Genetic analysis of two children with developmental delay and intellectual disability / 中华医学遗传学杂志

OBJECTIVE@#To explore the genetic etiology of two patients with developmental delay and intellectual disability.@*METHODS@#Two children who were respectively admitted to Henan Provincial People's Hospital on August 29, 2021 and August 5, 2019 were selected as the study subjects. Clinical data were collected, and array comparative genomic hybridization (aCGH) was carried out on the children and their parents for the detection of chromosomal microduplication/microdeletions.@*RESULTS@#Patient 1 was a 2-year-and-10-month female and patient 2 was a 3-year-old female. Both children had featured developmental delay, intellectual disability, and abnormal findings on cranial MRI. aCGH revealed that patient 1 has harbored arr[hg19] 6q14.2q15(84621837_90815662)×1, a 6.19 Mb deletion at 6q14.2q15, which encompassed ZNF292, the pathogenic gene for Autosomal dominant intellectual developmental disorder 64. Patient 2 has harbored arr[hg19] 22q13.31q13.33(46294326_51178264)×1, a 4.88 Mb deletion at 22q13.31q13.33 encompassing the SHANK3 gene, haploinsufficiency of which can lead to Phelan-McDermid syndrome. Both deletions were classified as pathogenic CNVs based on the guidelines of American College of Medical Genetics and Genomics (ACMG) and were not found in their parents.@*CONCLUSION@#The 6q14.2q15 deletion and 22q13-31q13.33 deletion probably underlay the developmental delay and intellectual disability in the two children, respectively. Haploinsufficiency of the ZNF292 gene may account for the key clinical features of the 6q14.2q15 deletion.

Advance of research on Phelan-McDermid syndrome / 中华医学遗传学杂志

Phelan-McDermid syndrome (PMS)(OMIM#606232) is a rare genetic disorder caused by a deletion of the distal long arm of chromosome 22q13 involving a variety of clinical features with considerably heterogeneous degrees of severity. This syndrome is characterized by global developmental delay, intellectual disability, hypotonia, absent or severely delayed speech, minor dysmorphic features and autism spectrum disorder. PMS is easy to be misdiagnosed due to the lack of specific clinical manifestations. SHANK3 has been identified as the critical candidate gene for the neurological features of this syndrome. However, some studies have shown that other genes located in the 22q13 region may have a role in the formation of symptoms in individuals with PMS. This article provides a review for recent progress made in research on PMS including etiology, clinical manifestation, diagnosis, and treatment, with a particular emphasis on clinical diagnosis and treatment.

Prenatal ultrasonic characteristics and genetic analysis of fetuses with chromosome 22q11 microdeletion syndrome / 中华医学遗传学杂志

OBJECTIVE@#To analyze the prenatal ultrasonic characteristics and genetic features of 14 fetuses with chromosome 22q11 microdeletion syndrome (22q11DS).@*METHODS@#4989 fetuses were analyzed by using single nucleotide polymorphism array (SNP array) in the Fujian Maternal and Child Health Hospital from November 2016 to November 2019.@*RESULTS@#SNP array showed that 11 fetuses had classic 3 Mb microdeletion in 22q11 region, one fetus had 2.0 Mb microdeletion, and two fetuses had 1.0 Mb microdeletion. The 1.0 Mb microdeletion in 22q11 region contains SNAP29 and CRKL genes, which may increase the risk of congenital renal malformation and cardiovascular malformation.@*CONCLUSION@#Prenatal ultrasonic characteristics of fetuses with 22q11 microdeletion syndrome vary, and SNP array is a powerful tool to diagnose such diseases, which can provide accurate genetic diagnosis and enable prenatal diagnosis.

Phenotypic and genetic analysis of a boy with partial trisomy of 22q / 中华医学遗传学杂志

OBJECTIVE@#To delineate the nature and origin of chromosomal aberration in a boy with mental retardation and multiple congenital deformities.@*METHODS@#Chromosomal karyotypes of the proband and his parents were determined by routine G-banding analysis. Genomic DNA was also analyzed with single nucleotide polymorphism array (SNP array).@*RESULTS@#The karyotype of the proband was 46,X,add(Y)(q11.23). No karyotypic abnormality was detected in either parent. SNP array has identified a de novo 21.6 Mb duplication at 22q12qter in the proband.@*CONCLUSION@#The de novo 22q12qter duplication probably underlies the abnormalities in the proband.

