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Mammalian chromosomes are comprised of complex chromatin architecture with the specific assembly and configuration of each chromosome influencing gene expression and function in yet undefined ways by varying degrees of heterochromatinization that result in Giemsa (G) negative euchromatic (light) bands and G-positive heterochromatic (dark) bands. We carried out morphometric measurements of high-resolution chromosome ideograms for the first time to characterize the total euchromatic and heterochromatic chromosome band length, distribution and localization of 20,145 known protein-coding genes, 790 recognized autism spectrum disorder (ASD) genes and 365 obesity genes. The individual lengths of G-negative euchromatin and G-positive heterochromatin chromosome bands were measured in millimeters and recorded from scaled and stacked digital images of 850-band high-resolution ideograms supplied by the International Society of Chromosome Nomenclature (ISCN) 2013. Our overall measurements followed established banding patterns based on chromosome size. G-negative euchromatic band regions contained 60% of protein-coding genes while the remaining 40% were distributed across the four heterochromatic dark band sub-types. ASD genes were disproportionately overrepresented in the darker heterochromatic sub-bands, while the obesity gene distribution pattern did not significantly differ from protein-coding genes. Our study supports recent trends implicating genes located in heterochromatin regions playing a role in biological processes including neurodevelopment and function, specifically genes associated with ASD.

BackgroundPrader-Willi syndrome (PWS) is an imprinting disorder caused by the absence of paternal expressed genes in the Prader-Willi critical region (PWCR) on chromosome 15q11.2-q13. Three molecular mechanisms have been known to cause PWS, including a deletion in the PWCR, uniparental disomy 15 and imprinting defects.ResultsWe report the first case of PWS associated with a single-nucleotide SNRPN variant in a 10-year-old girl presenting with clinical features consistent with PWS, including infantile hypotonia and feeding difficulty, developmental delay with cognitive impairment, excessive eating with central obesity, sleep disturbances, skin picking and related behaviour issues. Whole-exome sequencing revealed a de novo mosaic nonsense variant of the SNRPN gene (c.73C>T, p.R25X) in 10% of DNA isolated from buccal cells and 19% of DNA from patient-derived lymphoblast cells. DNA methylation study did not detect an abnormal methylation pattern in the SNRPN locus. Parental origin studies showed a paternal source of an intronic single-nucleotide polymorphism within the locus in proximity to the SNRPN variant.ConclusionsThis is the first report that provides evidence of a de novo point mutation of paternal origin in SNRPN as a new disease-causing mechanism for PWS. This finding suggests that gene sequencing should be considered as part of the diagnostic workup in patients with clinical suspicion of PWS.

Prader-Willi syndrome (PWS) is a genomic imprinting disorder characterized by infantile hypotonia with a poor suck and failure to thrive, hypogenitalism/hypogonadism, behavior and cognitive problems, hormone deficiencies, hyperphagia, and obesity. The Stanford Binet and Wechsler (WAIS-R; WISC-III) intelligence (IQ) tests were administered on 103 individuals with PWS from two separate cohorts [University of California, Irvine (UCI) (N = 56) and Vanderbilt University (N = 47)] and clinical information obtained including growth hormone (GH) treatment, PWS molecular classes, weight and height. Significantly higher IQ scores (p

Prader-Willi syndrome (PWS) is generally due to sporadic paternal deletions of the chromosome 15q11-q13 region followed by maternal disomy 15. Advanced maternal age is more commonly seen in those with maternal disomy 15. Environmental factors (e.g., drug use, occupational chemical exposure, infectious agents, and irradiation) could account for chromosome changes. Previous evidence of differences in male and female gametogenesis could suggest an environmental role in the causation of the paternal 15q11-q13 deletion seen in PWS. Certain occupations such as hydrocarbon-exposing occupations (e.g., landscaping, farming, and painting) and viral exposure (e.g., human coronavirus 229E causing upper respiratory infections in adults with an incorporation site in the human genome at chromosome 15q11) can be seasonal in nature and contribute to chromosome damage. To assess, we reviewed birth seasonality data in a large cohort of individuals with PWS recruited nationally (N = 355) but no significant differences were seen by month between those with the 15q11-q13 deletion compared with maternal disomy 15 when analyzing quarterly seasonal patterns. Although early evidence supported birth seasonality differences in PWS, a larger number of individuals in our recent study using advanced genetic testing methods did not find this observation.

