Turner syndrome associated with Down syndrome: about a case / Síndrome Turner asociado a síndrome Down: a propósito de un caso

The coexistence of double aneuploidy of Down and Turner syndromes is rare; most cases have been due to double mitotic errors. The objective of the study was to report a case with monosomy of the X chromosome and trisomy of chromosome 21, in mosaic variety, highlighting the phenotypic effect that the presence of different chromosomal abnormalities can produce and compare with those reported in the literature. A 10-year-old Ecuadorian female, born to a multipregnant mother with 46 years at conception, is seen in consultation with a predominant clinical phenotype of Down syndrome, associated with menarche, presence of pubic and axillary villu, where a karyotype is verified 45 X[7]/47XX+ 21 [3]/46, X, der (X)(: p11.1-> q11.1)[1]/46,XX [1]. The present case is a double Turner-Down aneuploidy, with predominantly X monosomy cell line, who shows important mental retardation and some signs of puberal development not usually in Turner syndrome. These features highlight the clinical importance of doing a karyotype in mental retardation cases and searching low mosaics of another aneuploidies in atypical cases. Its complex chromosomal formula and support with molecular cytogenetics allowed diagnostic confirmation and genetic counseling.

La coexistencia de doble aneuploidía de los síndromes de Down y Turner es rara; la mayoría de los casos se han debido a dobles errores mitóticos. Reportar un caso con trisomía del cromosoma 21 y monosomía del cromosoma en X, en variedad mosaico, que curiosamente presenta un despertar puberal precoz y comparar con los reportados en la literatura. Paciente ecuatoriana de sexo femenino, de 10 años de edad, nacida de madre multigesta con 46 años a la concepción, que es vista en consulta con fenotipo clínico predominante de Síndrome Down, asociado a menarquia y telarquia, donde se constata un cariotipo. El presente caso es el primero informado de mosaicismo de doble aneuploidía de Turner-Down asociado con un despertar puberal precoz. Su fórmula cromosómica compleja y el apoyo con la citogenética molecular permitió la confirmación diagnostica y la asesoría genética.

Genetic testing and analysis of 2 cases of trisomy 11 mosaicism / 南方医科大学学报

Trisomy 11 mosaicism is clinically rare, for which making diagnostic and treatment decisions can be challenging. In this study, we used noninvasive prenatal testing, chromosome karyotype analysis, chromosome microarray analysis, copy number variation sequencing and fluorescence in situ hybridization for detecting trisomy 11 mosaicism in two cases and provided them with genetic counseling. In one of the cases, the fetus with confined placental mosaicism trisomy 11 presented with severe growth restriction and a placental mosaic level of 44%, and pregnancy was terminated at 25+3 weeks of gestation. In the other case with true low-level fetal mosaicism of trisomy 11, the pregnancy continued after exclusion of the possibility of uniparental disomy and structural abnormalities and careful prenatal counseling. The newborn was followed up for more than one year, and no abnormality was found. Noninvasive prenatal testing is capable of detecting chromosomal mosaicism but may cause missed diagnosis of true fetal mosaicism. For cases with positive noninvasive prenatal testing but a normal karyotype of the fetus, care should be taken in prenatal counseling and pregnancy management.

Whole exome sequencing analysis of a patient with 45,X/46,XY mosaicism and autism spectrum disorder / 中华医学遗传学杂志

OBJECTIVE@#To carry out genetic testing for a patient with 45,X/46,XY mosaicism and autism spectrum disorder (ASD).@*METHODS@#Peripheral blood samples of the patient and his parents were collected for the extraction of genomic DNA. Trio-based whole exome sequencing and Sanger sequencing were carried out thereafter.@*RESULTS@#The proband and his father were found to harbor a heterozygous c.4781G>A (p.Arg1594Gln) variant of the CACNA1I gene. In addition, the proband was also found to harbor a de novo c.268C>T (p.Arg90Trp) missense variant of the MTRR gene. Based on guidelines of the American College of Medical Genetics and Genomics (ACMG), the c.4781G>A (p.Arg1594Gln) variant of the CACNA1I gene was predicted to be pathogenic (PVS1, PM1, PM2, PP3), while the c.268C>T (p.Arg90Trp) variant of the MTRR gene was predicted to be of uncertain significance.@*CONCLUSION@#Variants of the CACNA1I and MTRR genes, together with the chromosomal mosaicism, may have predisposed to the susceptibility to the ASD in this patient.

