Genetic diagnosis of a fetus with Dandy-Walker syndrome / 中华医学遗传学杂志

Objective@#To explore the genetic basis for a fetus with Dandy-Walker malformation.@*Methods@#G-banding chromosomal karotyping, single nucleotide polymorphism microarray (SNP array) and fluorescence in situ hybridization (FISH) were carried out for the fetus. Chromosomal karyotyping and FISH assay were also carried out for both parents.@*Results@#SNP array has detected a 4266 kb microdeletion at 6p25.3p25.1 in the fetus, which was confirmed by FISH. FISH analysis of the parents demonstrated that the father has carried a cryptic t(6; 14)(p25.1; p13) translocation, while the fetus has a der(6)t(6; 14)(p25.1; p13) derived the paternal translocation.@*Conclusion@#The der(6)t(6; 14)(p25.1; p13) probably underlies the Dandy-Walker malformation in the fetus. The 6p25.3p25.1 microdeletion is due to unbalanced gametes produced by the father’s cryptic balanced translocation.

Genetic analysis of a child with Sotos syndrome / 中华医学遗传学杂志

OBJECTIVE@#To explore the genetic basis for a child with mentally retardation.@*METHODS@#G-banding karyotyping, single nucleotide polymorphism array (SNP-array) and fluorescence in situ hybridization (FISH) were performed for the child. Karyotyping and FISH were also carried out for her parents.@*RESULTS@#SNP-array has detected a 5077 kb microdeletion at 5q35.2q35.3 and a 4964 kb microduplication at 7q36.2q36.3 in the child. The results were confirmed by FISH. Based on above results, the father was subsequently found to carry a cryptic t(5;7) (q35.2; q36.2) translocation. The child was verified to have inherited a der(5) t(5;7)(q35.2; q36.2) from her father.@*CONCLUSION@#The 5077 kb microdeletion at 5q35.2q35.3 may have predisposed to the Sotos syndrome in the child. SNP-array combined with G-banding karyotyping and FISH can help to detect cryptic chromosomal translocations among patients.

Genetic diagnosis of a fetus with Dandy-Walker syndrome / 中华医学遗传学杂志

OBJECTIVE@#To explore the genetic basis for a fetus with Dandy-Walker malformation.@*METHODS@#G-banding chromosomal karotyping, single nucleotide polymorphism microarray (SNP array) and fluorescence in situ hybridization (FISH) were carried out for the fetus. Chromosomal karyotyping and FISH assay were also carried out for both parents.@*RESULTS@#SNP array has detected a 4266 kb microdeletion at 6p25.3p25.1 in the fetus, which was confirmed by FISH. FISH analysis of the parents demonstrated that the father has carried a cryptic t(6;14) (p25.1;p13) translocation, while the fetus has a der(6)t(6;14)(p25.1;p13) derived the paternal translocation.@*CONCLUSION@#The der(6)t(6;14)(p25.1;p13) probably underlies the Dandy-Walker malformation in the fetus. The 6p25.3p25.1 microdeletion is due to unbalanced gametes produced by the father's cryptic balanced translocation.

Application of single nucleotide polymorphism microarray in clinical diagnosis of intellectual disability or retardation / 浙江大学学报·医学版

OBJECTIVE@#To assess the clinical application of single nucleotide polymorphism microarray (SNP array) in patients with intellectual disability/developmental delay(ID/DD).@*METHODS@#SNP array was performed to detect genome-wide DNA copy number variants (CNVs) for 145 patients with ID/DD in Women's Hospital, Zhejiang University School of Medicine from January 2013 to June 2018. The CNVs were analyzed by CHAS software and related databases.@*RESULTS@#Among 145 patients, pathogenic chromosomal abnormalities were detected in 32 cases, including 26 cases of pathogenic CNVs and 6 cases of likely pathogenic CNVs. Meanwhile, 18 cases of uncertain clinical significance and 14 cases of likely benign were identified, no significant abnormalities were found in 81 cases (including benign).@*CONCLUSIONS@#SNP array is effective for detecting chromosomal abnormalities in patients with ID/DD with high efficiency and resolution.

