Prenatal diagnosis and genetic analysis of a rare case with 8p deletion and duplication / 中华医学遗传学杂志

OBJECTIVE@#To explore the genetic etiology for a child featuring mental retardation, language delay and autism.@*METHODS@#G-banding chromosomal karyotyping and single nucleotide polymorphism array (SNP-array) were carried out for the child and her parents.@*RESULTS@#The child was found to have a 46,XX,dup(8p?) karyotype, for which both of her parents were normal. SNP-array revealed that the child has harbored a 6.8 Mb deletion in 8p23.3p23.1 and a 21.8 Mb duplication in 8p23.1p12, both of which were verified as de novo pathogenic copy number variants.@*CONCLUSION@#The clinical features of the child may be attributed to the 8p deletion and duplication. SNP-array can facilitate genetic diagnosis for children featuring mental retardation in conjunct with other developmental anomalies.

Prenatal diagnosis and genetic etiology analysis of a fetus with nemaline myopathy / 中华围产医学杂志

We reported a fetus with limb abnormalities and abnormal ultrasound soft markers diagnosed with nemaline myopathy. A pregnant woman (G1P0) underwent amniocentesis at 18 +2 gestational weeks due to thickened nuchal translucency suggested by ultrasound at 13 +5 gestational weeks. Karyotyping and single nucleotide polymorphism array of the amniotic fluid cells showed no fetal abnormalities. However, ultrasonographic reexaminations at 23, 28, and 28 +1 weeks indicated limb abnormalities and thickened nuchal fold, and the pregnant woman chose to terminate the pregnancy at 29 +2 gestational weeks. Whole exome sequencing showed compound heterozygous mutations of c.602G>A (p.W201*) and c.1516A>C (p.T506P) in the KLHL40 gene inherited from the mother and the father, respectively, resulting in nemaline myopathy type 8.

The value of combined detection of HbA2 and HbF for the screening of thalassemia among individuals of childbearing ages / 中华医学遗传学杂志

OBJECTIVE@#To assess the application value of combined detection of HbA2 and HbF for the screening of thalassemia among a population of childbearing age in Quanzhou, Fujian, and determine the optimal cut-off values for the region.@*METHODS@#Capillary hemoglobin electrophoresis and genetic testing for α and β globin gene mutations were simultaneously carried out on 11 428 patients with suspected thalassemia. Statistical methods were used to analyze the distribution of various types of thalassemia and compare the performance of HbA2 and HbF measurement for the screening of various types of thalassemia. The optimal cut-off values for HbA2 and HbF were determined with the ROC curves.@*RESULTS@#4591 patients with α, β, and αβ compound thalassemia were identified by genetic testing. The most common genotypes for α and β thalassemia included --SEA/αα and β654/βN, β41-42/βN, and β17/βN. The ROC curves were drawn to compare the performance of HbA2 screening for α-, β-, αβ-compound, static α-, mild α-, and intermediate α-thalassemia, and the maximum area under the curves was 0.674, 0.984, 0.936, 0.499, 0.731, 0.956, and the optimal cut-off values for HbA2 were 2.45%, 3.25%, 3.65%, 2.95%, 2.55%, 1.75%, respectively.@*CONCLUSION@#HbA2 is an efficient indicator for identifying intermediate types of α-, β-, and αβ compound thalassemia. The combination of HbA2 and HbF measurement can effectively detect carriers for β-thalassemia mutations.

A case of neonatal Cornelia de Lange syndrome caused by a novel variant of SMC1A gene / 中华医学遗传学杂志

OBJECTIVE@#To explore the genetic etiology of a neonate with suggestive features of Cornelia de Lange Syndrome (CdLS).@*METHODS@#Chromosome karyotyping, copy number variation sequencing (CNV-seq) and whole exome sequencing (WES) were carried out for the child. Meanwhile, peripheral venous blood samples were taken from his parents for verifying the suspected pathogenic variants detected in the child.@*RESULTS@#The child has exhibited developmental delay, microcephaly, ptosis, micrognathia, and low ear setting, and was suspected as CdLS. No abnormality was found by karyotyping and CNV-seq analysis. WES has detected 5 heterogeneous variants and 1 hemizygous variant on the X chromosome. Combining the genetic pattern and result of family verification, a hemizygous C.3500T>C (p.ile1167thr) of the SMC1A gene was predicted to underlay the clinical manifestations of the patient. This variant was not recorded in the dbSNP and gnomAD database. PolyPhen2, Provean, SIFT all predicted the variant to be harmful, and PhastCons conservative prediction is was a conservative mutation. ACMG variant classification standard evidence supports are PM2, PP2, and PP3.@*CONCLUSION@#The novel c.3500T>C (p.Ile1167Thr) missense mutation of the SMC1A gene probably underlay the genetic etiology of CdLS in this child. Above results has enriched the mutation spectrum of CdLS type II, and facilitated clinical counseling for this family.

