Familial 22q11.2 duplication: a three-generation family with a 3-Mb duplication and a familial 1.5-Mb duplication

Features and Associated Comorbidities of Laryngomalacia in Saudi Arabia

Laryngomalacia (LM) is defined as the collapse of supraglottic structures during inspiration, resulting in intermittent airflow impedance and associated stridor. LM is the most prevalent cause of congenital stridor in newborns. The aim of this study is to determine the features and associated comorbidities of LM in Saudi Arabia and to delineate the diagnostic and therapeutic measures used, based on the severity of the case and related comorbidities. This is a three-year retrospective study of children diagnosed with LM and treated in the pediatric otorhinolaryngology outpatient clinic at Maternity and Children Hospital, Dammam, Saudi Arabia, between January 2018 and January 2022. The inclusion criteria were patients with signs and symptoms of LM who are younger than 14 years old. The diagnosis of LM was based on clinical evaluation and confirmed by nasopharyngolaryngoscopy in awake patients and/or direct laryngoscopy and scoping under general anesthesia with spontaneous ventilation for dynamic evaluation. The Olney classification was used for the morphological classification of LM. The exclusion criteria were patients lost to follow-ups. Follow-up duration was two years minimum. A total of 52 patients were included in the study. Among the participants, females accounted for 71% and males accounted for 29% of cases. Our results were in accordance with the relevant literature, except for the higher prevalence of LM in full-term neonates who were found to account for 69.2% of the cases. Understanding the patterns and characteristics of breathing may help clinicians distinguish the noisy breathing of LM from other illnesses because infants are frequently misdiagnosed with these conditions.

Identification of a new familial case of 3q29 deletion syndrome associated with cleft lip and palate via whole-exome sequencing

Many unbalanced large copy number variants reviewed in the paper are associated with syndromic orofacial clefts, including a 1.6 Mb deletion on chromosome 3q29. The current report presents a new family with this recurrent deletion identified via whole-exome sequencing and confirmed by array comparative genomic hybridization. The proband exhibited a more severe clinical phenotype than his affected mother, comprising right-sided cleft lip/alveolus and cleft palate, advanced dental caries, heart defect, hypospadias, psychomotor, and speech delay, and an intellectual disability. Data analysis from the 3q29 registry revealed that the 3q29 deletion increases the risk of clefting by nearly 30-fold. No additional rare and pathogenic nucleotide variants were identified that could explain the clefting phenotype and observed intrafamilial phenotypic heterogeneity. These data suggest that the 3q29 deletion may be the primary risk factor for clefting, with additional genomic variants located outside the coding sequences, methylation changes, or environmental exposure serving as modifiers of this risk. Additional studies, including whole-genome sequencing or methylation analyses, should be performed to identify genetic factors underlying the phenotypic variation associated with the recurrent 3q29 deletion.

22q11.2 duplications: Expanding the clinical presentation

22q11.2 duplication syndrome has a frequency of ~1/700 in the intellectual disability population. Despite this frequency, there is limited information on the variable clinical presentation. Although the phenotype and incidence of congenital anomalies are well described for 22q11.2 deletion syndrome, they are not as well understood for individuals with 22q11.2 duplication syndrome. This study is a single-center, retrospective review of patients diagnosed with 22q11.2 duplication syndrome designed to categorize the variable phenotype seen in these individuals. The data suggest that the incidence of congenital anomalies may be higher than previously reported for this syndrome. Affected individuals are at increased risk for a variety of problems including gastrointestinal complications, endocrine dysfunction, ophthalmologic abnormalities, palatal anomalies, congenital heart disease, musculoskeletal differences, and neurologic abnormalities. Individuals with 22q11.2 duplication syndrome would benefit from care coordinated by a multidisciplinary team and managed according to the 22q11.2 deletion syndrome guidelines.

An Unexpected Cause of Ptosis: 22q11.2 Duplication Syndrome

The chromosome 22q11.2 region is highly susceptible to both microdeletions and microduplications that have been known to be responsible for multiple congenital anomaly disorders. We describe a patient of 22q11.2 duplication syndrome presenting with bilateral ptosis who has normal psychomotor development. Cranial magnetic resonance imaging and electromyography with repetitive nerve stimulation were normal. Chromosome microarray analysis was performed, and the patient was found to have a de novo 2.8 Mb duplication at 22q11.21. To our knowledge, bilateral ptosis and normal psychomotor development with 22q11.2 duplication syndrome has not been described. The 22q11.2 duplication syndrome should be considered in the differential diagnosis of ptosis. This case report contributes to an expanding clinical spectrum of patients with 22q11.2 duplication syndrome.

