Further characterization of microdeletion syndrome involving 2p15-p16.1

Rare Case of de Novo 2p15 Microdeletion Syndrome with Deletion Covering XPO1 and USP34 Genes Diagnosed in a Child - A Case Report

Introduction

2p15p16.1 microdeletion syndrome was described for the first time in 2007. The size of the microdeletion is variable and encompasses several genes, like XPO1, USP34, BCL11A, REL, PAPOLG, PEX13, COMMD1, B3GNT2, and EHBP1. Features of the syndrome include short stature, microcephaly, hypotonia, psychomotor developmental delay, anomalies of the fingers of the upper and lower limbs, dysmorphic features like receding forehead, broad nasal bridge, telecanthus, ptosis, flat philtrum, small mouth with a high, narrow palate and everted lower lip. The precise genotype-phenotype correlation in 2p15 deletion syndrome is not understood. The aim of the study is to present the patient's medical history and the diagnostic process.

Case Presentation

A boy aged 9 was admitted to the Genetic Outpatient Clinic due to dysmorphic features and mild mental retardation. Full lips, broad nasal root, very light hair, excessively developed subcutaneous tissue, joint laxity, postural defect, flat-valgus foot with sandal gap, brachydactyly, and problems with concentration, memory, and counting were found. Diagnosis was based on microarray testing, and copy-number variation analysis was performed using CytoScan 750K array. Genetic imbalance in the form of a deletion within the short arm of chromosome 2 in the 2p15 region (containing 50 kbp) was shown. The microdeletion covers 2 genes: USP34 and XPO1. Parents were not carriers of that mutation.

Conclusion

The phenotypic features presented by the patient were reflected in the genetic test. 2p15 microdeletion syndrome is genetically heterogeneous with possible de novo occurrence, as in the presented case. The precise genotype-phenotype correlation in 2p15 deletion syndrome should be widely studied because in the literature there is mainly mentioned 2p15p16.1 syndrome. Even though 2p15 microdeletion syndrome is a rare discovery and its features are mainly mild, it is necessary to pay special attention to them to refer patients to genetic counseling to make an accurate diagnosis.

Trait - driven analysis of the 2p15p16.1 microdeletion syndrome suggests a complex pattern of interactions between candidate genes

BACKGROUND

Individuals with the 2p15p16.1 microdeletion syndrome share a complex phenotype including neurodevelopmental delay, brain malformations, microcephaly, and autistic behavior. The analysis of the shortest region of overlap (SRO) between deletions in ~ 40 patients has led to the identification of two critical regions and four strongly candidate genes (BCL11A, REL, USP34 and XPO1). However, the delineation of their role in the occurrence of specific traits is hampered by their incomplete penetrance.

OBJECTIVE

To better delineate the role of hemizygosity of specific regions in selected traits by leveraging information both from penetrant and non - penetrant deletions.

METHODS

Deletions in patients that do not present a specific trait cannot contribute to delineate the SROs. We recently developed a probabilistic model that, by considering also the non - penetrant deletions, allows a more reliable assignment of peculiar traits to specific genomic segments. We apply this method adding two new patients to the published cases.

RESULTS

Our results delineate an intricate pattern of genotype - phenotype correlation where BCL11A emerges as the main gene for autistic behavior while USP34 and/or XPO1 haploinsufficiency are mainly associated with microcephaly, hearing loss and IUGR. BCL11A, USP34 and XPO1 genes are broadly related with brain malformations albeit with distinct patterns of brain damage.

CONCLUSIONS

The observed penetrance of deletions encompassing different SROs and that predicted when considering each single SRO as acting independently, may reflect a more complex model than the additive one. Our approach may improve the genotype/phenotype correlation and may help to identify specific pathogenic mechanisms in contiguous gene syndromes.