BackgroundPrader-Willi syndrome (PWS) is due to errors in genomic imprinting. PWS is recognised as the most common known genetic cause of life-threatening obesity. This report summarises the frequency and further characterises the PWS molecular classes and maternal age effects.MethodsHigh-resolution microarrays, comprehensive chromosome 15 genotyping and methylation-specific multiplex ligation probe amplification were used to describe and further characterise molecular classes of maternal disomy 15 (UPD15) considering maternal age.ResultsWe summarised genetic data from 510 individuals with PWS and 303 (60%) had the 15q11-q13 deletion; 185 (36%) with UPD15 and 22 (4%) with imprinting defects. We further characterised UPD15 findings into subclasses based on the presence (size, location) or absence of loss of heterozygosity (LOH). Additionally, significantly older mothers (mean age=32.5 years vs 27.7 years) were found in the UPD15 group (n=145) compared with the deletion subtype (n=200).ConclusionsWe report on molecular classes in PWS using advanced genomic technology in the largest cohort to date. LOH patterns in UPD15 may impact the risk of having a second genetic condition if the mother carries a recessive mutant allele in the isodisomic region on chromosome 15. The risk of UPD15 may also increase with maternal age.

Prader-Willi syndrome (PWS), is a complex genetic disease affecting 1/15,000 individuals, characterized by lack of expression of genes on the paternal chromosome 15q11-q13 region. Clinical features include central hypotonia, poor suck, learning and behavior problems, growth hormone deficiency with short stature, hyperphagia, and morbid obesity. Despite significant advances in genetic testing, the mean age for diagnosis in PWS continues to lag behind. Our goal was to perform a pilot feasibility study to confirm the diagnosis utilizing different genetic technologies in a cohort of 34 individuals with genetically confirmed PWS and 16 healthy controls from blood samples spotted and stored on newborn screening (NBS) filter paper cards. DNA was isolated from NBS cards, and PWS testing performed using DNA methylation-specific PCR (mPCR) and the methylation specific-multiplex ligation dependent probe amplification (MS-MLPA) chromosome 15 probe kit followed by DNA fragment analysis for methylation and copy number status. DNA extraction was successful in 30 of 34 PWS patients and 16 controls. PWS methylation testing was able to correctly identify all PWS patients and MS-MLPA was able to differentiate between 15q11-q13 deletion and non-deletion status and correctly identify deletion subtype (i.e., larger Type I or smaller Type II). mPCR can be used to diagnose PWS and MS-MLPA testing to determine both methylation status as well as the type of deletion or non-deletion status from DNA extracted from NBS filter paper. We propose that PWS testing in newborns is possible and could be included in the Recommended Uniform Screening Panel after establishing a validated cost-effective method.

Prader-Willi syndrome (PWS) is an imprinting genetic disorder characterized by lack of expression of genes on the paternal chromosome 15q11-q13 region. Growth hormone (GH) replacement positively influences stature and body composition in PWS. Our hypothesis was that early diagnosis delays onset of obesity in PWS. We studied 352 subjects with PWS, recruited from the NIH Rare Disease Clinical Research Network, to determine if age at diagnosis, ethnicity, gender, and PWS molecular class influenced the age they first become heavy, as determined by their primary care providers, and the age they first developed an increased appetite and began seeking food. The median ages that children with PWS became heavy were 10 years, 6 years and 4 years for age at diagnosis < 1 year, between 1 and 3 years, and greater than 3 years of age, respectively. The age of diagnosis and ethnicity were significant factors influencing when PWS children first became heavy (p < 0.01), however gender and the PWS molecular class had no influence. Early diagnosis delayed the onset of becoming heavy in individuals with PWS, permitting early GH and other treatment, thus reducing the risk of obesity-associated co-morbidities. Non-white individuals had an earlier onset of becoming heavy.