Reciprocal Copy Number Variations at 22q11.2 Produce Distinct and Convergent Neurobehavioral Impairments Relevant for Schizophrenia and Autism Spectrum Disorder

BACKGROUND

22q11.2 deletions and duplications are copy number variations (CNVs) that predispose to developmental neuropsychiatric disorders. Both CNVs are associated with autism spectrum disorder (ASD), while the deletion confers disproportionate risk for schizophrenia. Neurobehavioral profiles associated with these reciprocal CNVs in conjunction with brain imaging measures have not been reported.

METHODS

We profiled the impact of 22q11.2 CNVs on neurobehavioral measures relevant to ASD and psychosis in 106 22q11.2 deletion carriers, 38 22q11.2 duplication carriers, and 82 demographically matched healthy control subjects. To determine whether brain-behavior relationships were altered in CNV carriers, we further tested for interactions between group and regional brain structure on neurobehavioral domains.

RESULTS

Cognitive deficits were observed in both CNV groups, with the lowest IQs in deletion carriers. ASD and dimensionally measured ASD traits were elevated in both CNV groups; however, duplication carriers exhibited increased stereotypies compared to deletion carriers. Moreover, discriminant analysis using ASD subdomains distinguished between CNV cases with 76% accuracy. Both psychotic disorder diagnosis and dimensionally measured positive and negative symptoms were elevated in deletion carriers. Finally, healthy control subjects showed an inverse relationship between processing speed and cortical thickness in heteromodal association areas, which was absent in both CNV groups.

CONCLUSIONS

22q11.2 CNVs differentially modulate intellectual functioning and psychosis-related symptomatology but converge on broad ASD-related symptomatology. However, subtle differences in ASD profiles distinguish CNV groups. Processing speed impairments, coupled with the lack of normative relationship between processing speed and cortical thickness in CNV carriers, implicate aberrant development of the cortical mantle in the pathology underlying impaired processing speed ability.

Congenital nephrotic syndrome associated with 22q11.2 duplication syndrome in a Chinese family and functional analysis of the intronic NPHS1 c. 3286 + 5G > A mutation

Background

Congenital nephrotic syndrome (CNS), which is defined as heavy proteinuria, hypoalbuminemia, hyperlipidemia and edema, is most caused by monogenic defects in structural proteins of the glomerular filtration barrier in the kidneys. 22q11.2 duplication syndrome was a chromosomal disease with variable clinical featuresranging from normal to mental retardation and with congenital defects. Co-occurrence of two genetic disorders in a single patient is rare.

Case presentation

The proband was born at 36 weeks of gestational age spontaneously and weighed 2350 g at birth. Six days after birth, the proband was admitted to our hospital due to fever of 38.5 °C lasting for 6 h. Physical examination at admission time showed dysmorphic features of hypertelorism, palpebral edema, broad nose bridge, upturned nose, dysmorphic auricle, long philtrum, and a thin upper lip. Additionally, we found left wrist drop and bilateral strephexopodia, bilateral knee joint flexion contracture in this patient. A series of indicators were detected and showed abnormalities. Albumin was used to remit the hypoproteinemia and edema. However, the parents refused to accept further therapy and the boy died at age 3 months due to cachexy. To confirm the pathogenesis, genetic analysis were performed and revealed two mutations of NPHS1 gene: Exon18: c.2386G > C; p. (Gly796Arg) inherited from mother, and intron24: c.3286 + 5G > A; p.? inherited from father. And he also had a 22q11.2 duplication which was inherited from his mild affected mother. The pathogenesis of the intronic mutation has been further identified that it can defect alternative splicing of NPHS1.

Conclusions

We present a patient who was caught in congenital nephrotic syndrome and 22q11.2 duplication syndrome simultaneously, emphasizing the importance of new sequencing technology on diagnosis of different genetic disorders.