Copy Number Variations in Children with Tourette Syndrome: Systematic Investigation in a Clinical Setting

Tourette syndrome (TS) is a neurodevelopmental disturbance with heterogeneous and not completely known etiology. Clinical and molecular appraisal of affected patients is mandatory for outcome amelioration. The current study aimed to understand the molecular bases underpinning TS in a vast cohort of pediatric patients with TS. Molecular analyses included array-CGH analyses. The primary goal was to define the neurobehavioral phenotype of patients with or without pathogenic copy number variations (CNVs). Moreover, we compared the CNVs with CNVs described in the literature in neuropsychiatric disorders, including TS, to describe an effective clinical and molecular characterization of patients for prognostic purposes and for correctly taking charge. Moreover, this study showed that rare deletions and duplications focusing attention on significant genes for neurodevelopment had a statistically higher occurrence in children with tics and additional comorbidities. In our cohort, we determined an incidence of potentially causative CNVs of about 12%, in line with other literature studies. Clearly, further studies are needed to delineate the genetic background of patients with tic disorders in a superior way to elucidate the complex genetic architecture of these disorders, to describe the outcome, and to identify new possible therapeutic targets.

Three children with different de novo BCL11A variants and diverse developmental phenotypes, but shared global motor discoordination and apraxic speech: Evidence for a functional gene network influencing the developing cerebellum and motor and auditory cortices

BCL11A is implicated in BCL11A-Related Intellectual Development Disorder (BCL11A-IDD). Previously reported cases had various types of BCL11A variants (copy-number variations [CNVs], singlenucleotide variants [SNVs]). Phenotypes included global, cognitive, and motor delays, autism spectrum disorder (ASD), craniofacial dysmorphology, and speech and language delays described generally, with only two reports specifying childhood apraxia of speech (CAS). Here, we present three additional children with CAS and de novo BCL11A variants, a p.Ala182Thr nonconservative missense and a p.GLu611.Ter nonsense variant, both in exon 4, and a 106 kb deletion harboring exons 1 and 2. All three children have fine and gross motor discoordination, feeding difficulties, and visual motor disorders. Intellectual and learning disabilities and disordered language skills were seen only in the child with the missense variant and the child with the deletion. These findings align with, and expand, previous findings in that BCL11A variants have significant and highly penetrant apraxic effects across motor systems, consistent with cerebellar involvement. The deletion of exons 1 and 2 is the smallest BCL11A CNV with the full phenotypic expression reported to date. The present results support previous findings in that BCL11A-IDD can result from BCL11A variants regardless of type (deletion, SNVs). A gene expression study shows that BCL11 is expressed highly in the early developing cerebellum and primary motor and auditory cortices. Significant co-expression rates in these regions with genes previously implicated in disorders of spoken language and in ASD support the phenotypic overlaps in children with BCL11A-IDD, CAS, and ASD.

Inhibition of Autism-Related Crm1 Disrupts Mitosis and Induces Apoptosis of the Cortical Neural Progenitors

De novo microdeletion of chromosome 2p15-16.1 presents clinically recognizable phenotypes that include mental retardation, autism, and microcephaly. Chromosomal maintenance 1 (CRM1) is a gene commonly missing in patients with 2p15-16.1 microdeletion and one of two genes found in the smallest deletion case. In this study, we investigate the role and mechanism of Crm1 in the developing mouse brain by inhibiting the protein or knocking down the gene in vivo. Inhibition of Crm1 reduces the proliferation and increases p53-dependent apoptosis of the cortical neural progenitors, thereby impeding the growth of embryonic cerebral cortex. Live imaging of mitosis in ex vivo embryonic brain slices reveals that inhibition of CRM1 arrests the cortical progenitors at metaphase. The arrested cells eventually slip into a pseudo-G1 phase without chromosome segregation. The mitotic slippage cells are marked by persistent expression of the spindle assembly checkpoint (SAC), repressing of which rescues the cells from apoptosis. Our study reveals that activating the SAC and inducing the mitotic slippage may lead to apoptosis of the cortical neural progenitors. The resulting cell death may well contribute to microcephaly associated with microdeletion of chromosome 2p15-16.1 involving CRM1.

Prenatal diagnosis of a 3.2-Mb 2p16.1-p15 duplication associated with familial intellectual disability

OBJECTIVE

We present prenatal diagnosis of a 2p16.1-p15 duplication associated with familial intellectual disability, and we discuss the genotype-phenotype correlation.