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.

Genetic analysis of a fetus with mosaicism of 13q inversion duplication / 中华医学遗传学杂志

OBJECTIVE@#To report on a case of mosaicism 13q inversion duplication, analyze its mechanism, and discuss the correlation between its genotype and phenotype.@*METHODS@#Amniotic fluid and umbilical cord blood were collected at 23 and 32 weeks of gestation, respectively. Combined with G-banding chromosome karyotyping analysis, single nucleotide polymorphism array (SNP-array) and fluorescence in situ hybridization (FISH) were used to confirm the result.@*RESULTS@#The karyotype of the fetus was determined as 47,XY,+inv dup(13)(q14.3q34)/46,XY. After careful counseling, the couple decided to continue with the pregnancy, and had given birth to a boy at 40 weeks' gestation. Except for a red plaque (hemangioma) on the nose bridge, no obvious abnormality (intelligence to be evaluated) was discovered.@*CONCLUSION@#To provide reference for clinical genetic counseling and risk assessment, the location and proportion of new centromere formation should be fully considered in the case of mosaicism 13q inversion duplication.

Analysis of a patient with tuberous sclerosis complex due to mosaicism TSC2 mutation / 中华医学遗传学杂志

OBJECTIVE@#To analyze variants of TSC1 and TSC2 genes in a Chinese patient with tuberous sclerosis complex (TSC).@*METHODS@#Peripheral blood samples were collected from the patient and her parents with informed consent. Following extraction of genomic DNA, potential variants of the TSC1 and TSC2 genes was detected by using targeted capture next-generation sequencing (NGS) and Sanger sequencing.@*RESULTS@#The patient was found to harbor a de novo mosaicism variant c.3295_3298delG (Val1100CysfsTer3) of the TSC2 gene, with the proportion of the mutant allele determined as 13.4%, which was confirmed by Sanger sequencing. Based on the guidelines from the American College of Medical Genetics and Genomics (ACMG), the c.3295_3298delG (Val1100CysfsTer3) variant was predicted to be pathogenic (PVS1+PS2+PM2).@*CONCLUSION@#The mosaicism heterozygous variant of c.3295_3298delG of the TSC2 gene, as detected by both NGS and Sanger sequencing, probably underlay the TSC2 in this patient.

Searching chromosome mosaicisms in 45, X Turner syndrome: how relevant is it?

ABSTRACT Objective: To investigate the presence of chromosome mosaicism, especially for the presence of Y derived material in 45,X women with Turner syndrome (TS). Materials and methods: FISH and PCR were performed for the presence of chromosome mosaicism and Y-derived-material and genetic findings were correlated to clinical data. Results: Thirty-one participants were enrolled: 18 (58%) had chromosome mosaicisms (FISH), Y-derived material was found in 2. Yet, SRY primer was found with PCR in only one of them and DYZ3 was not found. The most frequent clinical findings were short or webbed neck (81,82%), high-arched palate (78%), breast hypertelorism, e cubitus valgus and genu valgus (57.6%, both), short fourth metacarpals (46.9%), epicanthic folds (43.8%), shield chest (43.8%), lymphedema (37.5%), and low set ears (34.4%). Both patients with Y-derived-material had primary amenorrhea, dyslipidemia and reached the height of 150 cm despite not treated with recombinant growth hormone (GHr). One of them showed 26% of leukocytes with Y-derived material and few clinical findings. Conclusions: FISH techniques proved efficient in detecting chromosome mosaicisms and Y-derived material and searching in different tissues such as mouth cells is critical due to the possibility of tissue-specific mosaicism. Phenotypical variance in TS may be a signal of chromosome mosaicisms, especially with the presence of Y-derived material.