Modeling and Predicting Developmental Trajectories of Neuropsychiatric Dimensions Associated With Copy Number Variations

Copy number variants, such as duplications and hemizygous deletions at chromosomal loci of up to a few million base pairs, are highly associated with psychiatric disorders. Hemizygous deletions at human chromosome 22q11.2 were found to be associated with elevated instances of schizophrenia and autism spectrum disorder in 1992 and 2002, respectively. Following these discoveries, many mouse models have been developed and tested to analyze the effects of gene dose alterations in small chromosomal segments and single genes of 22q11.2. Despite several limitations to modeling mental illness in mice, mouse models have identified several genes on 22q11.2-Tbx1, Dgcr8, Comt, Sept5, and Prodh-that contribute to dimensions of autism spectrum disorder and schizophrenia, including working memory, social communication and interaction, and sensorimotor gating. Mouse studies have identified that heterozygous deletion of Tbx1 results in defective social communication during the neonatal period and social interaction deficits during adolescence/adulthood. Overexpression of Tbx1 or Comt in adult neural progenitor cells in the hippocampus delays the developmental maturation of working memory capacity. Collectively, mouse models of variants of these 4 genes have revealed several potential neuronal mechanisms underlying various aspects of psychiatric disorders, including adult neurogenesis, microRNA processing, catecholamine metabolism, and synaptic transmission. The validity of the mouse data would be ultimately tested when therapies or drugs based on such potential mechanisms are applied to humans.

Chromosomal Microarray Analysis in Children with Unexplained Developmental Delay/Intellectual Disability

Chromosomal microarray (CMA) analysis for discovery of copy number variants (CNVs) is now recommended as a first-line diagnostic tool in patients with unexplained developmental delay/intellectual disability (DD/ID) and autism spectrum disorders. In this study, we present the results of CMA analysis in patients with DD/ID. Of 210 patients, pathogenic CNVs were detected in 26 (12%) and variants of uncertain clinical significance in 36 (17%) children. The diagnosis of well-recognized genetic syndromes was achieved in 12 patients. CMA analysis revealed pathogenic de novo CNVs, such as 11p13 duplication with new clinical features. Our results support the utility of CMA as a routine diagnostic test for unexplained DD/ID.

Detection of an Underlying 22q11.2 Duplication in a Female Neonate With Trisomy 18

Current guidelines indicate that in patients with developmental disabilities or congenital anomalies, chromosomal microarray (CMA) is a first-tier diagnostic test. However, for patients with obvious chromosomal syndromes such as trisomy 13, 18, and 21, G-banded karyotyping is still recommended over CMA for establishing a diagnosis. In the case presented herein, a female neonate was suspected of having trisomy 18 based on pre- and postnatal evaluations. Karyotyping was requested but not performed due to insufficient cell growth; Interphase fluorescence in situ hybridization (i-FISH) found an extra copy of chromosome 18. CMA analysis uncovered gain of chromosome 18 and an additional duplication in chromosome 22q11.2, which went undetected with FISH. Our patient died within 40 hours after birth, but it is expected that patients with recognizable chromosomal syndromes could benefit from the discovery of coexisting copy number variations (CNVs) using CMA. This case shows that CMA can be a useful test for patients with recognizable chromosomal syndromes because of the potential benefits for patients and their families when co-existing CNVs are found.

Mapping 22q11.2 Gene Dosage Effects on Brain Morphometry

Reciprocal chromosomal rearrangements at the 22q11.2 locus are associated with elevated risk of neurodevelopmental disorders. The 22q11.2 deletion confers the highest known genetic risk for schizophrenia, but a duplication in the same region is strongly associated with autism and is less common in schizophrenia cases than in the general population. Here we conducted the first study of 22q11.2 gene dosage effects on brain structure in a sample of 143 human subjects: 66 with 22q11.2 deletions (22q-del; 32 males), 21 with 22q11.2 duplications (22q-dup; 14 males), and 56 age- and sex-matched controls (31 males). 22q11.2 gene dosage varied positively with intracranial volume, gray and white matter volume, and cortical surface area (deletion < control < duplication). In contrast, gene dosage varied negatively with mean cortical thickness (deletion > control > duplication). Widespread differences were observed for cortical surface area with more localized effects on cortical thickness. These diametric patterns extended into subcortical regions: 22q-dup carriers had a significantly larger right hippocampus, on average, but lower right caudate and corpus callosum volume, relative to 22q-del carriers. Novel subcortical shape analysis revealed greater radial distance (thickness) of the right amygdala and left thalamus, and localized increases and decreases in subregions of the caudate, putamen, and hippocampus in 22q-dup relative to 22q-del carriers. This study provides the first evidence that 22q11.2 is a genomic region associated with gene-dose-dependent brain phenotypes. Pervasive effects on cortical surface area imply that this copy number variant affects brain structure early in the course of development.SIGNIFICANCE STATEMENT Probing naturally occurring reciprocal copy number variation in the genome may help us understand mechanisms underlying deviations from typical brain and cognitive development. The 22q11.2 genomic region is particularly susceptible to chromosomal rearrangements and contains many genes crucial for neuronal development and migration. Not surprisingly, reciprocal genomic imbalances at this locus confer some of the highest known genetic risks for developmental neuropsychiatric disorders. Here we provide the first evidence that brain morphology differs meaningfully as a function of reciprocal genomic variation at the 22q11.2 locus. Cortical thickness and surface area were affected in opposite directions with more widespread effects of gene dosage on cortical surface area.