Genetic analysis of an infant with duplication of 22q12.1-q13.3 / 中华医学遗传学杂志

OBJECTIVE@#To explore the genetic basis for an infant with multiple malformations including congenital heart disease and cleft palate.@*METHODS@#The child and his parents were subjected to conventional chromosomal karyotyping and low-coverage massively parallel copy number variation sequencing (CNV-seq) analysis.@*RESULTS@#The infant was found to have a 46,X,add(Y)(q11.23) karyotype, and his CNV-seq result was seq [hg19] 22q12.1q13.3 (29 520 001-51 180 000)× 3. His parents were found to be normal by both methods.@*CONCLUSION@#The additional chromosomal material found on Yq, verified as duplication of 22q12.1-q13.3, may account for the abnormal phenotype in this infant. CNV-seq has provided a useful complement for the diagnosis and more accurate information for genetic counseling.

Prenatal genetic analysis of three fetuses with abnormalities of chromosome 22 / 中华医学遗传学杂志

OBJECTIVE@#To carry out genetic testing for 3 fetuses with abnormal prenatal screening.@*METHODS@#Fetal ultrasound, karyotype analysis, single nucleotide polymorphism (SNP) array and fluorescence in situ hybridization were performed.@*RESULTS@#Abnormalities of chromosome 22 were found with all 3 fetuses. Fetus 1 harbored a 7.1 Mb deletion in 22q13.2q13.33 region, which involved 54 OMIM genes including SHANK3 and FBLN1. Fetus 2 had a mosaicism karyotype, with 12% of cells harboring a 6.6 Mb deletion in 22q13.31q13.33, covering 48 OMIM genes such as SHANK3 and PPARA, and 5% of cells harboring a 26.1 Mb duplication in 22q11.1q13.2 involving 285 OMIM genes. Fetus 3 carried a tandem duplication of 1.7 Mb in 22q11.1q11.21, which involved 10 OMIM genes including CECR1, CECR2 and ATP6V1E1. No abnormality was found in the three couples by chromosomal karyotyping and SNP array analysis.@*CONCLUSION@#The severity of diseases caused by chromosome 22 abnormalities not only depends on the range of the deletion or duplication, but is also closely related to chromosome structure, gene dose and genetic environment. Combined ultrasonography and various genetic testing techniques in prenatal diagnosis can greatly increase the detection rate of genetic diseases with substantial phenotypic variation.

Prenatal diagnosis of a fetus with Phelan-McDermid syndrome and 21q21 microdeletion by multiple genetic techniques / 中华医学遗传学杂志

OBJECTIVE@#To carry out prenatal diagnose for a fetus with ultrasonography abnormalities using multiple genetic techniques.@*METHODS@#Routine G-banding chromosomal analysis and single nucleotide polymorphism array (SNP-array) were applied in conjunction for the prenatal diagnosis of the fetus. The result was confirmed by fluorescence in situ hybridization (FISH).@*RESULTS@#SNP-array detected that the fetus has carried a hemizygous 5.1 Mb deletion at 22q13.31q13.33, which is associated with Phelan-McDermid syndrome, and a hemizygous 4.5 Mb deletion at 21q21.1q21.2. FISH analysis of the fetus and its parents suggested that both deletions were de novo in origin.@*CONCLUSION@#The hemizygous deletions on 21q21.1q21.2 and 22q13.31q13.33 probably underlay the abnormal phenotype of the fetus. Genetic analysis can provide crucial information for the prenatal diagnosis and genetic counseling.

Cardiopatías congénitas asociadas a la microdeleción 22q11. 2, en un hospital pediátrico / Congenital heart defects associated with a 22q11. 2 microdeletion at a pediatric hospital

