Identificación de aberraciones cromosómicas en una población infantil costarricense con discapacidad intelectual idiopática / Identification of chromosomal aberrations in a Costa Rican children population with idiopathicintellectual disability

Resumen La prevalencia mundial de la discapacidad intelectual (DI) es del 3 %. Una de las causas más comunes de DI de origen genético son las aberraciones cromosómicas, las cuales resultan fácilmente detectables mediante un cariotipo. Sin embargo, muchas de estas pasan desapercibidas durante el análisis citogenético convencional debido a su tamaño. Estas pequeñas alteraciones se pueden localizar en los subtelómeros y se ha observado que, cuando es así, constituyen una razón importante de DI en pacientes que carecen de un diagnóstico de causalidad. En este estudio de tipo observacional, se utilizó la técnica MLPA con el objetivo de determinar la frecuencia de aberraciones cromosómicas submicroscópicas en los subtelómeros en una población infantil con DI de origen desconocido. Se examinaron 70 muestras de forma exitosa y se obtuvo un caso con una microduplicación en el subtelómero 17p, para una frecuencia del 1,4 %. También, se realizó el análisis citogenético en 33 muestras y se encontró un caso con una aberración cromosómica detectable al microscopio, para una frecuencia del 3 %. El porcentaje de aberraciones cromosómicas subteloméricas fue menor al esperado en comparación con estudios similares. Finalmente, se concluyó que el cariotipo y la técnica MLPA se complementan para el abordaje de personas con DI de origen desconocido.

Abstract The prevalence of intellectual disability (ID) in the global population is 3%. One of the most frequent cause of ID are chromosome aberrations, which are easily detected by a karyotype. However, many of these maygoundetected during a conventional cytogenetic analysis because of their length.These small alterations can be localized in the subtelomeres and it has been observed that when localized there, they are an important cause of ID in patients without a causality diagnostic. In this observational study, we use the MLPA technique for the purpose of identifying the frequency of submicroscopicsubtelomere chromosomal aberrations in a population of people with ID of unknown origin. 70 samples were successfully analyzed with MLPA and we found one case with a microduplication in the 17p subtelomere for a frequency of 1,4%. Also,the karyotype was performed in 33cases, and we foundone case with a chromosome aberration that can be detect by microscope for a frequency of 3%. The subtelomeric chromosome aberration frequency was lower than expected as we compare our results with similar studies. Finally, with this work we conclude that the karyotype and the MLPA technique complement each other for approaching people with ID of unknown origin.

A de novo marker chromosome 15 in a child with isolated developmental delay

We report a rare case of a 14-month-old male child who was referred for developmental delay. Clinical examination revealed a hypotonic infant with speech delay and no dysmorphic features. The banding cytogenetics revealed a small supernumerary marker chromosome. Upon silver staining, the marker showed the presence of satellite regions on either ends. Further, analysis using fluorescence in situ hybridization on marker chromosome revealed its origin from chromosome 15.

Reflection of a case misdiagnosed as trisomy 21 syndrome by G-banded chromosomal karyotyping analysis / 中华医学遗传学杂志

Objective@#To emphasize the clinical significance of copy number variations (CNVs) detection by describing a case misdiagnosed as trisomy 21 syndrome by G-banded chromosomal karyotype analysis.@*Methods@#A girl with obesity and short stature was diagnosed as trisomy 21 syndrome by G-banded chromosomal karyotype analysis. Considering the discrepancy of her karyotype with her phenotype, genomic CNVs was detected by next-generation sequencing and the result was verified by quantitative PCR (qPCR).@*Results@#A microduplication of 16p11.2: 29 642 339-29 775 631 (133.292 kb) was detected. qPCR assay for QPRT and SPN located in the duplicated region confirmed the finding of CNVs assay. Meanwhile, her parents did not present similar duplication in 16p11.2.@*Conclusion@#The 16p11.2 microduplication was a novel genomic structural variation in the girl, though it may not be associated with her clinical manifestations. Chromosomal microarray or next-generation sequencing-based CNVs detection can accurately determine the origin of small supernumerary marker chromosome and reduce the chance of misdiagnosis.