Prader-Willi syndrome (PWS) is a complex, multisystem genetic disorder characterized by endocrine, neurologic, and behavioral abnormalities. We report the first case of an unbalanced de novo reciprocal translocation of chromosomes 15 and 19, 45,XY,-15,der(19)t(15;19)(q12;p13.3), resulting in monosomy for the PWS critical chromosome region. Our patient had several typical features of PWS including infantile hypotonia, a poor suck and feeding difficulties, tantrums, skin picking, compulsions, small hands and feet, and food seeking, but not hypopigmentation, a micropenis, cryptorchidism or obesity as common findings seen in PWS at the time of examination at 6 years of age. He had seizures noted from 1 to 3 years of age and marked cognitive delay. High-resolution SNP microarray analysis identified an atypical PWS type I deletion in chromosome 15 involving the proximal breakpoint BP1. The deletion extended beyond the GABRB3 gene but was proximal to the usual distal breakpoint (BP3) within the 15q11q13 region, and GABRA5, GABRG3, and OCA2 genes were intact. No deletion of band 19p13.3 was detected; therefore, the patient was not at an increased risk of tumors from the Peutz-Jeghers syndrome associated with a deletion of the STK11 gene.

PurposePrader-Willi syndrome is an imprinting disorder characterized by typical facial, physical, and cognitive/behavioral features, resulting from lack of paternally expressed genes on chromosome 15q11.2-q13. Studies have suggested an increased risk of other imprinting disorders in children conceived by assisted reproductive techniques. This study was designed to determine the association between assisted reproductive technology and Prader-Willi syndrome.MethodsData on individuals with Prader-Willi syndrome were collected from three distinct sources and the proportion of assisted reproductive technology births analyzed.ResultsThe proportions of assisted reproductive technology births in the Prader-Willi Syndrome Association (USA), Rare Diseases Clinical Research Network, and University of California, Irvine Medical Center populations were 1.0% (18/1,736), 1.0% (1/98), and 2.0% (1/50), respectively (overall 1.1%; population frequency for the United States was 1.0%). Of note, 2.4% (45/1,898) of participants were co-twins (11 born after assisted reproductive technology procedures); US twin frequency is 1.6% (P = 0.007). The proportion of individuals with maternal disomy 15/imprinting defects born after assisted reproductive technology was higher than that in the total sample, 55.6% (10/18) and 34.5% (431/1,250), respectively.ConclusionThis study found no association between assisted reproductive technology and Prader-Willi syndrome. There was an increased frequency of twinning. The number of individuals with maternal disomy 15/imprinting defect was nearly double in the assisted reproductive technology group as compared with the total Prader-Willi syndrome participants.

PurposePrader-Willi syndrome (PWS) and Angelman syndrome (AS) are complex neurodevelopmental disorders caused by loss of expression of imprinted genes from the 15q11-q13 region depending on the parent of origin. Methylation-specific multiplex ligation-dependent probe amplification (MS-MLPA) kits from MRC-Holland (Amsterdam, The Netherlands) were used to detect PWS and AS deletion subtypes. We report our experience with two versions of the MS-MLPA-PWS/AS kit (original A1 and newer B1) in determining methylation status and deletion subtypes in individuals with PWS.MethodsMS-MLPA analysis was performed on DNA isolated from a large cohort of PWS subjects with the MS-MLPA-PWS/AS-A1 and -B1 probe sets.ResultsBoth MS-MLPA kits will identify deletions in the 15q11-q13 region but the original MS-MLPA-A1 kit has a higher density of probes at the telomeric end of the 15q11-q13 region, which is more useful for identifying individuals with atypical deletions. The newer B1 kit contains more probes in the imprinting center (IC) and adjoining small noncoding RNAs useful in identifying small microdeletions.ConclusionThe A1 kit identified the typical deletions and smaller atypical deletions, whereas the B1 kit was more informative for identifying microdeletions including the IC and SNORD116 regions. Both kits should be made available for accurate characterization of PWS/AS deletion subtypes as well as evaluating for IC and SNORD116 microdeletions.