22q11.2 microduplication syndrome with associated esophageal atresia/tracheo-esophageal fistula and vascular ring

This case report describes a patient with a 22q11.2 duplication. His features, which include VACTERL association with an esophageal atresia/tracheo‐esophageal fistula and a vascular ring, expand the previously described phenotype for this duplication.

Pachygyria, seizures, hypotonia, and growth retardation in a patient with an atypical 1.33Mb inherited microduplication at 22q11.23

22q11.2 microduplication syndrome was recently described as a new disorder with variable clinical features that ranged from normal to mental retardation and with congenital defects. According to published reports, majority of patients with 22q11.2 duplications inherit these from unaffected parents rather than by de novo mutations, which is different from most microduplication/microdeletion syndromes. In this study, we report a patient that carried a paternally inherited atypical 1.33Mb duplication at 22q11.23. The proband (or proposita) presented with hypotonia, feeding difficulties, intractable epilepsy, hearing disability, and pachygyria. A pachygyria phenotype had not been previously reported to be associated with a 22q11 microduplication syndrome. Cytogenetic and molecular genetic analyses based on standard G-banding, SNP array, and fluorescence in situ hybridization were performed for the proband and her parents. An atypical 1.33Mb duplication at 22q11.23 was detected in both the proband and her father. Thus, our findings verify the pathogenicity and diverse phenotypes of 22q11.2 microduplication and expand its phenotypic spectrum.

22q11.2 Microduplication with thyroid hemiagenesis

BACKGROUND

Chromosome 22q11.2 microduplications are extremely rarely detected; in comparison, the deletion of same region, known as the DiGeorge/velocardiofacial syndrome, occurs more frequently. Thyroid anomalies commonly occur in patients with 22q11.2 deletion syndrome, however few reports of thyroid anomalies associated with 22q11.2 microduplication have been published thus far.

CASE REPORT

We present a case of a male infant who was prenatally diagnosed with 22q11.2 microduplication and was found to have congenital hypothyroidism due to thyroid hemiagenesis after birth. Moreover, the baby had bilateral hearing impairment, bilateral cryptorchidism, and a rotated penis. At the age of 2 years, the infant was euthyroid with levothyroxine replacement, but he showed significant developmental delay.

CONCLUSIONS

To our knowledge, this is the first case of congenital hypothyroidism with thyroid hemiagenesis in a patient showing 22q11.2 microduplication. Thyroid dysgenesis could be an additional clinical feature shared by the 22q11.2 microduplication and deletion syndrome, suggesting that the duplication and deletion of a gene may result in a common phenotype. Thyroid dysgenesis should be considered in the evaluation and management of patients with this genomic disorder.

Copy number variation at 22q11.2: from rare variants to common mechanisms of developmental neuropsychiatric disorders

Recently discovered genome-wide rare copy number variants (CNVs) have unprecedented levels of statistical association with many developmental neuropsychiatric disorders, including schizophrenia, autism spectrum disorders, intellectual disability and attention deficit hyperactivity disorder. However, as CNVs often include multiple genes, causal genes responsible for CNV-associated diagnoses and traits are still poorly understood. Mouse models of CNVs are in use to delve into the precise mechanisms through which CNVs contribute to disorders and associated traits. Based on human and mouse model studies on rare CNVs within human chromosome 22q11.2, we propose that alterations of a distinct set of multiple, noncontiguous genes encoded in this chromosomal region, in concert with modulatory impacts of genetic background and environmental factors, variably shift the probabilities of phenotypes along a predetermined developmental trajectory. This model can be further extended to the study of other CNVs and may serve as a guide to help characterize the impact of genes in developmental neuropsychiatric disorders.