Identification of cryptic structural chromosomal aberrations in parents through detection of copy number variations in miscarriage tissues / 中华医学遗传学杂志

Objective@#To explore the genetic cause for abnormal pregnancies through detecting chromosomal copy number variations (CNVs) in abortic tissues by next generation sequencing (NGS).@*Methods@#NGS technique was used to detect CNVs in abortion tissues. Parental chromosomal karyotypes were predicted based on the results. The aberrant chromosomal segments of the parents were accurately mapped by G-banding karyotyping analysis and fluorescence in situ hybridization (FISH).@*Results@#In addition to numerical chromosomal aberrations, 12 microdeletion/microduplications were detected by NGS. For 8 families where both parents accepted chromosomal karyotyping, 4 carriers of chromosomal abnormalities were identified. One marker chromosome was missed by karyotyping analysis, and a mother was confirmed to carry a cryptic balanced translocation by FISH.@*Conclusion@#NGS can facilitate detection of cryptic chromosomal translocations in couples with repeated pregnancy failure and is of great value for detecting abnormal CNVs for its high sensitivity.

Prenatal diagnosis of a fetus with two small supernumerary marker chromosomes / 中华医学遗传学杂志

Objective@#To explore the clinical significance of a prenatal case with two small supernumerary marker chromosomes (sSMC) through identification of their origins.@*Methods@#G-banding chromosomal karyotyping analysis were carried out on fetal amniotic fluid sample and peripheral blood samples from both patients. Fluorescence in situ hybridization (FISH) and single nucleotide polymorphism-array (SNP-array) were used to analyze the component and size of the sSMCs.@*Results@#The karyotype of the fetus was determined as 47, XX, + mar[53]/48, XX, + 2 mar[31]/46, XX[14]. SNP-array has revealed four copies of chromosome 2q11.1q11.2 with a size of 2.6 Mb and three copies of 10p11.23q11.23 with a size of 20.6 Mb. The results was confirmed by FISH.@*Conclusion@#A rare chromosomal abnormality with two sSMCs was identified by combined karyotype analysis, SNP-array and FISH, which provided valuable information for prenatal diagnosis.

A boy with 46,X,+mar presenting gynecomastia and short stature

A 15-year-old boy was referred due to gynecomastia and short stature. He was overweight and showed the knuckle-dimple sign on the left hand, a short fourth toe on the left foot, and male external genitalia with a small phallus. His levels of estradiol and follicle-stimulating hormone were increased, and his testosterone concentration was normal. Other hormonal tests were within the normal range. Radiographs showed short fourth and fifth metacarpals and fourth metatarsal bones. The karyotype was reported as 46,X,+mar, and the marker chromosome was shown to originate from the Y chromosome, which was identified by fluorescence in situ hybridization. Polymerase chain reaction and direct sequencing were used to clarify the deleted loci of the Y chromosome by making use of Y-specific sequence-tagged sites (STSs). The sex-determining region Y and centromere were verified, and there were microdeletions on the long arm of the Y chromosome. The azoospermia factor (AZF) b region was partially deleted, and AZFa and AZFc were completely deleted. Two STS probes of sY143 and the Y chromosome RNA recognition motif in AZFb showed positive signals corresponding to Yq11.223. The karyotype of the patient was interpreted as 46,X,der(Y)del(Y)(q11.21q11.222)del(Y)(q11.23qter). Herein, we report a rare case of a boy presenting with gynecomastia and short stature with 46, X, +mar, which originated from the Y chromosome, which was identified to have Yq microdeletions.

Small supernumerary marker chromosome and chromosome 18p abnormalities / 中华实用儿科临床杂志

Humans typically have 22 pairs of autosomal chromosomes in cells,and a pair of sex chromosomes.Some individuals have an extra,autosomal chromosome called a small supernumerary marker chromosome (sSMC).sSMC is a structurally abnormal chromosome fragment.The fragments are too small and no-specific banding pattern to be identified by conventional banding cytogenetic analysis.Array-based comparative genomic hybridization (aCGH),fluorescence in situ hybridization (FISH) or other molecular biological methods are necessary for the diagnosis.This article summarized the karyotype,pathogenesis,and the clinical manifestations of the sSMC-related chromosome 18p abnormalities.The patients with sSMC usually presented with abnormal chromosome syndrome.Some syndromes are relative common,such as Pallister-Killian syndrome,isochromosome 18p syndrome,Cat eye syndromes or Emanuel syndrome.sSMC is considered to be the frequent cause of mental retardation.The patients have no specific symptoms.With the progress of molecular cytogenetics,more sSMC has been identified.Genetic counseling and prenatal diagnosis are important to prevent sSMC.Molecular cytogenetic techniques are necessary to the diagnosis.