Genetic analysis of an individual with a fragile site at 16q22 / 中华医学遗传学杂志

OBJECTIVE@#To analyze a patient with infertility and a fragile site found at 16q22 by using cytogenetic methods.@*METHODS@#Peripheral blood sample was taken from the patient and subjected to chromosomal karyotyping and single nucleotide polymorphism microarray (SNP-array) analysis.@*RESULTS@#The patient was found to be a mosaicism for a fragile site at 16q22, which has a variable morphology and cannot be induced by folic acid treatment. No abnormality was found by SNP-array analysis.@*CONCLUSION@#A rare fragile site, which can be induced without folic acid treatment, has been identified at 16q22. The strategy of assisted reproduction for such individuals is yet to be explored.

Impact of confined placental mosaicism on non-invasive prenatal testing and pregnancy outcomes / 中华医学遗传学杂志

OBJECTIVE@#To assess the impact of confined placental mosaicism (CPM) on non-invasive prenatal testing (NIPT) and pregnancy outcomes.@*METHODS@#Copy number variation sequencing (CNV-seq) and single nucleotide polymorphism array (SNP-array) were carried out on placental specimen sampled from eight pregnancies with confirmed false-positive NIPT results. The impact of CPM on NIPT and pregnancy outcomes were analyzed based on the laboratory tests and clinical characteristics.@*RESULTS@#Five of the eight cases with false-positive NIPT results were proven to be CPM involving trisomy 9, 13, 21, 22, and X, respectively. The mosaic ratios for different placental regions have varied from 4% to 80%. Two fetuses with confirmed CPM showed fetal growth restriction (FGR) and additional ultrasound abnormalities, 1 fetus showed only FGR. The remaining two fetuses showed normal growth.@*CONCLUSION@#NIPT is highly sensitive to CPM, whilst CPM is an important cause for false-positive NIPT result. CPM may be associated with FGR. Investigation of the presence of CPM is important for both pre- and post-test genetic counseling and management of the pregnancy.

Prenatal cytogenetic and molecular genetic analysis of a fetus with confined placenta mosaicism for trisomy 16 / 中华医学遗传学杂志

OBJECTIVE@#To review the clinical data of a fetus with false positive result of non-invasive prenatal testing (NIPT) due to confined placental mosaicism (CPM).@*METHODS@#Amniotic fluid sample was taken from a pregnant women with high risk for chromosome 16 aneuploidy for karyotyping analysis, single nucleotide polymorphism array (SNP array) and interphase fluorescence in situ hybridization (FISH). Genetic testing was also conducted on the fetal and maternal surface of the placenta, root of umbilical cord and fetal skin tissue after induced abortion.@*RESULTS@#Cytogenetic analysis of the amniotic fluid sample yielded a normal karyotype. SNP array revealed mosaicism (20%) of trisomy 16 in the fetus. FISH confirmed the presence of mosaicism (25%) for trisomy 16. After induced labor, all sampled sites of placenta were confirmed to contain trisomy 16 by SNP array, while the analysis of fetal skin tissue yielded a negative result.@*CONCLUSION@#CPM is an important factor for false positive NIPT result. Prenatal identification of CPM and strengthened pregnancy management are important to reduce adverse pregnancy outcomes.