BackgroundPrader-Willi syndrome (PWS) is a complex genetic disorder with errors in genomic imprinting, generally due to a paternal deletion of chromosome 15q11-q13 region. Maternal disomy 15 (both 15s from the mother) is the second most common form of PWS resulting from a trisomic zygote followed by trisomy rescue in early pregnancy and loss of the paternal chromosome 15. However, trisomy 15 or mosaicism for trisomy 15 may be present in the placenta possibly leading to placental abnormalities affecting gestational age and delivery.Methods and subjectsWe examined growth and gestational data from 167 PWS infants (93 males and 74 females; 105 infants with 15q11-q13 deletion and 62 infants with maternal disomy 15) to determine if there are differences in gestation between the two genetic subtypes.ResultsNo significant differences in growth data (birth weight, length, head circumference) or average gestational ages were found between the two genetic subgroups. However, post-term deliveries (> 42 weeks gestation) were more common in the maternal disomy group (i.e., 12 of 62 infants) compared with the deletion group (i.e., 7 of 105 infants) (chi-square test = 6.22; p < 0.02). The distribution of gestational ages in the 15q11-q13 deletion group was more bell-shaped or normal while the distribution in the maternal disomy group suggested a bimodal pattern.ConclusionsMaternal disomy 15 in PWS may contribute to disturbances in gestational age and delivery by impacting on placental structure or function secondary to the abnormal chromosomal number in the placental cells or in mechanisms leading to the maternal disomy status in PWS infants.

Prader–Willi syndrome (PWS) is a complex genetic disorder with three PWS molecular genetic classes and presents as severe hypotonia, failure to thrive, hypogonadism/hypogenitalism and developmental delay during infancy. Hyperphagia, obesity, learning and behavioral problems, short stature with growth and other hormone deficiencies are identified during childhood. Those with the larger 15q11-q13 Type I deletion with the absence of four non-imprinted genes (NIPA1, NIPA2, CYFIP1, TUBGCP5) from the 15q11.2 BP1-BP2 region are more severely affected compared with those with PWS having a smaller Type II deletion. NIPA1 and NIPA2 genes encode magnesium and cation transporters, supporting brain and muscle development and function, glucose and insulin metabolism and neurobehavioral outcomes. Lower magnesium levels are reported in those with Type I deletions. The CYFIP1 gene encodes a protein associated with fragile X syndrome. The TUBGCP5 gene is associated with attention-deficit hyperactivity disorder (ADHD) and compulsions, more commonly seen in PWS with the Type I deletion. When the 15q11.2 BP1-BP2 region alone is deleted, neurodevelopment, motor, learning and behavioral problems including seizures, ADHD, obsessive-compulsive disorder (OCD) and autism may occur with other clinical findings recognized as Burnside–Butler syndrome. The genes in the 15q11.2 BP1-BP2 region may contribute to more clinical involvement and comorbidities in those with PWS and Type I deletions. [ABSTRACT FROM AUTHOR]

A high-resolution chromosome microarray analysis was performed on 154 consecutive individuals enrolled in the DESTINY PWS clinical trial for Prader-Willi syndrome (PWS). Of these 154 PWS individuals, 87 (56.5%) showed the typical 15q11-q13 deletion subtypes, 62 (40.3%) showed non-deletion maternal disomy 15 and five individuals (3.2%) had separate unexpected microarray findings. For example, one PWS male had Klinefelter syndrome with segmental isodisomy identified in both chromosomes 15 and X. Thirty-five (40.2%) of 87 individuals showed typical larger 15q11-q13 Type I deletion and 52 individuals (59.8%) showed typical smaller Type II deletion. Twenty-four (38.7%) of 62 PWS individuals showed microarray patterns indicating either maternal heterodisomy 15 subclass or a rare non-deletion (epimutation) imprinting center defect. Segmental isodisomy 15 was seen in 34 PWS subjects (54.8%) with 15q26.3, 15q14 and 15q26.1 bands most commonly involved and total isodisomy 15 seen in four individuals (6.5%). In summary, we report on PWS participants consecutively enrolled internationally in a single clinical trial with high-resolution chromosome microarray analysis to determine and describe an unbiased estimate of the frequencies and types of genetic defects and address potential at-risk genetic disorders in those with maternal disomy 15 subclasses in the largest PWS cohort studied to date. [ABSTRACT FROM AUTHOR]

