;17)(q23;q21) and MLL-AF17q fusion gene were detected in her bone marrow sample, while no PLZF-RARα fusion gene was detected by real-time quantitative reverse-transcription PCR(RQ-PCR) and fluorescence in situ hybridization(FISH).</p><p><b>CONCLUSION</b>t-AML is a serious complication after successful treatment of APL. t(11;17)(q23;q21) is not specific for the diagnosis of variant APL and can also be detected in t-AML. RQ-PCR and FISH are essential for the diagnosis of such patients.</p>

Phenotypic and genetic analysis of an inv dup(15) case with a BP3:BP3 rearrangement / 中华医学遗传学杂志

<p><b>OBJECTIVE</b>To analyze a case of supernumerary marker chromosome (SMC) with combined genetic techniques and explore its correlation with the clinical phenotype.</p><p><b>METHODS</b>The SMC was analyzed with G-banded karyotyping, multiplex ligation dependent probe amplification (MLPA), fluorescence in situ hybridization (FISH), and single nucleotide polymorphism array (SNP-array).</p><p><b>RESULTS</b>G-banding analysis indicated that the patient has a karyotype of 47,XX,+mar. MLPA showed that there were duplications of proximal 15q. FISH assay using D15Z4 probes indicated that the SMC was a pseudodicentric chromosome derived from chromosome 15. And SNP-array revealed that there were two extra copies of 15q11-13 region spanning from locus 20 161 372 to 29 071 810.</p><p><b>CONCLUSION</b>The duplication of Prader-Willi/Angelman syndrome critical region probably underlies the abnormal phenotype of the inv dup(15) case with a BP3:BP3 rearrangement.</p>

Detection of a patient with ring chromosome 15 by low-coverage massively parallel copy number variation sequencing / 中华医学遗传学杂志

<p><b>OBJECTIVE</b>To explore the genetic cause for a child with developmental delay.</p><p><b>METHODS</b>The karotypes of the child and her parents were analyzed with G-banding analysis. Their genome DNA was analyzed with low-coverage massively parallel copy number variation sequencing (CNV-seq) and verified by single nucleotide polymorphism array (SNP-array).</p><p><b>RESULTS</b>The karyotype of the child was ascertained as 46,XX,r(15)(p13q26.3), while both parents showed a normal karyotype. CNV-seq and SNP-array have identified a de novo 15q26.2-q26.3 deletion in the child with a size of approximately 3.60 Mb.</p><p><b>CONCLUSION</b>The abnormal phenotype of the patient carrying the ring chromosome 15 may be attributed to the presence of the 15q26.2-q26.3 microdeletion. The deletion and haploinsufficiency of the IGF1R gene probably underlie the main clinical features of the patient.</p>

Genetic and prenatal diagnosis of a pregnant women with mental retardation / 中华医学遗传学杂志

<p><b>OBJECTIVE</b>To conduct genetic testing and prenatal diagnosis for a pregnant women with growth retardation, severe mental retardation, and a history of adverse pregnancies.</p><p><b>METHODS</b>G-banded chromosome analysis, fluorescence in situ hybridization (FISH), and whole genome DNA microarray were used to analyze the patient and her fetus.</p><p><b>RESULTS</b>The women was found to be a chimera containing two cell lines with 47 and 46 chromosomes, respectively. Both have involved deletion of 18q21.2q23. FISH analysis suggested that the cell line containing 47 chromosomes has harbored a chromosome marker derived from chromosome 15. The marker has contained chromosome 15p involving the SNRPN locus and part of 15q, which gave rise to a karyotype of 47,XX,del18q21.3,+ish mar D15Z1+ SNRPN+[82]/46,XX,del18q21.3[18]. Whole genome DNA microarray confirmed that a 3.044 Mb fragment from 15q11.2q12 was duplicated, which involved NIPA1, SNRPN and other 17 OMIM genes. Duplication of this region has been characterized by low mental retardation, autism, developmental delay. Meanwhile, there was a 17.992 Mb deletion at 18q21.33q23, which contained 39 OMIM genes including TNFRSF11A and PHLPP1. This fragment was characterized by mental retardation, developmental delay, short stature, and cleft palate. Whole genome microarray analysis confirmed that there was a 17.9 Mb deletion at 18q21.33q23, which has been implemented with mental retardation, general growth retardation, short stature, and cleft palate. After genetic counseling, the family decided to terminate the pregnancy at 21st week.</p><p><b>CONCLUSION</b>Combined chromosome karyotyping, FISH, and whole genome DNA microarray can determine the origin of marker chromosomes and facilitate delineation of its correlation with the clinical phenotype.</p>

