Partial Monosomy 21q Due to De Novo t(15;21)(q26.3;q22.11): A Case Report with Clinical and Molecular Findings

Application of Multicolor Banding for Identification of Complex Chromosome 18 Rearrangements

A systematic analysis of small supernumerary marker chromosomes using array CGH exposes unexpected complexity

Bi-allelic Variants in IQSEC1 Cause Intellectual Disability, Developmental Delay, and Short Stature

We report on two mentally retarded adults with an unbalanced karyotype resulting from a familial balanced translocation between chromosomes 8 and 21, t(8;21)(p21.1;q22.3). This translocation has not been reported before....

22q11.2 Distal Deletion: A Recurrent Genomic Disorder Distinct from DiGeorge Syndrome and Velocardiofacial Syndrome

Complex Inheritance Pattern Resembling Autosomal Recessive Inheritance Involving a Microdeletion in Thrombocytopenia–Absent Radius Syndrome

BackgroundChromosomal microarray analysis has been shown to be a valuable and cost effective assay for elucidating copy number variants (CNVs) in children with intellectual disability and developmental delay (ID/DD).MethodsIn our study, we performed array-based comparative genomic hybridization (array-CGH) analysis using oligonucleotide-based platforms in 542 Czech patients with ID/DD, autism spectrum disorders and multiple congenital abnormalities. Prior to the array-CGH analysis, all the patients were first examined karyotypically using G-banding. The presence of CNVs and their putative derivation was confirmed using fluorescence in situ hybridization (FISH), multiplex ligation-dependent probe amplification (MLPA) and predominantly relative quantitative polymerase chain reaction (qPCR).ResultsIn total, 5.9% (32/542) patients were positive for karyotypic abnormalities. Pathogenic/likely pathogenic CNVs were identified in 17.7% of them (96/542), variants of uncertain significance (VOUS) were detected in 4.8% (26/542) and likely benign CNVs in 9.2% of cases (50/542). We identified 6.6% (36/542) patients with known recurrent microdeletion (24 cases) and microduplication (12 cases) syndromes, as well as 4.8% (26/542) patients with non-recurrent rare microdeletions (21 cases) and microduplications (5 cases). In the group of patients with submicroscopic pathogenic/likely pathogenic CNVs (13.3%; 68/510) we identified 91.2% (62/68) patients with one CNV, 5.9% (4/68) patients with two likely independent CNVs and 2.9% (2/68) patients with two CNVs resulting from cryptic unbalanced translocations. Of all detected CNVs, 21% (31/147) had a de novo origin, 51% (75/147) were inherited and 28% (41/147) of unknown origin.In our cohort pathogenic/likely pathogenic microdeletions were more frequent than microduplications (69%; 51/74 vs. 31%; 23/74) ranging in size from 0.395 Mb to 10.676 Mb (microdeletions) and 0.544 Mb to 8.156 Mb (microduplications), but their sizes were not significantly different (P = 0.83). The pathogenic/likely pathogenic CNVs (median 2.663 Mb) were significantly larger than benign CNVs (median 0.394 Mb) (P < 0.00001) and likewise the pathogenic/likely pathogenic CNVs (median 2.663 Mb) were significantly larger in size than VOUS (median 0.469 Mb) (P < 0.00001).ConclusionsOur results confirm the benefit of array-CGH in the current clinical genetic diagnostics leading to identification of the genetic cause of ID/DD in affected children.