CASE REPORT

A 22-year-old, primigravid woman underwent amniocentesis at 22 weeks of gestation because of a family history of intellectual disability. The woman and her two sisters had intellectual disability but no behavioral disorders. The intellectual disability was noted in at least one paternal aunt and six paternal cousins of the woman. Cytogenetic analysis revealed the karyotype of 46,XX in the fetus and the two women. Array comparative genomic hybridization (aCGH) analysis on the DNAs extracted from cultured amniocytes and the bloods of the woman and the her sister revealed a 3.244-Mb duplication of 2p16.1-p15 or arr 2p16.1p15 (58,288,588-61,532,538) × 3.0 [GRCh37 (hg19)] encompassing eight Online Mendelian Inheritance in Man (OMIM) genes of VRK2, FANCL, BCL11A, PAPOLG, REL, PUS10, PEX13 and USP34 in the fetus and the two women. Prenatal ultrasound findings were unremarkable. The woman elected to continue the pregnancy. A 3244-g female baby was delivered at term with neither craniofacial dysmorphism nor structural abnormalities.

CONCLUSION

aCGH is useful in prenatal diagnosis of inherited subtle chromosome imbalance in pregnancy with familial intellectual disability. Chromosome 2p16.1-p15 duplication can be associated with intellectual disability.

Microduplication in the 2p16.1p15 chromosomal region linked to developmental delay and intellectual disability

Background

Several patients with the 2p16.1p15 microdeletion syndrome have been reported. However, microduplication in the 2p16.1p15 chromosomal region has only been reported in one case, and milder clinical features were present compared to those attributed to 2p16.1p15 microdeletion syndrome. Some additional cases were deposited in DECIPHER database.

Case presentation

In this report we describe four further cases of 2p16.1p15 microduplication in four unrelated probands. They presented with mild gross motor delay, delayed speech and language development, and mild dysmorphic features. In addition, two probands have macrocephaly and one a congenital heart anomaly. Newly described cases share several phenotype characteristics with those detailed in one previously reported microduplication case.

Conclusion

The common features among patients are developmental delay, speech delay, mild to moderate intellectual disability and unspecific dysmorphic features. Two patients have bilateral clinodactyly of the 5th finger and two have bilateral 2nd-3rd toes syndactyly. Interestingly, as opposed to the deletion phenotype with some cases of microcephaly, 2 patients are reported with macrocephaly. The reported cases suggest that microduplication in 2p16.1p15 chromosomal region might be causally linked to developmental delay, speech delay, and mild intellectual disability.

BCL11A frameshift mutation associated with dyspraxia and hypotonia affecting the fine, gross, oral, and speech motor systems

We report the case of a 7‐year‐old male of Western European origin presenting with moderate intellectual disability, severe childhood apraxia of speech in the presence of oral and manual dyspraxia, and hypotonia across motor systems including the oral and speech motor systems. Exome sequencing revealed a de novo frameshift protein truncating mutation in the fourth exon of BCL11A, a gene recently demonstrated as being involved in cognition and language development. Making parallels with a previously described patient with a 200 kb 2p15p16.1 deletion encompassing the entire BCL11A gene and displaying a similar phenotype, we characterize in depth how BCL11A is involved in clinical aspects of language development and oral praxis.

Chromosomal contacts connect loci associated with autism, BMI and head circumference phenotypes