Genetic analysis of a fetus with mosaicism of structural aberration of Y chromosome / 中华医学遗传学杂志

OBJECTIVE@#To carry out genetic analysis and parental tracing for a fetus with an inconclusive chromosomal karyotype.@*METHODS@#The fetus and its parents were subjected to combined chromosomal karyotyping, chromosomal microarray analysis (CMA), fluorescence in situ hybridization (FISH) and multiplex PCR testing for Y chromosome microdeletions.@*RESULTS@#The fetus was found to have a karyotype of 45,X[18]/46,X,+mar[72]. CMA revealed that the fetus has carried a 2.6 Mb duplication at Yp11.32p11.31 and a 44.5 Mb deletion at Yq11.21q12. Interphase FISH of amniocytes confirmed the chromosomal mosaicism in the fetus, which has derived from Y chromosome. Multiplex PCR revealed deletion of AZFb and AZFc regions on the Y chromosome. No karyotypic abnormality was found with either parent at 400-band level.@*CONCLUSION@#Combined genetic analysis has delineated the aberrant karyotype in the fetus, which has facilitated prediction of its clinical phenotype and genetic counseling.

Autism spectrum disorder/development delay in siblings with SCN2A mutations caused by germline mosaicism / 中华医学遗传学杂志

OBJECTIVE@#To report on a family which has two siblings with SCN2A mutation caused by germline mosaicism suffering from autism spectrum disorder/development delay (ASD/DD).@*METHODS@#Clinical data was collected for the proband and his parents. Next generation sequencing (NGS) was carried out on the proband and his parents. Suspected mutations were verified by Sanger sequencing of the proband, his parents and brother. To detect whether there is a low proportion of somatic mosaicism in the parents, a droplet digital PCR was conducted. The result of ddPCR showed that the father was germline mosaicism (0.233%).@*RESULTS@#NGS has identified a de novo splicing mutation of the SCN2A gene, c.605+1G>A, in the proband and his brother. Combined with its clinical phenotype and inheritance pattern, SCN2A was judged to be the pathogenic gene. Above findings strongly suggested parental germline mosaicism.@*CONCLUSION@#ASD/DD in siblings with SCN2A mutations caused by germline mosaicism. Paternal mosaicism should be considered as one of the important inheritance patterns for counseling parents with a child carrying SCN2A mutation. The ddPCR can help to reveal very low proportion of germline mosaicism.

Detección de un mosaico de trisomía 21 en líquido amniótico / Detection of a mosaicism of trisomy 21 in amniotic liquid

Resumen Se analizó un resultado con alteración cromosómica tomado de una base de datos conformada por un total de 4755 muestras de líquido amniótico extraídos mediante amniocentesis con indicación de su médico tratante, riesgo sérico y edad materna avanzada. En este reporte se presenta la detección de un mosaico de trisomía 21 en líquido amniótico, mediante la técnica de Banda G donde se analizaron 20 metafases. Los resultados obtenidos documentan una composición cromosómica 47, XY+21 y 46, XY con una relación 9:11 respecto a las metafases analizadas, confirmándose así el diagnóstico del Síndrome de Down secundario a mosaico.

Abstract A result with chromosomal alteration was analyzed from a database consisting of a total of 4755 samples of amniotic fluid extracted by amniocentesis with indication of the attending physician, serum risk and advanced maternal age. This report presents the detection of a mosaicism of trisomy 21 in amniotic fluid, using G- Banding where 20 metaphases were analyzed. The results obtained document a chromosomal composition 47, XY + 21 and 46, XY with a 9:11 ratio with respect to the metaphases analyzed, confirming the diagnosis of Down syndrome secondary to mosaicism.

High frequency of Y chromosome microdeletions in male infertility patients with 45,X/46, XY mosaicism

The mosaic 45,X/46,XY karyotype is a common sex chromosomal abnormality in infertile men. Males with this mosaic karyotype can benefit from assisted reproductive therapies, but the transmitted abnormalities contain 45,X aneuploidy as well as Y chromosome microdeletions. The aim of this study was to investigate the clinical and genetic characteristics of infertile men diagnosed with 45,X/46,XY mosaicism in China. Of the 734 infertile men found to carry chromosomal abnormalities, 14 patients were carriers of 45,X/46,XY mosaicism or its variants, giving a prevalence of 0.27% (14/5269) and accounting for 1.91% (14/734) of patients with a chromosomal abnormality. There were ten cases (71.43%, 10/14) of 45,X mosaicism exhibiting AZF microdeletions. Case 1 and Case 4 had AZFc deletions, and the other eight cases had AZFb+c deletions. A high frequency of Y chromosome microdeletions were detected in male patients with 45,X/46,XY mosaicism. Preimplantation genetic diagnosis should be offered to men having intracytoplasmic sperm injection for hypospermatogenesis caused by 45,X/46,XY mosaicism, to avoid the risk of transfering AZF microdeletions in addition to X monosomy in male offspring.