Objective: To evaluate the application of single nucleotide polymorphism (SNP)-microarray and target gene sequencing technology in the clinical molecular genetic diagnosis of unexplained intellectual disability(ID) or developmental delay (DD). Method: Patients with ID or DD were recruited in the Department of Neurology, Affiliated Children's Hospital of Capital Institute of Pediatrics between September 2015 and February 2016. The intellectual assessment of the patients was performed using 0-6-year-old pediatric examination table of neuropsychological development or Wechsler intelligence scale (>6 years). Patients with a DQ less than 49 or IQ less than 51 were included in this study. The patients were scanned by SNP-array for detection of genomic copy number variations (CNV), and the revealed genomic imbalance was confirmed by quantitative real time-PCR. Candidate gene mutation screening was carried out by target gene sequencing technology.Causal mutations or likely pathogenic variants were verified by polymerase chain reaction and direct sequencing. Result: There were 15 children with ID or DD enrolled, 9 males and 6 females. The age of these patients was 7 months-16 years and 9 months. SNP-array revealed that two of the 15 patients had genomic CNV. Both CNV were de novo micro deletions, one involved 11q24.1q25 and the other micro deletion located on 21q22.2q22.3. Both micro deletions were proved to have a clinical significance due to their association with ID, brain DD, unusual faces etc. by querying Decipher database. Thirteen patients with negative findings in SNP-array were consequently examined with target gene sequencing technology, genotype-phenotype correlation analysis and genetic analysis. Five patients were diagnosed with monogenic disorder, two were diagnosed with suspected genetic disorder and six were still negative. Conclusion: Sequential use of SNP-array and target gene sequencing technology can significantly increase the molecular genetic etiologic diagnosis rate of the patients with unexplained ID or DD. Combined use of these technologies can serve as a useful examinational method in assisting differential diagnosis of children with unexplained ID or DD.

Specific copy number variants (CNVs) have been robustly associated with intellectual disability, autism, and schizophrenia. Most of the literature focus has been on documenting the existence of these phenomena. There are few data to guide therapeutic choices for these “orphan” diseases. We call for systematic and longitudinal case reports which, if carefully conducted, may provide crucial initial knowledge to guide therapeutics. We provide a step-by-step overview, a tailored set of consensus criteria for high-quality case reports, and a specific set of learning resources.

We report on a familial three way translocation involving chromosomes 3, 6, and 15 identified by prometaphase banding and fluorescence in situ hybridisation (FISH). Two mentally retarded sibs with different...

Targeted Array CGH

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BackgroundSmall Supernumerary Marker Chromosomes (sSMC) are rare chromosomal abnormalities, which have abnormal banding arrangement and take many shapes. Several disorders have been correlated with sSMC presence. The aim of this study is to characterize the sSMC derived from chromosome 18 by Fluorescence in situ hybridization (FISH) and Array Comparative Genomic Hybridization (aCGH).ResultsNine children with dysmorphic features have been investigated. They have these features in common: a triangular face, low-set ears, a large mouth with a thin upper lip, and a horizontal palpebral fissure. Epicanthus and strabismus were present in two patients. In addition, we have noticed microcephaly and mental and/or developmental delay with low birth weight. However, two patients had standard birth weight; one patient had hypospadias; two had skin problems; and three showed different congenital heart defects. One patient had corpus callosum hypoplasia. Systematic karyotype analysis revealed a de novo supernumerary chromosome. Array CGH showed a gain in copy number on the short arm of chromosome 18 in the nine cases. In one case, the sSMC seemed to be in mosaic. The breakpoints of the marker were identified using aCGH and FISH. Thus, the sSMC led to 18p tetrasomy with approximately 14 Mb lengths, between 364344 and 14763575 based on the human genome version 18.ConclusionsThese results have been completed by FISH in order to ascertain the shape of the sSMC. Our results confirm the uniqueness and particularity of the iso18p syndrome on the phenotypic as well as on the genetic level.