Prenatal diagnosis of an unbalanced translocation between chromosome Y and chromosome 15 in a female fetus

We report the prenatal diagnosis of an unbalanced translocation between chromosome Y and chromosome 15 in a female fetus. Cytogenetic analysis of parental chromosomes revealed that the mother had a normal 46,XX karyotype, whereas the father exhibited a 46,XY,der(15)t(Y;15) karyotype. We performed cytogenetic analysis of the father's family as a result of the father and confirmed the same karyotype in his mother and brother. Fluorescence in situ hybridization and quantitative fluorescent-polymerase chain reaction analysis identified the breakpoint and demonstrated the absence of the SRY gene in female members. Thus, the proband inherited this translocation from the father and grandmother. This makes the prediction of the fetal phenotype possible through assessing the grandmother. Therefore, we suggest that conventional cytogenetic and molecular cytogenetic methods, in combination with family history, provide informative results for prenatal diagnosis and prenatal genetic counseling.

Genetic analysis of a patient featuring developmental delay and mental retardation / 中华医学遗传学杂志

<p><b>OBJECTIVE</b>To explore the genetic cause for a child featuring developmental delay and mental retardation.</p><p><b>METHODS</b>The child was analyzed with G-banded karyotyping and an Illumina Human CytoSNP-12 Beadchip.</p><p><b>RESULTS</b>The father of the patient had a normal karyotype. The mother had a karyotype of 46, XX, t(12;15)(p13.3;q13). The child had a karyotype of 45, XY, der(12)t(12;15)(p13.3;q13)mat, -15. SNP array analysis showed that the child has deletions in 12p13.31-p13.33 and 15q11.2-q13.2. But no deletion or duplication was detected in his mother.</p><p><b>CONCLUSION</b>The unbalanced translocation involving chromosomes 12 and 15 probably accounts for the mental retardation in the child. SNP array is useful for the detection of chromosomal rearrangements and genetic counseling.</p>

Acute promyelocytic leukaemia with translocations of t(15;17)(q22;q21) and rob(13;21): a case report and literatures review / 中华血液学杂志

<p><b>OBJECTIVE</b>To report an acute promyelocytic leukaemia (APL) case with translocation of rob (13;21) t(15;17) (q22;q21) and review its clinical and laboratory characteristics.</p><p><b>METHODS</b>Based on routine karyotype analysis and bone marrow morphology, we further used double color double fluorescent in situ hybridization (DCDF-FISH) and reverse transcriptase PCR (RT-PCR) to examine the patient's abnormities on cytogenetic and molecular biology, and reveal the clinical characteristics of this rare translocation also from the related literatures.</p><p><b>RESULTS</b>The clinical manifestation and bone marrow morphology examination of this patient were in accordance with pathologic feature of APL. On first visit, immunophenotyping analysis showed positive myeloid markers. Through R-banding, the patient's karyotype was confirmed as 45, XX, rob(13;21) t(15;17) (q22;q21) [6]/45, XX, rob(13;21) [14]. FISH results showed that 68.9% cells were typical t(15;17) pattern. The positive rates of fusion gene of PML-RARα detected by RT-PCR was 25.8%. Patient was treated by induction and consolidation therapy, the karyotype was 45, XX, rob(13;21 )[20] after complete remission. The positive rate of fusion gene of PML-RARα by FISH and its level were 2.5% and 0.003% respectively.</p><p><b>CONCLUSION</b>APL with rob (13;21) t(15;17) (q22;q21) was very rare, which was accorded with clinical and laboratory characteristics of APL. The value of chromosome abnormality as a prognostic marker in APL needs to be further observed..</p>