Copy number variants (CNVs) are major contributors to genomic imbalance disorders. Phenotyping of 137 unrelated deletion and reciprocal duplication carriers of the distal 16p11.2 220 kb BP2-BP3 interval showed that these rearrangements are associated with autism spectrum disorders and mirror phenotypes of obesity/underweight and macrocephaly/microcephaly. Such phenotypes were previously associated with rearrangements of the non-overlapping proximal 16p11.2 600 kb BP4-BP5 interval. These two CNV-prone regions at 16p11.2 are reciprocally engaged in complex chromatin looping, as successfully confirmed by 4C-seq, fluorescence in situ hybridization and Hi-C, as well as coordinated expression and regulation of encompassed genes. We observed that genes differentially expressed in 16p11.2 BP4-BP5 CNV carriers are concomitantly modified in their chromatin interactions, suggesting that disruption of chromatin interplays could participate in the observed phenotypes. We also identified cis- and trans-acting chromatin contacts to other genomic regions previously associated with analogous phenotypes. For example, we uncovered that individuals with reciprocal rearrangements of the trans-contacted 2p15 locus similarly display mirror phenotypes on head circumference and weight. Our results indicate that chromosomal contacts' maps could uncover functionally and clinically related genes.

Haploinsufficiency of BCL11A associated with cerebellar abnormalities in 2p15p16.1 deletion syndrome

BACKGROUND

Chromosome 2p15p16.1 deletion syndrome is a rare genetic disorder characterized by intellectual disability (ID), neurodevelopmental delay, language delay, growth retardation, microcephaly, structural brain abnormalities, and dysmorphic features. More than 30 patients with 2p15p16.1 microdeletion syndrome have been reported in the literature.

METHODS

Molecular analysis was performed using microarray-based comparative genomic hybridization (array CGH). Clinical characteristics and brain magnetic resonance imaging features of these patients were also reviewed.

RESULTS

We identified four patients with ID, neurodevelopmental delay, brain malformations, and dysmorphic features; two patients with 2p15p16.1 deletions (3.24 Mb, 5.04 Mb), one patient with 2p16.1 deletion (1.12 Mb), and one patient with 2p14p16.1 deletion (5.12 Mb). Three patients with 2p15p16.1 deletions or 2p16.1 deletions encompassing BCL11A,PAPOLG, and REL showed hypoplasia of the pons and cerebellum. The patient with 2p14p16.1 deletion, which did not include three genes showed normal size and shape of the cerebellar hemispheres and pons.

CONCLUSION

The zinc finger transcription factor BCL11A associated with the BAF chromatin remodeling complex has been identified to be critical for neural development and BCL11A haploinsufficiency is closely related to cerebellar abnormalities.

De novo 2p16.1 microdeletion with metastatic esophageal adenocarcinoma

Microdeletions involving chromosome 2p15-16.1 are a rare genetic abnormality and have been reported in 18 separate patients, mainly children, since 2007. This microdeletion syndrome is characterised by a heterogeneous expression of intellectual impairment, dysmorphic facies, musculoskeletal abnormalities and potential neurodevelopmental anomalies. We report the first case of natural progression in an adult patient who died at a young age of metastatic esophageal adenocarcinoma. Important learning points include the variable phenotypic expression of this microdeletion syndrome and the fact that clinicians must be thorough in investigating objective discrepancies in patients who cannot endorse classical symptoms.

BCL11A Haploinsufficiency Causes an Intellectual Disability Syndrome and Dysregulates Transcription

Intellectual disability (ID) is a common condition with considerable genetic heterogeneity. Next-generation sequencing of large cohorts has identified an increasing number of genes implicated in ID, but their roles in neurodevelopment remain largely unexplored. Here we report an ID syndrome caused by de novo heterozygous missense, nonsense, and frameshift mutations in BCL11A, encoding a transcription factor that is a putative member of the BAF swi/snf chromatin-remodeling complex. Using a comprehensive integrated approach to ID disease modeling, involving human cellular analyses coupled to mouse behavioral, neuroanatomical, and molecular phenotyping, we provide multiple lines of functional evidence for phenotypic effects. The etiological missense variants cluster in the amino-terminal region of human BCL11A, and we demonstrate that they all disrupt its localization, dimerization, and transcriptional regulatory activity, consistent with a loss of function. We show that Bcl11a haploinsufficiency in mice causes impaired cognition, abnormal social behavior, and microcephaly in accordance with the human phenotype. Furthermore, we identify shared aberrant transcriptional profiles in the cortex and hippocampus of these mouse models. Thus, our work implicates BCL11A haploinsufficiency in neurodevelopmental disorders and defines additional targets regulated by this gene, with broad relevance for our understanding of ID and related syndromes.