Introducción: El síndrome de deleción 22q11.2, también llamado síndrome Velo-Cardio-Facial (VCFS/del22q11.2) o síndrome de DiGeorge, es una entidad causada por una anomalía cromosómica, deleción en la región q11.2 (brazo largo) del cromosoma 22. Se trata de una enfermedad multisistémica de expresión variable que afecta el aparato cardiovascular, la inmunidad, las funciones endocrinológicas, la cavidad oral, el desarrollo neurocognitivo, con una expresión facial particular. La prevalencia estimada es de 1:2000/4000. Objetivos: Identificar y describir las cardiopatías congénitas más frecuentemente asociadas a pacientes con síndrome de microdeleción 22q11.2. Materiales y métodos: Estudio descriptivo, transversal y retrospectivo que analiza los pacientes con diagnóstico de microdeleción 22q11.2 atendidos en el Hospital Garrahan desde Octubre de 1998 hasta Febrero 2018. El criterio diagnóstico fueron signos clínicos compatibles y la presencia de la microdeleción 22q11.2 por técnica de FISH o MLPA. Resultados: Población: 321 pacientes, 151 Femeninos (47%) 170 Masculinos (53%). Rango etario: 0 a 197 meses (1 día a 16,4 años). Mediana de edad al diagnóstico clínico: 31 meses. El 74,4% (239/321) de los pacientes evaluados con microdeleción 22q11.2 tuvieron cardiopatías congénitas asociadas a facies peculiar. Las cardiopatías congénitas más frecuentemente asociadas fueron conotroncales. De los pacientes con cardiopatías congénitas el 68,6% requirió cirugía cardiovascular. Fallecieron 24 pacientes (10%) con cardiopatías congénitas asociadas y en el 93% la causa de muerte estuvo relacionada a la afección cardiológica. Conclusiones: Los pacientes con microdeleción 22q11.2 se asocian con un alto porcentaje de cardiopatías congénitas, la gran mayoría son complejas (conotroncales) y requieren resolución quirúrgica en los primeros años de vida. Es de vital importancia la evaluación multidisciplinaria de este grupo especial de pacientes con cardiopatía asociada a otras alteraciones extra cardíacas para el diagnóstico precoz y tratamiento oportuno (AU)

Introduction: 22q11.2 deletion syndrome, also called velocardiofacial syndrome (VCFS/del22q11.2) or DiGeorge syndrome, is a condition caused by chromosomal abnormality, a deletion in the q11.2 region (long arm) of chromosome 22. VCFS is a multisystem disease of variable expression that affects the cardiovascular, immune, and endocrine systems, the oral cavity, neurocognitive development, and is associated with specific facial features. The estimated prevalence is 1:2000/4000. Objectives: To identify and describe the most common congenital heart defects associated with 22q11.2 micro-deletion syndrome. Materials and methods: Descriptive, cross-sectional, and retrospective study analyzing patients diagnosed with a 22q11.2 microdeletion seen at Garrahan Hospital from October 1998 to February 2018. Diagnostic criteria were compatible clinical signs and the presence of a 22q11.2 microdeletion identified by FISH or MLPA. Results: Population: 321 patients, 151 female (47%) and 170 Male (53%). Age range: 0 to 197 months (1 day to 16.4 years). Median age at clinical diagnosis: 31 months. Overall, 74.4% (239/321) of patients with a 22q11.2 microdeletion had congenital heart defects associated with a peculiar facies. The most commonly associated congenital heart defects were conotruncal. Of the patients with congenital heart defects, 68.6% required cardiovascular surgery. Of the patients with congenital heart defects 24 patients died (10%) and in 93% the cause of death was related to the heart disease (p 0.002). Conclusions: A high percentage of patients with a 22q11.2 microdeletion have congenital heart defects, which are complex (conotruncal) in the majority, requiring surgical treatment in the first years of life. Multidisciplinary evaluation of this special group of patients with heart defects associated with other extracardiac disorders is essential for an early diagnosis and timely treatment (AU)

Prenatal diagnosis and clinical analysis of two fetuses with Cat-eye syndrome / 中华医学遗传学杂志

OBJECTIVE@#To determine the origin of supernumerary small marker chromosomes (sSMCs) carried by two fetuses.@*METHODS@#Single nucleotide polymorphism array (SNP-array) and fluorescence in situ hybridization (FISH) analysis were carried out on cells cultured from the amniotic fluid samples.@*RESULTS@#SNP-array analysis showed both fetuses to be arr[hg19]22q11.1q11.21(16 888 899-18 649 190)×4, with a duplicated 1.7 Mb region (16 888 899-18 649 190) leading to partial tetrasomy of 22q11.1-22q11.21. FISH confirmed that both fetuses were 47,XN,+mar.ish idic(22)(q11.2) (RP11-958H20 ++),which suggested a diagnosis of Cat-eye syndrome (CES). The appearance of abortuses were consistent with the diagnosis of CES.@*CONCLUSION@#Two fetuses with CES were diagnosed by genetic testing. The latter has provided a basis for 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.