Genetic analysis of a mosaic case with low proportion mutation of / 浙江大学学报·医学版

OBJECTIVE@#To perform gene mutation analysis in a patient with atypical clinical manifestations of tuberous sclerosis (TSC) for definite diagnosis.@*METHODS@#Peripheral blood DNA was obtained from a patient with clinically suspected TSC and her parents, and all exons and their flanking sequences of @*RESULTS@#A heterozygous nonsense mutation c.1096G>T (p.E366*) was identified in the exon 11 of the @*CONCLUSIONS@#The somatic mosaic mutation c.1096G>T (p.e366*) may be responsible for the phenotype of TSC in this patient. And the drop digital PCR is expected to be a diagnostic method for somatic cells mosaicism.

Analysis of a female with a peripheral blood lymphocytic karyotype of trisomy 18 but normal intelligence / 中华医学遗传学杂志

OBJECTIVE@#To explore the genetic basis for a female with a peripheral lymphocyte karyotype of trisomy 18 but normal intelligence.@*METHODS@#G-banding karyotype analysis, fluorescence in situ hybridization (FISH) and single nucleotide polymorphism microarray (SNP array) were employed to analyze the peripheral blood sample and buccal cells from the patient.@*RESULTS@#Chromosomal karyotyping, SNP array and FISH analysis of the patient's peripheral blood all suggested 47,XX,+18. Interphase FISH analysis of buccal cells, however, revealed presence of 45,X and low percentage of trisomy 18 and monosomy 18.@*CONCLUSION@#The clinical manifestation of germ layer chromosomal mosaicism is complex. The impact of the genetic disorder on the individual will depend on the structure and function derived from the affected germ layer.

Analysis of a case with gonadal mosaicism for COL1A2 variant / 中华医学遗传学杂志

OBJECTIVE@#To explore the genetic basis for a couple with normal phenotype but repeated pregnancies with fetuses affected by osteogenesis imperfecta.@*METHODS@#Whole exome sequencing (WES) was carried out on fetal specimens and parental DNA to detect potential pathologic variants. Suspected variants were verified by Sanger sequencing. Semen sample of the husband was collected for the extraction of genome DNA, and whole genome amplification (WGA) was performed for single sperms isolated from the sample.@*RESULTS@#WES has identified a heterozygous c.1378G>A (p.G460S) variant of the COL1A2 gene in the fetus, which was predicted to be pathogenic but not detected in peripheral blood samples of both husband and wife. The heterozygotic variant was detected in semen DNA from the husband. Among 15 spermatozoa, 4 were found to harbor the variant.@*CONCLUSION@#The fetus was diagnosed with osteogenesis imperfecta, and the gonadal mosaicism probably accounted for the repeated abnormal pregnancies. Possibility of gonadal mosaicism should be considered when counseling couples with normal phenotype and genotype but recurrent abnormal pregnancies and/or births of children with similar phenotypes and genetic variants.

Prenatal diagnosis of a fetus with Pallister-Killian syndrome with combined cytogenetic and molecular methods / 中华医学遗传学杂志

OBJECTIVE@#To carry out prenatal diagnosis for a fetus with Pallister-killian syndrome (PKS).@*METHODS@#The fetus was found to have limb malformations at 23rd gestational week. With informed consent from its parents, amniotic fluid sample was taken from the fetus and subjected to chromosomal karyotyping, chromosomal microarray analysis (CMA) and fluorescence in situ hybridization (FISH) assay.@*RESULTS@#G-banding analysis suggested the fetus has a mos47,XY,+mar[55]/46,XY[10] karyotype. CMA analysis of the cultured amniocytes with CytoScan 750K microarray revealed a segmental tetrasomy duplication of 12p13.33p11.1. FISH confirmed a 70% mosaicism of tetrasomy 12p in the metaphase amniocytes with 12pter/12qter probes.@*CONCLUSION@#Combined use of G-banding karyotyping, CMA and FISH analysis has enabled diagnosis of PKS in the fetus. Although short limb is a common feature of PKS, unequal femur length has not been reported previously, which has expanded the spectrum of PKS-associated limb abnormalities.