Single nucleotide polymorphism microarray in prenatal diagnosis of fetuses with absent nasal bone / 浙江大学学报·医学版

OBJECTIVE@#To assess the clinical application of single nucleotide polymorphism microarray (SNP array) in prenatal genetic diagnosis for fetuses with absent nasal bone.@*METHODS@#Seventy four fetuses with absent nasal bone detected by prenatal ultrasound scanning were recruited from Women's Hospital, Zhejiang University School of Medicine during June 2015 and October 2018. The chromosome karyotypes analysis and SNP array were performed. The correlation between absent fetal nasal bone and chromosome copy number variants was analyzed.@*RESULTS@#Among 74 fetuses, 19 were detected to have chromosomal abnormalities, including 16 cases of trisomy-21, 1 case of trisomy-18 and two cases of micro-deletion/duplication. Among 46 cases with isolated absence of nasal bone, 3 had trisomy-21, and 1 had a micro-duplication. Absence of nasal bone in association with nuchal translucency thickening had a higher rate of abnormal karyotypes compared with isolated absence of nasal bone (=32.27,<0.01).@*CONCLUSIONS@#Fetuses with absent nasal bone and nuchal translucency thickening are likely to have chromosome abnormalities, and SNP array testing is recommended to exclude the chromosome abnormalities.

Genetic analysis of a fetus with multiple malformations caused by complex translocations of four chromosomes / 浙江大学学报·医学版

OBJECTIVE@#To conduct genetic analysis in a fetus with complex translocation of four chromosomes.@*METHODS@#G-banded chromosome karyotype analysis, single nucleotide polymorphism array (SNP array) and fluorescence hybridization (FISH) were performed in a fetus with multiple malformations. Peripheral blood chromosome karyotype and FISH were also carried out for the parents.@*RESULTS@#The fetal amniotic fluid karyotype was 46, XY, t(12; 13)(q22; q32). SNP array analysis showed that there were 20 192 kb duplication at 1q42.13q44 and 13 293 kb deletion at 15q26.1q26.3 in the fetus. The results of karyotype and SNP array were inconsistent. FISH analyses on the parental peripheral blood samples demonstrated that the mother was a cryptic 46, XX, t(1; 15)(q42.1; q26.1) translocation. The fetus had inherited 46, XY, t(12; 13)(q22; q32) from his father and der(15)t(1; 15)(q42.1; q26.1) from his mother.@*CONCLUSIONS@#The 1q42.13q44 duplication and 15q26.1q26.3 deletion may have contributed to the abnormal sonographic features of the fetus. The combination of cytogenetic, SNP array and FISH techniques was beneficial for providing an accurate genetic counseling.

Prenatal diagnosis of a fetus with Phelan-McDermid syndrome / 中华医学遗传学杂志

OBJECTIVE@#To diagnose a fetus with Phelan-McDermid syndrome (PMS) using various techniques.@*METHODS@#Single nucleotide polymorphism array (SNP Array), multiplex ligation-dependent probe amplification (MLPA), fluorescence in situ hybridization (FISH) were applied in conjunction for the prenatal diagnosis of the fetus.@*RESULTS@#SNP Array detected a 4.03 Mb microdeletion at 22q13.31q13.33 in the fetus, which was confirmed by FISH and MLPA. FISH analysis of the parents suggested that the 22q13.31q13.33 deletion has a de novo origin.@*CONCLUSION@#Combined use of various techniques can enable accurate prenatal diagnosis and genetic counseling.

Single nucleotide polymorphism-array in genetic analysis of chorionic villi from early spontaneous miscarriages / 浙江大学学报·医学版

<p><b>OBJECTIVE</b>To assess the clinical application of single nucleotide polymorphism (SNP)-array in detecting abnormal chromosome karyotypes of chorionic villi from early spontaneous abortuses.</p><p><b>METHODS</b>A total of 861 chorionic villus samples from unexplained early spontaneous abortion were collected from Women's Hospital, Zhejiang University School of Medicine during October 2013 and June 2016, and SNP-array was performed to detect genome-wide DNA copy number variants.</p><p><b>RESULTS</b>All samples were successfully tested by SNP-array and 440 cases (51.10%) were found to have abnormal chromosome constitutions. Aneuploidy was identified in 358 (41.58%) cases, distributing in all chromosomes except chromosome 1. Triploidy and haploidy were found in 21 (2.44%) and one case (0.12%), respectively. Thirty-seven cases (4.30%) were identified as single chromosomal segment deletion or duplication, 25 of which were less than 10 Mb in size. For 6 of 25 cases with unclear pathogenesis, family studies were carried out to identify origin of deletion or duplication, showing that 4 cases were de novo and 2 were inherited from one of the parents. Twenty-three cases (2.67%) showed two chromosomal deletion/duplication segments. Combining with karyotyping and fluorescencehybridization, 6 cases were identified as de novo aberration and 11 carried small-size segmental balanced abnormality.</p><p><b>CONCLUSIONS</b>SNP-array can provide a relatively comprehensive genetic analysis of chorionic villi and can detect various kinds of chromosome abnormalities in spontaneous miscarriages.</p>