Phenotypic heterogeneity in a family with a small atypical microduplication of chromosome 22q11.2 involving TBX1

The chromosome 22q11.2 region is commonly involved in non-allelic homologous recombination (NAHR) events. Microduplications of 22q11.2, usually involving a 3 Mb or 1.5 Mb region constitute the 22q11 microduplication syndrome. Both microdeletions and microduplications of 22q11.21 are reported to share several phenotypic characteristics, including dysmorphic facial features, velopharyngeal insufficiency, congenital heart disease, urogenital abnormalities, and immunologic defects. We report a child who presented at 8 months of age for evaluation of microcephaly and mild motor delay. Head circumference at birth, at 8 months, and at 19 months of age was below the 3rd centile. Other findings included left-sided cryptorchidism and developmental dysplasia of the left hip. In addition, echocardiography revealed a restrictive patent ductus arteriosus. Chromosomal microarray analysis using Affymetrix Genome-Wide Human SNP Array 6.0 revealed a novel 437 kb interstitial duplication at 22q11.21, involving TBX1, whose breakpoints did not coincide with known low copy repeat (LCR) regions. The same duplication was confirmed by fluorescent in situ hybridization (FISH) in the patient's mother and an older sister. The mother has a history of anxiety disorder and depression. The sister had a history of delayed motor milestones. None of the three duplication carriers has any documented renal anomalies or other significant medical problems. This report demonstrates the clinical heterogeneity associated with microduplications of 22q11.2 and illustrates the difficulties related to providing prognostic information and accurate genetic counseling to families when this finding is detected. The described microduplication is the smallest in this genomic region reported to date and further implicates abnormal gene dosage of TBX1 in disorders resulting from 22q11.2 rearrangements.

Laryngomalacia: disease presentation, spectrum, and management

Laryngomalacia is the most common cause of stridor in newborns, affecting 45–75% of all infants with congenital stridor. The spectrum of disease presentation, progression, and outcomes is varied. Identifying symptoms and patient factors that influence disease severity helps predict outcomes. Findings. Infants with stridor who do not have significant feeding-related symptoms can be managed expectantly without intervention. Infants with stridor and feeding-related symptoms benefit from acid suppression treatment. Those with additional symptoms of aspiration, failure to thrive, and consequences of airway obstruction and hypoxia require surgical intervention. The presence of an additional level of airway obstruction worsens symptoms and has a 4.5x risk of requiring surgical intervention, usually supraglottoplasty. The presence of medical comorbidities predicts worse symptoms. Summary. Most with laryngomalacia will have mild-to-moderate symptoms and not require surgical intervention. Those with gastroesophageal reflux and/or laryngopharyngeal reflux have symptom improvement from acid suppression therapy. Those with severe enough disease to require supraglottoplasty will have minimal complications and good outcomes if multiple medical comorbidities are not present. Identifying patient factors that influence disease severity is an important aspect of care provided to infants with laryngomalacia.

Chromosome 22q11.2 duplication is rare in a population-based cohort of Danish children with cardiovascular malformations

The prevalence of the 22q11.2 duplication is unknown in children with cardiovascular malformations (CVMs). As most individuals with the duplication are detected in the search for other conditions, especially the 22q11.2 deletion, CVMs associated with the duplication are subject to referral bias. We circumvented this bias by investigating the prevalence of the 22q11.2 duplication in a population-based cohort of children with CVMs. The study population was defined as children born in 2000-2008, who were registered in the Danish National Patient Registry with a diagnosis of CVM from one of the two national university departments of pediatric cardiology. Sensitive multiplex ligation-dependent probe amplification was performed on dried blood spot samples from each individual's neonatal screening test. The study population consisted of 2,952 children with CVMs, 2,424 of whom were eligible for genetic testing; 13 individuals (0.5% [0.3-0.9%]) carried the duplication. Nine individuals (69%) had not previously been tested for a copy number variation on chromosome 22q11.2 in the clinical setting for children with CVMs. We conclude that 22q11.2 duplication is rare in children with CVMs, and is primarily found in malformations that are also associated with the 22q11.2 deletion.