Molecular cytogenetic characterization of five patients with myeloid leukemia and t(12;22)(p13;q12) / 中华医学遗传学杂志

OBJECTIVE@#To explore the clinical and laboratory characteristics of 5 patients with myeloid leukemia and t(12;22)(p13;q12).@*METHODS@#Bone marrow cells were cultured for 24 h and analyzed by standard R-banding. Rearrangement of the MN1 gene was detected by fluorescence in situ hybridization (FISH) using dual color break-apart MN1 probes. MN1-ETV6 and ETV6-MN1 fusion genes were detected by reverse transcription polymerase chain reaction (RT-PCR). And the products were subjected to direct sequencing.@*RESULTS@#Among the 5 patients, 2 had AML-M0, 2 had AML-M4, and 1 had CMML at the initial diagnosis. t(12;22)(p13;q12) was the primary abnormality among all patients. Rearrangements of MN1 gene were detected by FISH in all patients. MN1-ETV6 and ETV6-MN1 fusion genes were detected respectively in 4 and 3 patients.@*CONCLUSION@#t(12;22)(p13;q12) is a rare but recurrent chromosomal abnormality in myeloid leukemia, and is related to poor prognosis. allo-SCT is valuable for patients with t(12;22)(p13;q12).

Analysis of a girl with Phelan-McDermid syndrome / 中华医学遗传学杂志

OBJECTIVE@#To explore the value of single nucleotide polymorphism (SNP) array for molecular diagnosis.@*METHODS@#A Chinese girl suspected for Phelan-McDermid syndrome was subjected to routine G-banding chromosomal analysis, SNP array, and fluorescence in situ hybridization (FISH) assaying.@*RESULTS@#G-banding karyotype analysis has found no abnormality in the girl and her parents. SNP array detected a heterozygous 2.1 Mb deletion at 22q13.33 in the girl, which was confirmed by FISH. The same deletion was not found in either parent. FISH analysis found that her father has carried a balance t(4;22) translocation.@*CONCLUSION@#SNP-array has the advantage of high resolution and accuracy, which is valuable for the diagnosis of microdeletion or microduplication syndromes.

Prenatal diagnosis and pregnancy outcomes of 22q11.2 duplication syndrome: analysis of 8 cases / 浙江大学学报·医学版

OBJECTIVE@#To investigate the relationship between 22q11.2 duplication and clinical phenotype.@*METHODS@#Eight fetuses with 22q11.2 duplication syndrome diagnosed by chromosome microarray analysis (CMA) through amniocentesis from February 2015 to March 2017 were enrolled in the study. The prenatal diagnostic indications, fetal ultrasound, chromosome karyotype, peripheral blood CMA results of parents, pregnancy outcomes and follow-up of postnatal growth and development were retrospectively analyzed.@*RESULTS@#Prenatal serological screening indicated 6 cases with high risk of trisomy 21, 1 case with nuchal fold (NF) thickening and 1 case of maternal chromosomal balanced translocation. Fetal ultrasonography showed 1 case of NF thickening, 1 case of fetal cerebral ventriculomegaly and 6 cases with normal ultrasound. CMA demonstrated that the size of duplication was between 651 kb and 3.26 Mb, and 22q11.2 duplication. Parents' CMA results revealed that 6 cases inherited from one of the parents with normal phenotype, and the parents of 2 cases refused the CMA test. Two couples chose induced labor; 6 cases of continued pregnancy had normal phenotypes at birth. All 6 cases were followed up with longest of 3.5 years. The growth and psychological development were normal in 5 cases, and one case was growth retardation.@*CONCLUSIONS@#There were no specific clinical phenotypes in 22q11.2 duplication syndrome, and most of them were inherited from one parent who has normal phenotype.

Cytogenetic and molecular genetic analysis of the amniotic fluid cells of a fetus with pseudodicentric isochromosome 22 resulting in partial tetraploidy of 22q / 中华医学遗传学杂志

<p><b>OBJECTIVE</b>To diagnose chromosomal abnormalities in amniotic fluid cells by combining karyotyping and single nucleotide polymorphism array (SNP-array) analysis, and to explore the application of SNP-array in routine clinical practice.</p><p><b>METHODS</b>Conventional G banding was used to karyotype a fetal amniotic fluid sample and the corresponding peripheral blood samples from the parents, followed by SNP-array analysis of the fetal genomic DNA from the amniotic fluid.</p><p><b>RESULTS</b>The karyotype of the amniocytes was 47, XX, +mar. The marker chromosome was further identified as psu idic (22) (q11.2) by SNP-array analysis, revealing tetraploidy of a 1.7 Mb fragment in 22q11.1-q11.2 interval that involves the critical region for Cat eye syndrome.</p><p><b>CONCLUSION</b>A rare chromosomal abnormality was identified by combining conventional G banding and SNP-array. The high resolution SNP-array could provide more detailed information for determining the origin of chromosomal abnormalities.</p>