Application of aCGH technology in diagnosing small supernumerary marker chromosome / 国际检验医学杂志

Objective To explore the clinical application of array comparative genomic hybridization (aCGH) and karyotype a-nalysis in the prenatal evaluation of fetal with small supernumerary marker chromosome (sSMC) .Methods One case was indenti-fied with de novo small supernumerary marker chromosome .G-banding analysis indicated that the fetus had a karyotype of 47 , XY ,+Mar .aCGH was used to define the precise location and size of de novo chromosome .Results aCGH revealed that there was 2 .03 Mb duplication from 15q11 .1-q11 .2 in the fetus .aCGH revealed the presence of small supernumerary marker chromosome . Conclusion The technologies of aCGH can be used for identifying the origin of small supernumerary marker chromosome and defi-ning the loci of the chromosome .Combined with the karyotype analysis ,it can be applied to genetics analysis and prenatal diagnosis .

Chromosomal abnormalities in couples with repeated fetal loss: An Indian retrospective study.

BACKGROUND: Recurrent pregnancy loss is a common occurrence and a matter of concern for couples planning the pregnancy. Chromosomal abnormalities, mainly balanced rearrangements, are common in couples with repeated miscarriages. PURPOSE: The purpose of this study is to evaluate the contribution of chromosomal anomalies causing repeated spontaneous miscarriages and provide detailed characterization of a few structurally altered chromosomes. MATERIALS AND METHODS: A retrospective cytogenetic study was carried out on 4859 individuals having a history of recurrent miscarriages. The cases were analyzed using G‑banding and fluorescence in situ hybridization wherever necessary. RESULTS: Chromosomal rearrangements were found in 170 individuals (3.5%). Translocations were seen in 72 (42.35%) cases. Of these, reciprocal translocations constituted 42 (24.70%) cases while Robertsonian translocations were detected in 30 (17.64%) cases. 7 (4.11%) cases were mosaic, 8 (4.70%) had small supernumerary marker chromosomes and 1 (0.6%) had an interstitial microdeletion. Nearly, 78 (1.61%) cases with heteromorphic variants were seen of which inversion of Y chromosome (57.70%) and chromosome 9 pericentromeric variants (32.05%) were predominantly involved. CONCLUSIONS: Chromosomal analysis is an important etiological investigation in couples with repeated miscarriages. Characterization of variants/marker chromosome enable calculation of a more precise recurrent risk in a subsequent pregnancy thereby facilitating genetic counseling and deciding further reproductive options.

Another small supernumerary marker chromosome derived from chromosome 9 in a Klinefelter patient / Otro cromosoma marcador supernumerario pequeño derivado del cromosoma 9 en un paciente con el síndrome de Klinefelter

Marker chromosomes are very rare in Klinefelter patients and phenotypic findings are related to the affected chromosomal region. The phenotypic effects of small supernumerary marker chromosomes (sSMC) range from multiple malformations/mental retardation to no effect (ie a normal phenotype). This wide spectrum of phenotypes is due to the origin, structure and gene content of the marker chromosome. The first Klinefelter case with sSMC 9 was published by Liehr et al in 2005. The present case was referred for chromosomal analysis because of dysmorphic features, speech delay and mild mental retardation. Conventional cytogenetic analysis revealed the 47 XXY karyotype in 17 metaphases and the 48 XXY + marker karyotype in eight metaphases. Fluorescence in situ hybridization (FISH) analysis to identify the marker chromosome was performed using the LSI p16 (9p21) Spectrum Orange/CEP 9 SpectrumGreen Probe (Vysis CDKN2A/CEP 9 FISH Probe) and partial trisomy 9 mosaicism was confirmed in this patient. To our knowledge, this is the second case of Klinefelter syndrome with a small supernumerary marker chromosome derived from chromosome 9.