Evidence for involvement of GNB1L in autism

Structural variations in the chromosome 22q11.2 region mediated by nonallelic homologous recombination result in 22q11.2 deletion (del22q11.2) and 22q11.2 duplication (dup22q11.2) syndromes. The majority of del22q11.2 cases have facial and cardiac malformations, immunologic impairments, specific cognitive profile and increased risk for schizophrenia and autism spectrum disorders (ASDs). The phenotype of dup22q11.2 is frequently without physical features but includes the spectrum of neurocognitive abnormalities. Although there is substantial evidence that haploinsufficiency for TBX1 plays a role in the physical features of del22q11.2, it is not known which gene(s) in the critical 1.5 Mb region are responsible for the observed spectrum of behavioral phenotypes. We identified an individual with a balanced translocation 46,XY,t(1;22)(p36.1;q11.2) and a behavioral phenotype characterized by cognitive impairment, autism, and schizophrenia in the absence of congenital malformations. Using somatic cell hybrids and comparative genomic hybridization (CGH) we mapped the chromosome-22 breakpoint within intron 7 of the GNB1L gene. Copy number evaluations and direct DNA sequencing of GNB1L in 271 schizophrenia and 513 autism cases revealed dup22q11.2 in two families with autism and private GNB1L missense variants in conserved residues in three families (P = 0.036). The identified missense variants affect residues in the WD40 repeat domains and are predicted to have deleterious effects on the protein. Prior studies provided evidence that GNB1L may have a role in schizophrenia. Our findings support involvement of GNB1L in ASDs as well.

Mouse Models of 22q11.2-Associated Autism Spectrum Disorder

Copy number variation (CNV) of human chromosome 22q11.2 is associated with an elevated rate of autism spectrum disorder (ASD) and represents one of syndromic ASDs with rare genetic variants. However, the precise genetic basis of this association remains unclear due to its relatively large hemizygous and duplication region, including more than 30 genes. Previous studies using genetic mouse models suggested that although not all 22q11.2 genes contribute to ASD symptomatology, more than one 22q11.2 genes have distinct phenotypic targets for ASD symptoms. Our data show that deficiency of the two 22q11.2 genesTbx1 and Sept5 causes distinct phenotypic sets of ASD symptoms.

Phenotypic variability of distal 22q11.2 copy number abnormalities

The availability of microarray technology has led to the recent recognition of copy number abnormalities of distal chromosome 22q11.2 that are distinct from the better-characterized deletions and duplications of the proximal region. This report describes five unrelated individuals with copy number abnormalities affecting distal chromosome 22q11.2. We report on novel phenotypic features including diaphragmatic hernia and uterine didelphys associated with the distal microdeletion syndrome; and frontomedial polymicrogyria and callosal agenesis associated with the distal microduplication syndrome. We describe the third distal chromosome 22q11.2 microdeletion patient with Goldenhar syndrome. Patients with distal chromosome 22q11.2 copy number abnormalities exhibit inter- and intra-familial phenotypic variability, and challenge our ability to draw meaningful genotype-phenotype correlations.

Sixteen New Cases Contributing to the Characterization of Patients with Distal 22q11.2 Microduplications

The chromosome region 22q11.2 has long been recognized to be susceptible to genomic rearrangement. More recently, this genomic instability has been shown to extend distally (involving LCR22E-H) to the commonly deleted/duplicated region. To date, 21 index cases with 'distal' 22q11.2 duplications have been reported. We report on the clinical and molecular characterization of 16 individuals with distal 22q11.2 duplications identified by DNA microarray analysis. Two of the individuals have been partly described previously. The clinical phenotype varied among the patients in this study, although the majority displayed various degrees of developmental delay and speech disturbances. Other clinical features included behavioral problems, hypotonia, and dysmorphic facial features. Notably, none of the patients was diagnosed with a congenital heart defect. We found a high degree of inherited duplications. Additional copy number changes of unclear clinical significance were identified in 5 of our patients, and it is possible that these may contribute to the phenotypic expression in these patients as has been suggested recently in a 2-hit 'digenic' model for 16p12.1 deletions. The varied phenotypic expression and incomplete penetrance observed for distal 22q11.2 duplications makes it exceedingly difficult to ascribe pathogenicity for these duplications. Given the observed enrichment of the duplication in patient samples versus healthy controls, it is likely that distal 22q11.2 duplications represent a susceptibility/risk locus for speech and mild developmental delay.