Genetic analysis of a case with ectodermal dysplasia using whole exome sequencing / 中华医学遗传学杂志

OBJECTIVE@#To explore the genetic cause of a patient suspected for congenital ectodermal dysplasia with repeated hyperthermia and to assess the reproductive risk for his family.@*METHODS@#Medical whole-exome sequencing (WES) were used to detect single-nucleotide variations and low-coverage massively parallel copy number variation sequencing (CNV-seq) were employed to verify suspected CNVs. PCR and real-time quantitative PCR were applied to confirm the deletion of EDA gene.@*RESULTS@#The results of WES suggested that the patient carried a hemizygous deletion for chrX:69 243 016-69 395 730. CNV-seq indicated that the patient carried a deletion of approximately 0.12 Mb on Xq13.1, which encompassed the EDA gene. The PCR results confirmed that there was a hemizygous deletion of exons 3 to 8 of the EDA gene. The same deletion was not found in his mother.@*CONCLUSION@#The congenital ectodermal dysplasia of the patient may be attributed to deletion of exons 3 to 8 of the EDA gene, which could be de novo or derive from germline mosaicism of his mother. The WES and CNV-seq are of great value for the diagnosis of rare diseases.

Síndrome de Cri du chat: primer reporte en mosaico en el suroccidente colombiano / Cri du chat syndrome: first report of mosaicism in the colombian southwest

El síndrome de Cri du chat es una alteración cromosómica causada por deleciones en el brazo corto de cromosoma 5, las cuales varían en tamaño, desde muy pequeñas que comprometen solo el locus 5p15.2, hasta la pérdida de todo el brazo corto. Las mutaciones se originan de novo en el 80% a 90% de los casos. Existen dos regiones críticas para el síndrome de Cri du chat; una ubicada en 5p15.3, cuya deleción se manifiesta con el llanto de maullido de gato y retraso en el habla, y otra ubicada en 5p15.2, cuya deleción se manifiesta como microcefalia, hipertelorismo, retraso psicomotor y mental severo. Se han descrito varios genes implicados localizados en estas regiones críticas; entre ellos, TERT, SEMA5A, CTNND2 y MARCHF6, cuya haploinsuficiencia se asocia con los diferentes fenotipos del Cri du chat. En este artículo se describe el caso clínico de una paciente femenina de 8 meses de vida, con características clínicas y un análisis citogenético en mosaico que confirmaron el síndrome de Cri du chat. Este caso es el primero reportado de esta variante en el suroccidente colombiano.

Cri du chat syndrome is a chromosomal disorder caused by deletions in the short arm of chromosome 5, which vary in size, from very small and involving only the 5p15.2 locus, to the loss of the entire short arm. Mutations originate de novo in 80% to 90% of cases. There are two critical regions for Cri du chat syndrome; one located at 5p15.3 with a deletion that is manifested as a cat's cry and speech delay, and another located at 5p15.2 with a deletion that manifests as microcephaly, hypertelorism, severe psychomotor and mental retardation. Several involved genes located in these critical regions have been described; among them, TERT, SEMA5A, CTNND2 and MARCHF6, and whose haploinsufficiency is associated with the different phenotypes of Cri du chat. This article describes the clinical case of an 8-monthold female patient, with clinical characteristics and a mosaic cytogenetic analysis that confirmed Cri du chat syndrome. This case is the first reported of this variant in southwestern Colombia.