Los cromosomas marcadores son muy raros en los pacientes de Klinefelter, y los hallazgos fenotípicos se relacionan con la región cromosomática afectada. Los efectos fenotípicos de los cromosomas marcadores supernumerarios pequeños (sSMC) van desde el retraso mental y las malformaciones múltiples hasta la ausencia total de efectos (es decir, un fenotipo normal). Este amplio espectro de fenotipos se debe al origen, estructura y contenido del gen del cromosoma marcador. El primer caso de síntoma Klinefelter con sSMC 9 fue publicado por Liehr et al en 2005. El caso presente fue remitido para análisis cromosomático debido a rasgos dismórficos, retraso del habla, y retardo mental ligero. El análisis citogenético convencional reveló el cariotipo 47 XXY en 17 metafases y el cariotipo marcador 48 XXY+ en ocho metafases. El análisis mediante hibridación fluorescente in situ (FISH) para identificar el cromosoma marcador se realizó usando la sonda LSI p16 (9p21) Spectrum Orange/CEP 9 SpectrumGreen Probe (Vysis CDKN2A/CEP 9 FISH Probe). Un mosaicismo de trisomía 9 parcial fue confirmado en este paciente. Hasta donde sabemos, éste es el segundo caso de síndrome de Klinefelter con un cromosoma marcador supernumerario pequeño derivado del cromosoma 9.

A case of isodicentric chromosome 15 presented with epilepsy and developmental delay / 소아과

We report a case of isodicentric chromosome 15 (idic(15) chromosome), the presence of which resulted in uncontrolled seizures, including epileptic spasms, tonic seizures, and global developmental delay. A 10-month-old female infant was referred to our pediatric neurology clinic because of uncontrolled seizures and global developmental delay. She had generalized tonic-clonic seizures since 7 months of age. At referral, she could not control her head and presented with generalized hypotonia. Her brain magnetic resonance imaging scans and metabolic evaluation results were normal. Routine karyotyping indicated the presence of a supernumerary marker chromosome of unknown origin (47, XX +mar). An array-comparative genomic hybridization (CGH) analysis revealed amplification from 15q11.1 to 15q13.1. Subsequent fluorescence in situ hybridization analysis confirmed a idic(15) chromosome. Array-CGH analysis has the advantage in determining the unknown origin of a supernumerary marker chromosome, and could be a useful method for the genetic diagnosis of epilepsy syndromes associated with various chromosomal aberrations.

Anomalías cromosómicas en ambos padres de un niño con defectos congénitos múltiples: reporte de caso / Chromosomal abnormalities in both parents of a child with multiple congenital defects: case report

Se presenta el caso de una pareja con antecedente de hijo portador de defectos congénitos, fallecido a los 2 días. No se realizó cariotipo al niño fallecido, quien es el producto del 3º embarazo de madre de 35 años y padre de 45 años, ambos aparentemente sanos y no con sanguíneos. No refieren antecedentes familiares de defectos congénitos, no hay antecedentes patológicos ni de ingestión de medicamentos durante el embarazo. El estudio cromosómico de la pareja se realizó en linfocitos de sangre periférica. En todas las células analizadas de la madre se observó la heterocromatina del cromosoma 9 aumentada, en el 2% de las células, una translocación entre los cromosomas 2 y 22 y también en el 2% un isocromosoma para el brazo largo del cromosoma 1. En el padre, el 7,5% de las células analizadas, se observó la presencia de un cromosoma marcador. El cariotipo de la madre fue 46,XX,9qh+,t(2;22),i(1q); y del padre, XY/47,XY+mar.Si bien el 9qh+ es considerado variante cromosómica normal y sin repercusión clínica, esta condición ha sido hallada en parejas con problemas de esterilidad e infertilidad. La translocación y el isocromosoma hallados en la paciente, son alteraciones cromosómicas más severas, fueron observadas en muy bajo porcentaje,constituyen rearreglos cromosómicos que conducen a la formación de gametos desequilibrados. Sería más factible considerar al cromosoma marcador supernumerario como responsable de la malformación en el niño. Con estos antecedentes, se resalta la indicación médica del estudio citogenético en padres de pacientes portadores de malformaciones múltiples, para el asesoramiento genético familiar correspondiente.