BackgroundKBG syndrome (MIM #148050) is a rare genetic disease, showing an autosomal dominant pattern of inheritance. It was first described by Herrmann et al. in 1975 in three affected families, whose initial letters gave origin to the acronym. A peculiar facies including triangular face, synophrys, macrodontia of the upper central incisors, as well as short stature, skeletal defects and neurodevelopmental disorders (developmental delay, intellectual disability, epilepsy) are the main features of the syndrome. Mutations of the ankirin repeat domain 11 gene (ANKRD11), which harbors at chromosome 16q24.3, have been associated to the syndrome. The encoded protein inhibits ligand-dependent activation of transcription. Due to the growing number of detected ANKRD11 variants associated to phenotypes with various degree of severity, the precise definition of the clinical and genomic profiles of patients is important, also in the perspective of a better understanding of the molecular bases of the disease, genotype-phenotype correlation, and management of affected subjects.Cases presentationWe report on three unrelated patients, observed in as many different Italian (Sicily, Veneto and Friuli-Venezia-Giulia regions) Pediatric Neurology and Medical Genetics outpatient services, showing variously present typical dysmorphic features (e.g., triangular face, macrodontia of upper incisors, brachydactyly), growth retardation and impaired neurodevelopmental profiles (i.e. developmental delay, EEG abnormalities/epilepsy) compatible with KBG syndrome diagnosis. In Patient 1, next generation sequencing analysis of a panel of genes involved in developmental delay and autism spectrum disorders detected two mutations, a pathogenic heterozygous frameshift variant of the ANKRD11 gene (already described in the literature), and a heterozygous missense one in EHMT1 (previously reported as well, and associated with Kleefstra syndrome); in Patient 2, array comparative genomic hybridization (a-CGH) analysis identified a 634 Kb 16q24.3-24.3 deletion involving several genes (CDT1, APRT, GALNS, TRAPPC2L, ACSF3, CDH15), besides ANKRD11, some of which are related with developmental disorders. Finally in Patient 3, Sanger sequencing of the ANKRD11 gene, performed due to the specific diagnostic suspicion raised for precocious teething observed at age 3 months, evidenced an intragenic deletion allowing thus an early diagnosis of disease.ConclusionsWe underline similarities and differences among our patients, and their specific genetic and clinical features, in addition to the variable diagnostic tests used for the diagnosis, reached at different developmental age, i.e. infancy, childhood and adolescence. Pediatricians must be aware of KBG syndrome and should be able, as well, to raise the diagnostic suspicion, especially in the presence of peculiar dysmorphic features, short stature, developmental delay, intellectual disability and epilepsy. Prompt diagnosis may allow to better address any associated emerging neuropsychological and behavioral issues improving the quality of life of the patient and the whole family.

Interstitial deletions in the terminal region of chromosome 6 are rare. We describe three new cases with subtle interstitial deletions in the q24-q26 region of the long arm of chromosome 6. The karyotypes were analyzed at a 550 band level. Patient1 is a 9-month-old boy with an interstitial deletion, del(6)(q24.2q25.1), developmental delay, low birth weight, hypotonia, heart murmur, respiratory distress, craniofacial and genital anomalies. This is the first report of a case with deletion del(6)(q24.2q25.1). Patient 2 is a 17-year-old young man with an interstitial deletion del(6)(q25.1q25.3), developmental delay, short stature, mental retardation, autism, head, face, chest, hand and feet anomalies and a history of seizures. For the first time autism was described as a manifestation in 6q deletions. Patient 3 is baby boy with a de novo interstitial deletion, del(6)(q25.1q26), anomalies of the brain, genital organs, limbs and feet. This is the first report of a case with deletion, del(6)(q25.1q26). In all three patients, fluorescence in situ hybridization (FISH) using chromosome 6 painting probe ruled out an insertion. The ESR (6q25.1) and TBP (6q27) probes were used to confirm the breakpoints. Since TBP signal is present in all cases, it confirmed an interstitial deletion proximal to this probe. Patient 1 has a deletion of the ESR locus; Patient 2 and 3 have signals for the ESR locus on both chromosomes 6. Therefore the deletion in Patients 2 and 3 are between ESR and TBP loci distal to that of Patient 1. FISH validated the deletion breakpoints assessed by conventional cytogenetics. Am. J. Med. Genet. 87:17–22, 1999. © 1999 Wiley-Liss, Inc.