Prenatal diagnosis for a women with a suspected birth history of Angelman syndrome / 中华医学遗传学杂志

<p><b>OBJECTIVE</b>To verify the diagnosis of Angelman syndrome(AS) in a proband in order to provide prenatal diagnosis for his family.</p><p><b>METHODS</b>Array comparative genome hybridization(array-CGH) and fluorescence in situ hybridization(FISH) on metaphase chromosomes were performed.</p><p><b>RESULTS</b>The karyotype of the proband was normal, and a regional deletion of 15q11.1-11.2 was detected by array-CGH. FISH analysis has confirmed loss of heterozygosity in 15q11.2. No positive results were obtained by array-CGH or karyotype analysis. Amniotic fluid sample was taken from the proband's mother upon her subsequent pregnancy. The karyotype of the fetus was normal, but SNP microarray chip analysis has identified loss of heterozygosity in 8p23.1-p22. As no abnormality was observed by ultrasound and other prenatal examinations, the pregnancy was recommended to continue to full-term, and a healthy infant was born.</p><p><b>CONCLUSION</b>Clinically suspected AS can be diagnosed by array-CGH and FISH. The result may facilitate accurate genetic counseling and prenatal diagnosis for the affected family.</p>

Birth seasonality in Korean Prader-Willi syndrome with chromosome 15 microdeletion

PURPOSE: Prader-Willi syndrome (PWS) is a well-known genetic disorder, and microdeletion on chromosome 15 is the most common causal mechanism. Several previous studies have suggested that various environmental factors might be related to the pathogenesis of microdeletion in PWS. In this study, we investigated birth seasonality in Korean PWS. METHODS: A total of 211 PWS patients born from 1980 to 2014 were diagnosed by methylation polymerase chain reaction at Samsung Medical Center. Of the 211 patients, 138 were born from 2000-2013. Among them, the 74 patients of a deletion group and the 22 patients of a maternal uniparental disomy (UPD) group were compared with general populations born from 2000 using the Walter and Elwood method and cosinor analysis. RESULTS: There was no statistical significance in seasonal variation in births of the total 211 patients with PWS (chi2=7.2522, P=0.2982). However, a significant difference was found in the monthly variation between PWS with the deletion group and the at-risk general population (P<0.05). In the cosinor model, the peak month of birth for PWS patients in the deletion group was January, while the nadir occurred in July, with statistical significance (amplitude=0.23, phase=1.2, low point=7.2). The UPD group showed the peak birth month in spring; however, this result was not statistically significant (chi2=3.39, P=0.1836). CONCLUSION: Correlation with birth seasonality was identified in a deletion group of Korean PWS patients. Further studies are required to identify the mechanism related to seasonal effects of environmental factors on microdeletion on chromosome 15.

Isodicentric Chromosome 15 Syndrome in a Korean Patient With Cafe-au-lait Spots

No abstract available.

Griscelli syndrome type 2: a novel mutation in RAB27A gene with different clinical features in 2 siblings: a diagnostic conundrum / 소아과

Griscelli syndrome type 2 (GS2) is a rare autosomal recessive disease caused by mutations in the RAB27A gene. It is characterized by cutaneous hypopigmentation, immunodeficiency, and hemophagocytic lymphohistiocytosis. We describe 2 brothers who had GS2 with clinically diverse manifestations. The elder brother presented with a purely neurological picture, whereas the younger one presented with fever, pancytopenia, hepatosplenomegaly, and erythema nodosum. Considering that cutaneous hypopigmentation was a common feature between the brothers, genetic analysis for Griscelli syndrome was performed. As the elder sibling had died, mutation analysis was only performed on the younger sibling, which revealed a novel homozygous mutation in the RAB27A gene on chromosome 15 showing a single-base substitution (c.136T>A p.F46I). Both parents were heterozygous for the same mutation. This confirmed the diagnosis of GS2 in the accelerated phase in both siblings. The atypical features of GS2 in these cases are a novel mutation, isolated neurological involvement in one sibling, association with erythema nodosum, and 2 distinct clinical presentations in siblings with the same genetic mutation.