This is the case of a couple with a child carrier of congenital defects, deceased at the second day after birth. The karyotype the deceased child was not made and the child was product of the third pregnancy of a mother of 35 years old and a father of 45 years old, both apparently healthy and non-consanguineous. Both parents did not refer any family history of birth defects, pathological background or medicines intake during pregnancy. The couples karyotype was performed on lymphocytes isolated from peripheral blood. All cells from the mother showed and increased heterochromatin on chromosome 9; 2% showed a translocation between chromosomes 2 and 22; and another 2% showed anisochromosome for the long arm of chromosome 1. In the father, 7.5% of the cells showed the presence of a marker chromosome. The mother´s kariotype was 46,XX,9hq+,t(2;22),i(1q) and the father´s was 46,XY/47,XY+mar. While 9qh+ chromosomal is considered normal with no clinical consequences, this condition has been found in couples with infertility and sterility problems. The translocation and the isochromosome found at a very low percentage are considered the most severe chromosomal abnormalities that lead to the production of unbalanced gametes. It would be more feasible to consider the supernumerary marker chromosome as responsible of the birth defects in the child. This background emphasizes the importance of the medical indication of cytogenetic studies in parents of children carriers of multiple malfomrations = for the corresponding genetic counseling.

Supernumerary Marker Chromosome in a Child with Microcephaly and Mental Retardation.

A de novo supernumerary marker chromosome (SMC) was identified in a 13- month-old girl who presented with microcephaly and mild mental retardation. On further characterization by oligo-nucleotide array-comparative genomic hybridization [array-CGH], the SMC was confirmed to be 18p.

A Case of Partial Trisomy 2p23-pter Syndrome with Trisomy 18p Due to a de novo Supernumerary Marker Chromosome / 대한진단검사의학회지

Partial trisomy 2p is a rare but relatively well-defined syndrome with distinctive clinical features, including marked psychomotor delay, dysmorphic face, and congenital heart disease. The phenotype of trisomy 18p is variable, from normal appearance to moderate mental retardation. Most cases of trisomy 2p and trisomy 18p result from the inheritance of an unbalanced segregant from a balanced parental translocation or due to de novo duplication. Here, we present the first report of a combined partial trisomy 2p and trisomy 18p due to a supernumerary marker chromosome (SMC). The final karyotype of the patient was 47,XX,+der(18)t(2;18)(p23.1;q11.1)[22]/46,XX[8]. The patient had typical dysmorphic features of partial trisomy 2p23-pter syndrome and congenital heart disease. SMCs are remarkably variable in euchromatic DNA content and mosaicism level. The precise identification of the origin and composition of SMCs is essential for genotype-phenotype correlation and genetic counseling.

Familial small supernumerary marker chromosome (sSMC) (14)(:p11-q11:) in a child with translocation down syndrome.

We report a case of familial small supernumerary marker chromosome (sSMC) in a child with translocation Down syndrome (DS)and mother.The GTG-banded chromosomal analysis of DS child revealed 47,XY,+21,+mar and mother karyotype was 47,XX,+mar.The GTG-banded sSMC had a similar morphology of small acrocentric chromosomes .Fluorescence in situ hybridization (FISH)evaluation of sSMC using centromere probes(13/21,14/22,22)confirmed sSMC as derivative chromosome 14.The sSMC was not specifically stained with whole chromosome paint and arm-specific probes for chromosome 14;thus it has been described as der(14)(:p11-q11:).The phenotypic changes were not evident, may be due to trisomy condition in the child or the sSMC contain repetitive sequences.

A case of prenatally diagnosed Non-15, Non-22 marker chromosome / 대한산부인과학회지

Midtrimester genetic amniocentesis is an important diagnostic tool in prenatal genetic diagnosis and counseling. We can identify karyotypes with metaphase chromosome analysis of cultured amniocytes. Marker chromosomes are defined as unidentified structurally abnormal chromosomes. Incidence of marker chromosomes in the previous reported studies was 0.6-1.5/1,000. They occurred more frequently with advanced maternal age. Ascertainment of chromosomal origin is important because it may be associated with malformation and developmental abnormalities. Recently, identification of the origin and composition of marker chromosomes has been made possible by the use of fluorescent in situ hybridization (FISH). Most marker chromosomes are known to be originated from chromosome 15 or 22, X, Y. We have experienced a case of non-15, non-22 marker chromosome prenatally detected in amniocentesis and FISH, so we reported it with a brief review of literature.