Prader-Willi syndrome (PWS) is a complex, multisystem genetic disorder characterized by endocrine, neurologic, and behavioral abnormalities. We report the first case of an unbalanced de novo reciprocal translocation of chromosomes 15 and 19, 45,XY,-15,der(19)t(15; 19)(q12;p13.3), resulting in monosomy for the PWS critical chromosome region. Our patient had several typical features of PWS including infantile hypotonia, a poor suck and feeding difficulties, tantrums, skin picking, compulsions, small hands and feet, and food seeking, but not hypopigmentation, a micropenis, cryptorchidism or obesity as common findings seen in PWS at the time of examination at 6 years of age. He had seizures noted from 1 to 3 years of age and marked cognitive delay. High-resolution SNP microarray analysis identified an atypical PWS type I deletion in chromosome 15 involving the proximal breakpoint BP1. The deletion extended beyond the GA-BRB3 gene but was proximal to the usual distal breakpoint (BP3) within the 15q11q13 region, and GABRA5, GABRG3, and OCA2 genes were intact. No deletion of band 19p13.3 was detected; therefore, the patient was not at an increased risk of tumors from the Peutz-Jeghers syndrome associated with a deletion of the STK11 gene. [ABSTRACT FROM AUTHOR]

Recently, autism-related research has focused on the identification of various genes and disturbed pathways causing the genetically heterogeneous group of autism spectrum disorders (ASD). The list of autism-related genes has significantly increased due to better awareness with advances in genetic technology and expanding searchable genomic databases. We compiled a master list of known and clinically relevant autism spectrum disorder genes identified with supporting evidence from peer-reviewed medical literature sources by searching key words related to autism and genetics and from authoritative autism-related public access websites, such as the Simons Foundation Autism Research Institute autism genomic database dedicated to gene discovery and characterization. Our list consists of 792 genes arranged in alphabetical order in tabular form with gene symbols placed on high-resolution human chromosome ideograms, thereby enabling clinical and laboratory geneticists and genetic counsellors to access convenient visual images of the location and distribution of ASD genes. Meaningful correlations of the observed phenotype in patients with suspected/confirmed ASD gene(s) at the chromosome region or breakpoint band site can be made to inform diagnosis and gene-based personalized care and provide genetic counselling for families. [ABSTRACT FROM AUTHOR]

Background Omphalocele is a congenital birth defect characterised by the presence of internal organs located outside of the ventral abdominal wall. The purpose of this study was to identify the underlying genetic mechanisms of a large autosomal dominant Caucasian family with omphalocele. Methods and findings A genetic linkage study was conducted in a large family with an autosomal dominant transmission of an omphalocele using a genome-wide single nucleotide polymorphism (SNP) array. The analysis revealed significant evidence of linkage (non-parametric NPL = 6.93, p=0.0001; parametric logarithm of odds (LOD) = 2.70 under a fully penetrant dominant model) at chromosome band 1p31.3. Haplotype analysis narrowed the locus to a 2.74 Mb region between markers rs2886770 (63014807 bp) and rs1343981 (65757349 bp). Molecular characterisation of this interval using array comparative genomic hybridisation followed by quantitative microsphere hybridisation analysis revealed a 710 kb duplication located at 63.5e64.2 Mb. All affected individuals who had an omphalocele and shared the haplotype were positive for this duplicated region, while the duplication was absent from all normal individuals of this family. Multipoint linkage analysis using the duplication as a marker yielded a maximum LOD score of 3.2 at 1p31.3 under a dominant model. The 710 kb duplication at 1p31.3 band contains seven known genes including FOXD3, ALG6, ITGB3BP, KIAA1799, DLEU2L, PGM1, and the proximal portion of ROR1. Importantly, this duplication is absent from the database of genomic variants. Conclusions The present study suggests that development of an omphalocele in this family is controlled by overexpression of one or more genes in the duplicated region. To the authors' knowledge, this is the first reported association of an inherited omphalocele condition with a chromosomal rearrangement. [ABSTRACT FROM AUTHOR]