Genetic Candidate Variants in Two Multigenerational Families with Childhood Apraxia of Speech

Childhood apraxia of speech (CAS) is a severe and socially debilitating form of speech sound disorder with suspected genetic involvement, but the genetic etiology is not yet well understood. Very few known or putative causal genes have been identified to date, e.g., FOXP2 and BCL11A. Building a knowledge base of the genetic etiology of CAS will make it possible to identify infants at genetic risk and motivate the development of effective very early intervention programs. We investigated the genetic etiology of CAS in two large multigenerational families with familial CAS. Complementary genomic methods included Markov chain Monte Carlo linkage analysis, copy-number analysis, identity-by-descent sharing, and exome sequencing with variant filtering. No overlaps in regions with positive evidence of linkage between the two families were found. In one family, linkage analysis detected two chromosomal regions of interest, 5p15.1-p14.1, and 17p13.1-q11.1, inherited separately from the two founders. Single-point linkage analysis of selected variants identified CDH18 as a primary gene of interest and additionally, MYO10, NIPBL, GLP2R, NCOR1, FLCN, SMCR8, NEK8, and ANKRD12, possibly with additive effects. Linkage analysis in the second family detected five regions with LOD scores approaching the highest values possible in the family. A gene of interest was C4orf21 (ZGRF1) on 4q25-q28.2. Evidence for previously described causal copy-number variations and validated or suspected genes was not found. Results are consistent with a heterogeneous CAS etiology, as is expected in many neurogenic disorders. Future studies will investigate genome variants in these and other families with CAS.

Identifying candidate genes for 2p15p16.1 microdeletion syndrome using clinical, genomic, and functional analysis

The 2p15p16.1 microdeletion syndrome has a core phenotype consisting of intellectual disability, microcephaly, hypotonia, delayed growth, common craniofacial features, and digital anomalies. So far, more than 20 cases of 2p15p16.1 microdeletion syndrome have been reported in the literature; however, the size of the deletions and their breakpoints vary, making it difficult to identify the candidate genes. Recent reports pointed to 4 genes (XPO1, USP34, BCL11A, and REL) that were included, alone or in combination, in the smallest deletions causing the syndrome. Here, we describe 8 new patients with the 2p15p16.1 deletion and review all published cases to date. We demonstrate functional deficits for the above 4 candidate genes using patients' lymphoblast cell lines (LCLs) and knockdown of their orthologs in zebrafish. All genes were dosage sensitive on the basis of reduced protein expression in LCLs. In addition, deletion of XPO1, a nuclear exporter, cosegregated with nuclear accumulation of one of its cargo molecules (rpS5) in patients' LCLs. Other pathways associated with these genes (e.g., NF-κB and Wnt signaling as well as the DNA damage response) were not impaired in patients' LCLs. Knockdown of xpo1a, rel, bcl11aa, and bcl11ab resulted in abnormal zebrafish embryonic development including microcephaly, dysmorphic body, hindered growth, and small fins as well as structural brain abnormalities. Our multifaceted analysis strongly implicates XPO1, REL, and BCL11A as candidate genes for 2p15p16.1 microdeletion syndrome.

A de-novo interstitial microduplication involving 2p16.1-p15 and mirroring 2p16.1-p15 microdeletion syndrome: Clinical and molecular analysis

BACKGROUND

Microdeletions of various sizes in the 2p16.1-p15 chromosomal region have been grouped together under the 2p16.1-p15 microdeletion syndrome. Children with this syndrome generally share certain features including microcephaly, developmental delay, facial dysmorphism, urogenital and skeletal abnormalities. We present a child with a de-novo interstitial 1665 kb duplication of 2p16.1-p15.