22q11.2 microduplication in a family with recurrent fetal congenital heart disease

People carrying a 22q11.2 microduplication display a phenotype varying from normal to severely affected. We report a phenotypically normal female presented with a fetus having a severe congenital heart defect with ventricular septal defect, tricuspid atresia, patent ductus arteriosus and interrupted aortic arch. The pregnant woman had a history of overall three consecutive aberrant pregnancies with tetralogy of Fallot. Standard G-banding karyotype analysis of the parents and the actual pregnancy were normal, while array comparative genomic hybridization (arrayCGH) analysis revealed a 22q11.2 microduplication within the fetus' genome. Fluorescence in situ hybridization (FISH) and short tandem repeat polymorphism (STRP) tests indicated the affected fetus inherited the interstitial 22q11.2 microduplication from the mother. High-resolution oligonucleotide microarray analysis showed this microduplication is located in the common 3 Mb 22q11.2 deletion region between positions 17.298 Mb and 20.246 Mb with a length of 2.948 Mb. This report demonstrates the remarkable intrafamilial variability of a 22q11.2 microduplication phenotype. The 22q11.2 microduplication carried by one of the healthy parents has most likely contributed to the recurrent fetal heart defects.

Common recurrent microduplication syndromes: diagnosis and management in clinical practice

Details on the phenotypic consequences of genomic microdeletions and microduplications are rapidly emerging in the wake of increased utilization of high-resolution methods for the detection of genomic copy number variants (CNVs). Due to their recent discovery, the complete phenotypic characterization of these syndromes is still in progress. For practicing clinicians, this unprecedented molecular diagnostic capability has in many cases outpaced our ability to convey conclusive information regarding these conditions to patients and family members. In particular, genomic microduplication syndromes are frequently associated with variable phenotypes and incomplete penetrance, leading to difficulty in counseling regarding the potential future consequences of a given microduplication. In this review, we have attempted to provide an initial set of recommendations for the management of patients with recurrent microduplication syndromes. We summarize the clinical information for microduplications of 14 different genomic regions and provide a framework for clinical evaluation and anticipatory guidance in these conditions. It is our expectation that these preliminary guidelines will be revised further for each microduplication syndrome as more information becomes available.

Over-expression of a human chromosome 22q11.2 segment including TXNRD2, COMT and ARVCF developmentally affects incentive learning and working memory in mice

Duplication of human chromosome 22q11.2 is associated with elevated rates of mental retardation, autism and many other behavioral phenotypes. However, because duplications cover 1.5-6 Mb, the precise manner in which segments of 22q11.2 causally affect behavior is not known in humans. We have now determined the developmental impact of over-expression of an approximately 190 kb segment of human 22q11.2, which includes the genes TXNRD2, COMT and ARVCF, on behaviors in bacterial artificial chromosome (BAC) transgenic (TG) mice. BAC TG mice and wild-type (WT) mice were tested for their cognitive capacities, affect- and stress-related behaviors and motor activity at 1 and 2 months of age. An enzymatic assay determined the impact of BAC over-expression on the activity level of COMT. BAC TG mice approached a rewarded goal faster (i.e. incentive learning), but were impaired in delayed rewarded alternation during development. In contrast, BAC TG and WT mice were indistinguishable in rewarded alternation without delays, spontaneous alternation, prepulse inhibition, social interaction, anxiety-, stress- and fear-related behaviors and motor activity. Compared with WT mice, BAC TG mice had an approximately 2-fold higher level of COMT activity in the prefrontal cortex, striatum and hippocampus. These data suggest that over-expression of this 22q11.2 segment enhances incentive learning and impairs the prolonged maintenance of working memory, but has no apparent effect on working memory per se, affect- and stress-related behaviors or motor capacity. High copy numbers of this 22q11.2 segment might contribute to a highly selective set of phenotypes in learning and cognition during development.