Mammals inherit two complete sets of chromosomes, one from the father and one from the mother, and most autosomal genes are expressed from both maternal and paternal alleles. Imprinted genes show expression from only one member of the gene pair (allele) and their expression are determined by the parent during production of the gametes. Imprinted genes represent only a small subset of mammalian genes that are present but not imprinted in other vertebrates. Genomic imprints are erased in both germlines and reset accordingly; thus, reversible depending on the parent of origin and leads to differential expression in the course of development. Genomic imprinting has been studied in humans since the early 1980's and accounts for several human disorders. The first report in humans occurred in Prader-Willi syndrome due to a paternal deletion of chromosome 15 or uniparental disomy 15 (both chromosome 15s from only one parent) and similar genetic disturbances were reported later in Angelman syndrome. [ABSTRACT FROM AUTHOR]

Comments on a study which discussed the occurrence of genetic alteration chromosomal duplication in a family with Cowden's disease. Information on the molecular genetic and cytogenetic analysis with chromosome 15q11-q13 in the family; Details of the polymerase chain reaction analysis undertaken with several DNA microsatellite markers in the chromosome; Incidence of chromosomal abnormalities in patients with the disease.

Objective Alcoholism arises from combined effects of multiple biological factors including genetic and non-genetic causes with gene/environmental interaction. Intensive research and advanced genetic technology has generated a long list of genes and biomarkers involved in alcoholism neuropathology. These markers reflect complex overlapping and competing effects of possibly hundreds of genes which impact brain structure, function, biochemical alcohol processing, sensitivity and risk for dependence. Method We compiled a tabular list of clinically relevant genetic biomarkers for alcoholism targeting expression disturbances in the human brain through an extensive search of keywords related to alcoholism, alcohol abuse, and genetics from peer reviewed medical research articles and related nationally sponsored websites. Gene symbols were then placed on high resolution human chromosome ideograms with gene descriptions in tabular form. Results We identified 337 clinically relevant genetic biomarkers and candidate genes for alcoholism and alcohol-responsiveness from human brain research. Genetic biomarkers included neurotransmitter pathways associated with brain reward processes for dopaminergic (e.g., DRD2 , MAOA , and COMT ), serotoninergic (e.g., HTR3A , HTR1B , HTR3B , and SLC6A4 ), GABAergic (e.g., GABRA1 , GABRA2 , and GABRG1 ), glutaminergic ( GAD1 , GRIK3 , and GRIN2C ) and opioid (e.g., OPRM1 , OPRD1 , and OPRK1 ) pathways which presumably impact reinforcing properties of alcohol. Gene level disturbances in cellular and molecular networks impacted by alcohol and alcoholism pathology include transketolase (TKT), transferrin (TF), and myelin (e.g., MBP, MOBP, and MOG). Conclusions High resolution chromosome ideograms provide investigators, physicians, geneticists and counselors a convenient visual image of the distribution of alcoholism genetic biomarkers from brain research with alphabetical listing of genes in tabular form allowing comparison between alcoholism-related phenotypes, and clinically-relevant alcoholism gene(s) at the chromosome band level to guide research, diagnosis, and treatment. Chromosome ideograms may facilitate gene-based personalized counseling of alcohol dependent individuals and their families. [ABSTRACT FROM AUTHOR]

Bipolar disorder (BPD) is genetically heterogeneous with a growing list of BPD associated genes reported in recent years resulting from increased genetic testing using advanced genetic technology, expanded genomic databases, and better awareness of the disorder. We compiled a master list of recognized susceptibility and genes associated with BPD identified from peer-reviewed medical literature sources using PubMed and by searching online databases, such as OMIM. Searched keywords were related to bipolar disorder and genetics. Our compiled list consisted of 290 genes with gene names arranged in alphabetical order in tabular form with source documents and their chromosome location and gene symbols plotted on high-resolution human chromosome ideograms. The identified genes impacted a broad range of biological pathways and processes including cellular signaling pathways particularly cAMP and calcium (e.g., CACNA1C , CAMK2A , CAMK2D , ADCY1 , ADCY2 ); glutamatergic (e.g., GRIK1 , GRM3 , GRM7 ), dopaminergic (e.g., DRD2 , DRD4 , COMT , MAOA ) and serotonergic ( e.g., HTR1A , HTR2A , HTR3B ) neurotransmission; molecular transporters (e.g., SLC39A3, SLC6A3, SLC8A1); and neuronal growth (e.g., BDNF , IGFBP1 , NRG1 , NRG3 ). The increasing prevalence of BPD calls for better understanding of the genetic etiology of this disorder and associations between the observed BPD phenotype and genes. Visual representation of genes for bipolar disorder becomes a tool enabling clinical and laboratory geneticists, genetic counselors, and other health care providers and researchers easy access to the location and distribution of currently recognized BPD associated genes. Our study may also help inform diagnosis and advance treatment developments for those affected with this disorder and improve genetic counseling for families. [ABSTRACT FROM AUTHOR]