METHODS AND RESULTS

Clinical features of this child are distinct from those of children with the 2p16.1-p15 microdeletion syndrome, specifically the head circumference which is within the normal range and mild intellectual disability with absence of autistic behaviors. Microduplications many times bear milder clinical phenotypes in comparison with corresponding microdeletion syndromes. Indeed, as compared to the microdeletion syndrome patients, the 2p16.1-p15 microduplication seems to have a milder cognitive effect and no effect on other body systems. Limited information available in genetic databases about cases with overlapping duplications indicates that they all have abnormal developmental phenotypes.

CONCLUSION

The involvement of genes in this location including BCL11A, USP34 and PEX13, affecting fundamental developmental processes both within and outside the nervous system may explain the clinical features of the individual described in this report.

Characteristics of 2p15-p16.1 microdeletion syndrome: Review and description of two additional patients

Many new microdeletion syndromes have been characterized in the past decade, including 2p15-p16.1 microdeletion syndrome. More than 10 patients with this syndrome have been described. Recently, we encountered two additional patients with 2p15-p16.1 microdeletion syndrome. All patients showed variable degrees of intellectual disability, with the autistic features characteristic of this syndrome. Seven out of 16 patients (44%) showed structural abnormalities in the brain, which is also an important feature of this syndrome. The shortest region of microdeletion overlap among the patients includes two genes, USP34 and XPO1. Although these genes have some functional relevance to cancer, they have not been associated with neurological functions. Diagnosis of additional patients with 2p15-p16.1 microdeletion syndrome and identification of pathogenic mutations in this region will help identify the genes responsible for the neurological features of the syndrome.

Brain malformations in a patient with deletion 2p16.1: A refinement of the phenotype to BCL11A

Microdeletions of 2p15-16.1 have been reported in 15 patients with a recognizable syndrome of dysmorphic features, intellectual disability and microcephaly. Facial features include telecanthus, short palpebral fissures, epicanthal folds, a broad nasal root, smooth and long philtrum and large ears. Brain malformations can be observed in this syndrome and include hypoplasia of the corpus callosum and a simplified cortical gyral pattern. Case reports have narrowed the critical region of the neurodevelopmental phenotype to a region that spans the B-cell CLL/lymphoma 11A (BCL11A) gene. Here we present a 3-year-old normocephalic girl with moderate development delay and dysmorphic features including a prominent forehead, telecanthus, depressed nasal bridge, thin upper vermilion and a small chin. Magnetic resonance imaging shows enlargement of the lateral, third and fourth ventricles and hypoplastic corpus callosum, cerebellar vermis and pons. Array CGH revealed a 0.875 Mb de novo deletion at 2p16.1 that includes only BCL11A. The moderate delays, hypoplastic and dysmorphic corpus callosum and hippocampi and the facial features are in keeping with the previously described 2p15-16.1 microdeletion syndrome. However, hypoplasia of the pons and cerebellum are not commonly recognized features and are reminiscent of the brain malformations observed in individuals with a mutation in CASK. CASK is known to interact with BCL11A in the normal growth of axons. This case report highlights the role of BCL11A in 2p15-16.1 microdeletion syndrome and the unique phenotype suggests a common pathway for BCL11A and other genes in neurodevelopment.

Genitourinary defects associated with genomic deletions in 2p15 encompassing OTX1

Normal development of the genitourinary (GU) tract is a complex process that frequently goes awry. In male children the most frequent congenital GU anomalies are cryptorchidism (1-4%), hypospadias (1%) and micropenis (0.35%). Bladder exstrophy and epispadias complex (BEEC) (1∶47000) occurs less frequently but significantly impacts patients' lives. Array comparative genomic hybridization (aCGH) identified seven individuals with overlapping deletions in the 2p15 region (66.0 kb-5.6 Mb). Six of these patients have GU defects, while the remaining patient has no GU defect. These deletions encompass the transcription factor OTX1. Subjects 2-7 had large de novo CNVs (2.39-6.31 Mb) and exhibited features similar to those associated with the 2p15p16.1 and 2p15p14 microdeletion syndromes, including developmental delay, short stature, and variable GU defects. Subject-1 with BEEC had the smallest deletion (66 kb), which deleted only one copy of OTX1. Otx1-null mice have seizures, prepubescent transient growth retardation and gonadal defects. Two subjects have short stature, two have seizures, and six have GU defects, mainly affecting the external genitalia. The presence of GU defects in six patients in our cohort and eight of thirteen patients reported with deletions within 2p14p16.1 (two with deletion of OTX1) suggest that genes in 2p15 are important for GU development. Genitalia defects in these patients could result from the effect of OTX1 on pituitary hormone secretion or on the regulation of SHH signaling, which is crucial for development of the bladder and genitalia.