A Nine-Month-Old Boy With Isodicentric Chromosome 15: A Case Report

Isodicentric chromosome 15 [idic(15)] is a rare chromosomal abnormality that occurs due to inverted duplication of chromosome 15q. It is associated with many clinical findings such as early central hypotonia, developmental delay, cognitive dysfunction, autism spectrum disorders, and seizure. Delayed development is a common problem referred to pediatric rehabilitation clinics. A 9-month-old boy with delayed development was referred to our clinic for assessment and treatment. On chromosomal analysis, he was diagnosed as idic(15) syndrome with 47,XY,+idic(15)(q12) on karyotyping. Herein we describe his clinical manifestations and provide a brief review of the related literature.

Analysis of small supernumerary marker chromosome 15q11 in four infertile males / 中华医学遗传学杂志

<p><b>OBJECTIVE</b>To delineate the origins of small supernumerary marker chromosomes (sSMCs) identified in 4 infertile males.</p><p><b>METHODS</b>The sSMCs were analyzed with combined G-banding, N-banding, multiplex ligation-dependent probe amplification (MLPA), fluorescence in situ hybridization (FISH) and single nucleotide polymorphisms array (SNP-array) techniques.</p><p><b>RESULTS</b>G-banding analysis has suggested a 46,X,-Y,+mar karyotype in all of the 4 cases. N-banding revealed that all of the sSMCs have possessed two satellites located on both sides. By MLPA, 1 patient showed copy number gains for 15q11.2 region. SNP-array analysis suggested that all had duplication for 15q11.1-q11.2 region, spanning 3.06 Mb, 0.9118 Mb, 1.728 Mb and 0.287 Mb, respectively. By FISH analysis, all of the sSMCs showed two hybridization signals, indicating that they were dicentric chromosomes.</p><p><b>CONCLUSION</b>In all of the four cases, the marker chromosomes have derived from chromosome 15 and were bisatellited and dicentric, which gave rise to a karyotype of 47,XY,+ish,inv dup(15)(q11)(D15Z4++). sSMC 15q11 therefore may be a major cause for male infertility.</p>

Combined Genome-Wide Linkage and Association Analyses of Fasting Glucose Level in Healthy Twins and Families of Korea

This study was undertaken to identify genetic polymorphisms that are associated with the risk of an elevated fasting glucose (FG) level using genome-wide analyses. We explored a quantitative trait locus (QTL) for FG level in a genome-wide study from a Korean twin-family cohort (the Healthy Twin Study) using a combined linkage and family-based association analysis approach. We investigated 1,754 individuals, which included 432 families and 219 pairs of monozygotic twins. Regions of chromosomes 2q23.3-2q31.1, 15q26.1-15q26.3, 16p12.1, and 20p13-20p12.2, were found to show evidence of linkage with FG level, and several markers in these regions were found to be significantly associated with FG level using family-based or general association tests. In particular, a single-nucleotide polymorphism (rs6138953) on the PTPRA gene in the 20p13 region (combined P = 1.8 x 10(-6)) was found to be associated with FG level, and the PRKCB1 gene (in 16p12.1) to be possibly associated with FG level. In conclusion, multiple regions of chromosomes 2q23.3-2q31.1, 15q26.1-15q26.3, 16p12.1, and 20p13-20p12.2 are associated with FG level in our Korean twin-family cohort. The combined approach of genome-wide linkage and family-based association analysis is useful to identify novel or known genetic regions concerning FG level in a family cohort study.