Hidden Y Chromosome and Marker Chromosome Identification by FISH (Fluorescence in Situ Hybridization) in Turner Syndrome / 대한산부인과학회잡지

OBJECTIVE: To assess the effectiveness of hidden Y chromosome and marker chromosome identification by FISH (Fluorescence in Situ Hybridization) in Turner syndrome. METHODS: Data was collected retrospectively from 25 patients with or without marker chromosome confirmed Turner syndrome by chromosomal study in Department of Obstetrics and Gynecology, Yonsei University Medical Center. FISH was performed on all patients for hidden Y chromosome and marker chromosome identification. RESULTS: FISH showed the origin of marker chromosome in 9 patients whose karyotypes were 45,X/ 46,X+mar, 5 patients were positive for SRY gene. Of 16 patients whose karyotypes were 45,X or 45,X/46,XX, there was no hidden Y chromosome indentification by FISH. CONCLUSION: FISH for marker chromosome identification in Turner syndrome is a rapid and effective procedure. But to enable widespread use of hidden Y chromosome identification by FISH in Turner syndrome, further studies involving many cases are warranted.

Detection of Y Chromosome-specific Sequences in Patients with Turner Syndrome / 대한산부인과학회잡지

Existence of Y derived chromosome in Turner patients is significant due to the risk of gonadoblastoma development, but cytogenetic analysis may fail to detect low levels of Y chromosomal materials. Recent studies using PCR based methods showed higher sensitivity to detect Y-specific sequences, in patients who were Y chromosome-negative cytogenetically. In this study PCR was performed on 44 Turner patients with no Y chromosome by cytogenetic analysis to detect the SRY, AMELY, ZFY, and DYZ1 sequences. Of seven patients whose karyotypes were 45,X/46,X,+mar, three patients were positive for SRY, ZFY, and AMELY. DYZ1 sequences was negative in them. And any of SRY, ZFY, AMELY, and DYZ1 sequences was detected in the remaining 37 patients. This result shows that PCR analysis for Y-specific sequences in Turner patients, especially in patients who have marker chromosome is a significant effort.

A Case of Identification of Marker Chromosome by comparative genomic hybridization and fluorescence in situ hybridization / 대한임상병리학회지

Comparative genomic hybridization (CGH) has been used to identify deletions and amplifications, particularly in neoplastic samples. CGH provides a new possibility searching genomes for imbalances of genetic material. We described the combined use of CGH and fluorescence in situ hybridization (FISH) to identify the origin of a marker chromosome in a child with mental retardation. Giemsa banding of metaphases from cultured lymphocytes showed a marker chromosome. The Karyotype was 47,XX,+mar. CGH revealed that the additional material originated from 15q. FISH confirmed this finding with whole chromosome paint for chromosome 15 and with a D15S10 (15q11-13) probe. This case demonstrates the efficient use of CGH and confirmatory FISH for the identification of chromosomal material of unknown origin.

Construction of DNA Painting Probe for Transldegrees Cation Region of a Marker Chromosome by Chromosome Microdissection / 대한암학회지

PURPOSE: Chromosome microdissection has been recommended as a technology to overcome the limited problems of conventional cytogenetic analysis and is a direct approach to isolate DNA from specific interesting region of chromosome. KUMA-1 cell line has a specific reserved chromosome abnormality during prdegrees Cess from primary cancer culture to continuous cell line development, der(2)t(2;?)(qter;?). So molecular analysis for transldegrees Cation region of der(2) may be helpful to understand pathogenesis of this primary cancer. The aim of this study was to develop painting probe for the transldegrees Cation region for molecular study in future about transldegrees Cation region of der(2) of KUMA-1 cell line. MATERIALS AND METHODS: KUMA-1 cell line was derived from a squamous cell carcinoma of urinary bladder. The transldegrees Cation breakpoint region of der(2) appeared in KUMA-1 cell line was microdissected and dissected chromosome segments were amplified by PCR reaction. Fluorescent in situ hybridization was conducted on KUMA-1 metaphase cells with the probe generated from PCR product to confirm the construction of painting probe containing the transldegrees Cation breakpoint of der(2). RESULTS: Painting probe was hybridized to the metaphase chromosome of KUMA-1 cell line and two fluorescent signals were mapped to the transldegrees Cation forming chromosomal region of der(2). CONCLUSION: It was possible to construct the painting probe for the transldegrees Cation region of der (2) by chromosome microdissection.