Abstract: Chromosomal microarray analysis is now commonly used in clinical practice to identify copy number variants (CNVs) in the human genome. We report our experience with the use of the 105K and 180K oligonucleotide microarrays in 215 consecutive patients referred with either autism or autism spectrum disorders (ASD) or developmental delay/learning disability for genetic services at the University of Kansas Medical Center during the past 4years (2009–2012). Of the 215 patients [140 males and 75 females (male/female ratio=1.87); 65 with ASD and 150 with learning disability], abnormal microarray results were seen in 45 individuals (21%) with a total of 49 CNVs. Of these findings, 32 represented a known diagnostic CNV contributing to the clinical presentation and 17 represented non-diagnostic CNVs (variants of unknown significance). Thirteen patients with ASD had a total of 14 CNVs, 6 CNVs recognized as diagnostic and 8 as non-diagnostic. The most common chromosome involved in the ASD group was chromosome 15. For those with a learning disability, 32 patients had a total of 35 CNVs. Twenty-six of the 35 CNVs were classified as a known diagnostic CNV, usually a deletion (n=20). Nine CNVs were classified as an unknown non-diagnostic CNV, usually a duplication (n=8). For the learning disability subgroup, chromosomes 2 and 22 were most involved. Thirteen out of 65 patients (20%) with ASD had a CNV compared with 32 out of 150 patients (21%) with a learning disability. The frequency of chromosomal microarray abnormalities compared by subject group or gender was not statistically different. A higher percentage of individuals with a learning disability had clinical findings of seizures, dysmorphic features and microcephaly, but not statistically significant. While both groups contained more males than females, a significantly higher percentage of males were present in the ASD group. [Copyright &y& Elsevier]

Context.—Cytogenetic heteromorphisms (normal variants) pose diagnostic dilemmas. Common Giemsa-band heteromorphisms are not described in the literature, although Giemsa-banding is the method most frequently used in cytogenetic laboratories. Objective.—To summarize the responses from more than 200 cytogeneticists concerning the definition and reporting of cytogenetic heteromorphisms, to offer these responses as a reference for use in clinical interpretations, and to provide guidance for interpretation of newly defined molecular cytogenetic heteromorphisms. Design.—The Cytogenetics Resource Committee of the College of American Pathologists and the American College of Medical Genetics administered a proficiency testing survey in 1997 to 226 participant cytogenetic laboratories. Supplemental questions asked whether participants considered particular Giemsa-banded chromosomal features to be heteromorphisms and if these would be described in a cytogenetic clinical report. Results.—Responses were obtained from 99% of participants; 61% stated they would include selected heteromorphism data in a clinical report. More than 90% considered prominent short arms, large or double satellites, or increased stalk length on acrocentric chromosomes to be heteromorphisms; 24% to 36% stated that they would include these in a clinical report. Heterochromatic regions on chromosomes 1, 9, 16, and Y were considered heteromorphisms by 97% of participants, and 24% indicated they would report these findings. Pericentric inversions of chromosomes 1, 2, 3, 5, 9, 10, 16, and Y were considered heteromorphisms with more than 75% of respondents indicating they would report these findings. Conclusions.—Responses were not unanimous, but a clear consensus is presented describing which Giemsaband regions were considered heteromorphisms and which would be reported. [ABSTRACT FROM AUTHOR]