Haploinsufficiency of XPO1 and USP34 by a de novo 230 kb deletion in 2p15, in a patient with mild intellectual disability and cranio-facial dysmorphisms

2p15p16.1-deletion syndrome was first described in 2007 based on the clinical presentation of two patients. The syndrome is characterized by intellectual disability, autism spectrum disorders, microcephaly, dysmorphic facial features and a variety of congenital organ defects. The precise genotype-phenotype correlation in 2p15-deletion syndrome is not understood. However, greater insight can be obtained by thorough clinical investigation of patients carrying deletions, especially those of small size. We report a 21-year-old male patient with features overlapping the clinical spectrum of the 2p15p16.1-deletion syndrome, such as intellectual disability, dysmorphic facial features, and congenital defects. He carried a 230 kb de novo deletion (chr2:61500346-61733075 bp, hg19), which affects the genes USP34, SNORA70B and XPO1. While there is a lack of functional data on SNORA70B, the involvement of USP34 and XPO1 in the regulation of fundamental developmental processes is well known. We suggest that haploinsufficiency of one or both of these genes is likely to be responsible for the disease in our patient.

De novo microdeletion of BCL11A is associated with severe speech sound disorder

In 10 cases of 2p15p16.1 microdeletions reported worldwide to date, shared phenotypes included growth retardation, craniofacial and skeletal dysmorphic traits, internal organ defects, intellectual disability, nonverbal or low verbal status, abnormal muscle tone, and gross motor delays. The size of the deletions ranged from 0.3 to 5.7 Mb, where the smallest deletion involved the BCL11A, PAPOLG, and REL genes. Here we report on an 11-year-old male with a heterozygous de novo 0.2 Mb deletion containing a single gene, BCL11A, and a phenotype characterized by childhood apraxia of speech and dysarthria in the presence of general oral and gross motor dyspraxia and hypotonia as well as expressive language and mild intellectual delays. BCL11A is situated within the dyslexia susceptibility candidate region 3 (DYX3) candidate region on chromosome 2. The present case is the first to involve a single gene within the microdeletion region and a phenotype restricted to a subset of the traits observed in other cases with more extensive deletions.

Review: the role of vitamin D in nervous system health and disease

Vitamin D and its metabolites have pleomorphic roles in both nervous system health and disease. Animal models have been paramount in contributing to our knowledge and understanding of the consequences of vitamin D deficiency on brain development and its implications for adult psychiatric and neurological diseases. The conflation of in vitro, ex vivo, and animal model data provide compelling evidence that vitamin D has a crucial role in proliferation, differentiation, neurotrophism, neuroprotection, neurotransmission, and neuroplasticity. Vitamin D exerts its biological function not only by influencing cellular processes directly, but also by influencing gene expression through vitamin D response elements. This review highlights the epidemiological, neuropathological, experimental and molecular genetic evidence implicating vitamin D as a candidate in influencing susceptibility to a number of psychiatric and neurological diseases. The strength of evidence varies for schizophrenia, autism, Parkinson's disease, amyotrophic lateral sclerosis, Alzheimer's disease, and is especially strong for multiple sclerosis.