Non-invasive prenatal testing and genetic diagnosis of a case of Pallister-Killian syndrome / 中华医学遗传学杂志

OBJECTIVE@#To apply combined non-invasive prenatal testing (NIPT), chromosomal karyotyping and chromosomal microarray for the screening and prenatal diagnosis of a fetus with supernumerary small marker chromosome (sSMC).@*METHODS@#Standard NIFTY and full gene NIFTY kits were applied to detect free DNA (cfDNA) isolated from peripheral blood sample of a pregnancy woman. Amniocentesis was carried out for the woman for an abnormal NIPT result. G-banded karyotyping and single nucleotide polymorphism array (SNP array) were used to determine the karyotype and copy number variants in the fetus. The result was validated with a fluorescence in situ hybridization (FISH) assay.@*RESULTS@#Both the standard NIFTY and full gene NIFTY indicated abnormal dup(chr12:707 334-33 308 759), for which the T score value of copy number anomaly in full gene NIFTY is 6.823, which is higher than the standard NIFTY's T-score value of 3.9535. The two NIFTY results were both above the normal threshold ± 3. Conventional G-banding analysis of amniocytes showed that the fetus has a karyotype of 47,XY,+mar. SNP-array delineated duplication of 12p (arr [hg19]12p13.33p11.1 (173 786_34 385 641)× 4, which was verified by FISH. Based on the above results, the fetus was diagnosed as a novel case of Pallister-Killian syndrome.@*CONCLUSION@#NIPT has a certain value for the prenatal detection of PKS. Combined use of multiple techniques can facilitate delineation of the source of sSMC.

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.

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.

Molecular genetic analysis of a child with de novo 16p11.2 microdeletion / 中华医学遗传学杂志

OBJECTIVE@#To explore the genetic basis for a child featuring developmental delay, intelligent disability and language deficit.@*METHODS@#Peripheral blood samples of the child and her parents were collected for routine G-banding karyotyping analysis and single nucleotide polymorphism array (SNP array) detection. Amniotic fluid was also sampled from the mother for karyotyping analysis and SNP array detection.@*RESULTS@#No karyotypic abnormality was found with the child and her parents. SNP array showed that the child has carried a 761.4 kb microdeletion at 16p11.2, while her mother has carried a 444.4 kb microduplication at 15q13.3. Her father's result was negative. Further analysis showed that the 15q13.3 microduplication was inherited from her maternal grandfather who was phenotypically normal. Prenatal diagnosis showed that the fetus has inherited the15q13.3 microduplication from its mother.@*CONCLUSION@#The child has carried a de novo 16p11.2 microdeletion, which overlaps with 16p11.2 microdeletion syndrome region, in addition with similar clinical phenotypes. The 16p11.2 microdeletion probably underlies her abnormal phenotype.

Screening for thalassemia and analysis of gene test results in 41 026 couples of childbearing age in Quanzhou City Fujian Province / 中华地方病学杂志

Objective To investigate the screening and gene test of thalassemia in couples of childbearing age in Quanzhou City Fujian Province.Methods A prospective design was used to collect 41 026 pairs of marriage and excellent blood samples from 12 counties in Quanzhou City,Fujian Province from July 2017 to July 2018.To analyze screened the genetic test results and genotyping of positive thalassemia couples.Firstly,the erythrocyte mean corpuscular volume (MCV) and erythrocyte mean corpuscular hemoglobin (MCH) were used for primary screening.Both sides of the couple were performed hemoglobin electrophoresis when at least one of the couples was screened positive.Couples were performed thalassemia gene detection when blood routine or hemoglobin electrophoresis of the couples was positive.The characteristics of genotypes,homologous carriers and distribution of gene mutations in Quanzhou City were analyzed.Results Among 41 026 couples of childbearing age,4 470 couples had abnormal blood routine examination results in at least one of the couples,the rate of positive screening was 10.90％.There were 952 couples who represented abnormal blood routine or hemoglobin abnormal electrophoresis.Totally 658 cases were diagnosed as thalassemia after thalassemia gene detection,and the diagnosis rate was 34.56％.Totally 493 cases of α-thalassemia were detected,and the higher genotypes were:--SEA/αα,-α3.7/αα and ααQS/αα;and 155 cases of β-thalassemia were detected,and the higher genotypes were:IVS-Ⅱ-654/N,CD41-42/N,CD17/N,βE/N,-28/N;10 cases of α complex β thalassemia were detected.Totally 56 high-risk couples with homologous thalassemia gene were detected,including 50 pairs of homologous α-thalassemia,4 pairs of homologous β-thalassemia,and 2 pairs of homologous couples with α complex β thalassemia.The rate of diagnosis and detection rate of homologous thalassemia in different counties of Quanzhou were quite different (x2 =41.939,21.129,P ＜ 0.05).Among them,the rate of diagnosis in Dehua County was the highest (53.13％,85/160),followed by Yongchun County (39.38％,63/160) and Nan'an City (37.73％,123/326).In addition,the detection rate of homologous thalassemia in Dehua County was the highest (15.00％,12/80),followed by Anxi County (8.44％,13/154) and Yongchun County (7.50％,6/80).Conclusions The incidence of thalassemia in couples of childbearing age in Quanzhou is higher,mainly due to α-thahssemia.The high-risk type of homologous carrier is present in α-thalassemia,which should be paid attention to the prevention and control of thalassemia.

Analysis a family with partial Xq deletion / 中华医学遗传学杂志

<p><b>OBJECTIVE</b>To analyze partial deletion of the long arm of X chromosome in a family and explore the mechanism underlying its phenotypes.</p><p><b>METHODS</b>G-banding technique was employed to analyze the karyotypes of the subjects, and fluorescence in situ hybridization (FISH) was used to analyze their X chromosomes with Xpter, Xqter and WCPX probes.</p><p><b>RESULTS</b>The karyotypes of the proband, her mother and her fetus were all 46,X,del(X)(q24). Combined FISH and karyotyping analysis suggested that the proband and her fetus both carried a Xq24q27.3 deletion.</p><p><b>CONCLUSION</b>The Xq24q27.3 deletion carried by the family is closely related with premature ovarian failure but not with short stature, gonadal dysgenesis and primary amenorrhea.</p>