Genomic imbalances in syndromic congenital heart disease / Desequilíbrios genômicos na cardiopatia congênita sindrômica

Abstract Objective: To identify pathogenic genomic imbalances in patients presenting congenital heart disease (CHD) with extra cardiac anomalies and exclusion of 22q11.2 deletion syndrome (22q11.2 DS). Methods: 78 patients negative for the 22q11.2 deletion, previously screened by fluorescence in situ hybridization (FISH) and/or multiplex ligation probe amplification (MLPA) were tested by chromosomal microarray analysis (CMA). Results: Clinically significant copy number variations (CNVs ≥300 kb) were identified in 10% (8/78) of cases. In addition, potentially relevant CNVs were detected in two cases (993 kb duplication in 15q21.1 and 706 kb duplication in 2p22.3). Genes inside the CNV regions found in this study, such as IRX4, BMPR1A, SORBS2, ID2, ROCK2, E2F6, GATA4, SOX7, SEMAD6D, FBN1, and LTPB1 are known to participate in cardiac development and could be candidate genes for CHD. Conclusion: These data showed that patients presenting CHD with extra cardiac anomalies and exclusion of 22q11.2 DS should be investigated by CMA. The present study emphasizes the possible role of CNVs in CHD.

Resumo Objetivo: Identificar desequilíbrios genômicos patogênicos em pacientes que apresentam cardiopatias congênitas (CC) e anomalias extracardíacas e exclusão da síndrome de deleção 22q11.2 (SD22q11.2). Métodos: Foram avaliados por microarray cromossômico (CMA) 78 pacientes negativos para a deleção 22q11.2, previamente testados por hibridação in situ com fluorescência (FISH) e/ou amplificação de múltiplas sondas dependentes de ligação (MLPA). Resultados: Foram identificadas variações do número de cópias de DNA (CNVs) clinicamente significativas (≥ 300 kb) em 10% (8/78) dos casos, além de CNVs potencialmente relevantes em dois casos (duplicação de 993 kb em 15q21.1 e duplicação de 706 kb em 2p22.3). Genes envolvidos como IRX4, BMPR1A, SORBS2, ID2, ROCK2, E2F6, GATA4, SOX7, SEMAD6D, FBN1 e LTPB1 são conhecidos por atuar no desenvolvimento cardíaco e podem ser genes candidatos a CC. Conclusão: Esses dados mostram que pacientes que apresentam CC, com anomalias extracardíacas e exclusão da SD22q11.2, devem ser investigados por CMA. Ainda, este estudo enfatiza a possível função das CNVs nas CC.

Prenatal diagnosis of 22q11 microdeletion syndrome / 中华医学遗传学杂志

<p><b>OBJECTIVE</b>To establish a method for the prenatal diagnosis of 22q11 microdeletion syndrome.</p><p><b>METHODS</b>BACs-on-Beads (BoBs) and fluorescence in situ hybridization (FISH) were performed on a fetus for whom amniotic chromosomal culturing has failed and a pair of twin fetuses suspected for 22q11 deletion syndrome.</p><p><b>RESULTS</b>22q11 microdeletion was detected in all 3 fetuses by prenatal BoBs as well as FISH, with only one red signal detected at the DiGeorge/VCFS N25 site and two green signals on the 22q13.3 ARSA site.</p><p><b>CONCLUSION</b>The combination of prenatal BoBs and FISH can provide a method for the prenatal diagnosis of 22q11 microdeletion.</p>

Phenotypic and genotypic analysis of a fetus carrying an intermediate 22q11.2 deletion encompassing the CRKL gene / 中华医学遗传学杂志