Complex craniosynostosis is associated with the 2p15p16.1 microdeletion syndrome

In a screening project of patients with (complex) craniosynostosis using genomic arrays, we identified two patients with craniosynostosis and microcephaly with a deletion in the 2p15p16.1 chromosomal region. This region has been associated with a new microdeletion syndrome, for which patients have various features in common, including microcephaly and intellectual disability. Deletions were identified using Affymetrix 250K SNP array and further characterized by fluorescence in situ hybridization (FISH) analysis and qPCR. The deletions in our two patients overlapped within the 2p15p16.1 microdeletion syndrome area and were 6.8 and 6.9 Mb in size, respectively. FISH and qPCR confirmed the presence of only one copy in this region. Finemapping of the breakpoints indicated precise borders in our patients and were further finemapped in two other previously reported patients. Clinical features of patients with deletions in the 2p15p16.1 region vary. Including data from our patients, now eight out of nine reported patients have microcephaly, one of the major features, and all had intellectual disability. The current reported two patients add different forms of craniosynostosis to the clinical spectrum of this recently recognized microdeletion syndrome.

Interstitial deletion of chromosome 2p15-16.1: report of two patients and critical review of current genotype-phenotype correlation

We report two individuals with developmental delay and dysmorphic features, in whom array-based comparative genomic hybridization (array CGH) led to the identification of a 2p15p16.1 de novo deletion. In the first patient (Patient 1) a familial deletion of 6q12, inherited from her father, was also detected. In the second patient (Patient 2) in addition to the 2p15p16.1 microdeletion a de novo deletion in Xq28 was detected. Both individuals shared dysmorphic features and developmental delay with the six reported patients with a 2p15p16.1 microdeletion described in medical literature.

CONCLUSION

in the first patient a 642 kb 2p16.1 deletion (from 60.604 to 61.246 Mb), and a 930 kb 6q12 familial deletion, was detected and in the second a 2.5 Mb 2p15p16.1 deletion (from 60.258 to 62.763 Mb), with a Xq28 deletion, was discovered. The common dysmorphic features and neurodevelopmental delay found in these patients are in agreement with the clinical phenotype of a microdeletion syndrome involving 2p15p16.1. Our data confirm the hypothesis suggesting that 2p15p16.1 deletion is a contiguous gene syndrome.

2p15-p16.1 microdeletion syndrome: molecular characterization and association of the OTX1 and XPO1 genes with autism spectrum disorders

Reports of unrelated individuals with autism spectrum disorder (ASD) and similar clinical features having overlapping de novo interstitial deletions at 2p15-p16.1 suggest that this region harbors a gene(s) important to the development of autism. We molecularly characterized two such deletions, selecting two genes in this region, exportin 1 (XPO1) and orthodenticle homolog 1 (OTX1) for association studies in three North American cohorts (Autism Spectrum Disorder - Canadian American Research Consortium (ASD-CARC), New York, and Autism Genetic Resource Exchange (AGRE)) and one Italian cohort (Società Italiana per la Ricerca e la Formazione sull'Autismo (SIRFA)) of families with ASD. In XPO1, rs6735330 was associated with autism in all four cohorts (P<0.05), being significant in ASD-CARC cohorts (P-value following false discovery rate correction for multiple testing (P(FDR))=1.29 × 10(-5)), the AGRE cohort (P(FDR)=0.0011) and the combined families (P(FDR)=2.34 × 10(-9)). Similarly, in OTX1, rs2018650 and rs13000344 were associated with autism in ASD-CARC cohorts (P(FDR)=8.65 × 10(-7) and 6.07 × 10(5), respectively), AGRE cohort (P(FDR)=0.0034 and 0.015, respectively) and the combined families (P(FDR)=2.34 × 10(-9) and 0.00017, respectively); associations were marginal or insignificant in the New York and SIRFA cohorts. A significant association (P(FDR)=2.63 × 10(-11)) was found for the rs2018650G-rs13000344C haplotype. The above three SNPs were associated with severity of social interaction and verbal communication deficits and repetitive behaviors (P-values <0.01). No additional deletions were identified following screening of 798 ASD individuals. Our results indicate that deletion 2p15-p16.1 is not commonly associated with idiopathic ASD, but represents a novel contiguous gene syndrome associated with a constellation of phenotypic features (autism, intellectual disability, craniofacial/CNS dysmorphology), and that XPO1 and OXT1 may contribute to ASD in 2p15-p16.1 deletion cases and non-deletion cases of ASD mapping to this chromosome region.