<p><b>OBJECTIVE</b>To delineate the phenotypic characteristics of 22q11.2 deletion syndrome and the role of CRKL gene in the pathogenesis of cardiac abnormalities.</p><p><b>METHODS</b>G-banded karyotyping, single nucleotide polymorphism (SNP) array and fluorescence in situ hybridization (FISH) were performed on a fetus with tetralogy of Fallot detected by ultrasound. Correlation between the genotype and phenotype was explored after precise mapping of the breakpoints on chromosome 22q11.2. SNP array was also performed on peripheral blood samples from both parents to clarify its origin.</p><p><b>RESULTS</b>The fetus showed a normal karyotype of 46,XY. SNP array performed on fetal blood sample revealed a 749 kb deletion (chr22: 20 716 876-21 465 659) at 22q11.21, which encompassed the CRKL gene but not TBX1, HIRA, COMT and MAPK1. Precise mapping of the breakpoints suggested that the deleted region has overlapped with that of central 22q11.2 deletion syndrome. SNP array analysis of the parental blood samples suggested that the 22q11.21 deletion has a de novo origin. The presence of 22q11.21 deletion in the fetus was also confirmed by FISH analysis.</p><p><b>CONCLUSION</b>Central 22q11.21 deletion probably accounts for the cardiac abnormalities in the fetus, for which the CRKL gene should be considered as an important candidate.</p>

Prenatal diagnosis of the isodicentric chromosome 22 associated with cat eye syndrome by multiplex ligation-dependent probe amplification

Cat eye syndrome (CES) is a very rare chromosomal syndrome characterized by various malformations such as anal atresia, preauricular malformation, coloboma of the iris, and congenial heart and renal defects. This genetic disorder is caused by partial duplication of chromosome 22, mostly as a result of a supernumerary isodicentric marker chromosome idic(22)(q11.2). Various congenital abnormalities and extreme phenotypic variability in CES patients have been reported, which have made prenatal diagnosis of CES difficult. We report the first case diagnosed with CES prenatally by multiplex ligation-dependent probe amplification in a woman who was referred to our hospital, for a fetus presenting with heart anomaly.

Genetic diagnosis and follow up of a fetus with Emanuel syndrome / 中华医学遗传学杂志

<p><b>OBJECTIVE</b>To carry out genetic analysis for a fetus with Dandy-Walker malformation and provide prenatal diagnosis for its parents during the subsequent pregnancy.</p><p><b>METHODS</b>Routine G-banding was carried out to analyze the karyotype of the fetus and its parents, and next-generation sequencing (NGS) and fluorescence in situ hybridization (FISH) were used to verify the result.</p><p><b>RESULTS</b>The father showed a normal karyotype, while the mother was found to carry a balanced t(11; 22) (q23; q11) translocation. NGS and FISH analysis verified that the supernumerary marker chromosome carried by the fetus was der(22) t(11; 22) (q23;q11). The fetus was diagnosed with Emanuel syndrome. During the next pregnancy, the fetus was found to carry the same balanced translocation as its mother. After genetic counseling, the couple decided to continue with the pregnancy, and eventually delivered a healthy baby.</p><p><b>CONCLUSION</b>A fetal case of Emanuel syndrome has been identified. The derivative der(22) t(11; 22)(q23; q11) chromosome probably underlies the Dandy-Walker malformation in the fetus. Combined cytogenetic and molecular analyses can attain a more precise diagnosis for fetal abnormalities detected by ultrasonography.</p>

Clinical and molecular cytogenetic analysis of a family with mental retardation caused by an unbalanced translocation involving chromosomes 3 and 22 / 中华医学遗传学杂志

<p><b>OBJECTIVE</b>To explore the genetic cause of a Chinese boy with unexplained mental retardation, and analyze the pattern of inheritance for his family.</p><p><b>METHODS</b>Routine karyotyping, chromosomal microarray analysis (CMA), and fluorescence in situ hybridization (FISH) were used to detect chromosome abnormalities in the patient and his families.</p><p><b>RESULTS</b>Chromosome analysis suggested that the proband and 7 affected individuals had an identical karyotype 46,XN,der(22)t(3;22)(q28;q13)pat, while his father and 5 other relatives carried a same karyotype of 46,XN,t(3;22)(q28;q13). His mother and other family members were normal. CMA analysis confirmed that the patient had a 9.0 Mb duplication at 3q28q29, in addition with a 1.7 Mb deletion at 22q13.3. Above results were confirmed by FISH.</p><p><b>CONCLUSION</b>The abnormal phenotypes of the proband and his family members from five generations have conformed to those of 3q duplication and 22q13.3 deletion caused by unbalanced translocation involving chromosomes 3q and 22q. The presence of multiple patients in this family may be attributed to abnormal gametes produced by parental balanced translocations involving 3q and 22q.</p>