A deletion and a duplication in distal 22q11.2 deletion syndrome region. Clinical implications and review

Background

Individuals affected with DiGeorge and Velocardiofacial syndromes present with both phenotypic diversity and variable expressivity. The most frequent clinical features include conotruncal congenital heart defects, velopharyngeal insufficiency, hypocalcemia and a characteristic craniofacial dysmorphism. The etiology in most patients is a 3 Mb recurrent deletion in region 22q11.2. However, cases of infrequent deletions and duplications with different sizes and locations have also been reported, generally with a milder, slightly different phenotype for duplications but with no clear genotype-phenotype correlation to date.

Methods

We present a 7 month-old male patient with surgically corrected ASD and multiple VSDs, and dysmorphic facial features not clearly suggestive of 22q11.2 deletion syndrome, and a newborn male infant with cleft lip and palate and upslanting palpebral fissures. Karyotype, FISH, MLPA, microsatellite markers segregation studies and SNP genotyping by array-CGH were performed in both patients and parents.

Results

Karyotype and FISH with probe N25 were normal for both patients. MLPA analysis detected a partial de novo 1.1 Mb deletion in one patient and a novel partial familial 0.4 Mb duplication in the other. Both of these alterations were located at a distal position within the commonly deleted region in 22q11.2. These rearrangements were confirmed and accurately characterized by microsatellite marker segregation studies and SNP array genotyping.

Conclusion

The phenotypic diversity found for deletions and duplications supports a lack of genotype-phenotype correlation in the vicinity of the LCRC-LCRD interval of the 22q11.2 chromosomal region, whereas the high presence of duplications in normal individuals supports their role as polymorphisms. We suggest that any hypothetical correlation between the clinical phenotype and the size and location of these alterations may be masked by other genetic and/or epigenetic modifying factors.

Polymicrogyria in a child with inv dup del(9p) and 22q11.2 microduplication

Polymicrogyria (PMG) is a relatively common malformation of the cortex for which the pathogenesis remains poorly understood. Both acquired and genetic causes are known, and to date more than 70 cases of PMG have been associated with chromosomal abnormalities. Here we report on a 12-year-old girl presenting with asymmetrical PMG predominantly affecting the right occipital lobe. She was the only child of consanguineous parents. At 7 years of age she was referred for mental retardation with speech delay and seizures. Cytogenetic studies of the patient revealed an inverted 9p duplication/deletion and bacterial artificial chromosomes (BACs)-array also showed a 22q11.2 microduplication confirmed by quantitative PCR. This case is of interest in the search for candidate genes and emphasizes the importance of the 22q11 region in PMG. It also highlights the efficiency of BACs-array in detecting complex rearrangements.

Microduplication 22q11.2: a new chromosomal syndrome

The chromosome 22q11.2 region has long been implicated in genomic diseases. The low-copy repeats spanning the region predispose to homologous recombination events, and mediate nonallelic homologous recombinations that result in rearrangements of 22q11.2. Chromosome duplication of the region that is deleted in patients with DGS/VCFS has been reported, establishing a new genomic duplication syndrome complementary to the 22q11.2 deletion syndrome. Recent data suggest that the frequency of the microduplications 22q11.2 is approximately half that of the deletions. Up till now about 50 unrelated cases of 22q11.2 duplications have been reported. A high frequency of familial duplications has been reported. The phenotype of patients is extremely variable, ranging from multiple defects to mild learning difficulties, sharing features with DGS/VCFS, including heart defects, urogenital abnormalities, velopharyngeal insufficiency with or without cleft palate, and with some individuals being essentially normal. The basis of phenotype variability remains to be elucidated. The large majority of affected individuals have identical 3Mb duplications. The 22q11.2 microduplication syndrome can be diagnosed with high accuracy by interphase fluorescence in situ hybridization, and several other molecular laboratory techniques. The 3Mb duplication encompasses a region containing 40 genes including the TBX1 gene that has been shown to be the major disease gene responsible for the DGS/VCFS. Interestingly, TBX1 gain-of-function mutations, resulting in the same phenotypic spectrum as haploinsufficiency caused by loss-of-function mutations or deletions, have been observed, confirming that TBX1 overexpression might be responsible for the dup22q11.2 disorder.

Unambiguous molecular detections with multiple genetic approach for the complicated chromosome 22q11 deletion syndrome

Background

Chromosome 22q11 deletion syndrome (22q11DS) causes a developmental disorder during the embryonic stage, usually because of hemizygous deletions. The clinical pictures of patients with 22q11DS vary because of polymorphisms: on average, approximately 93% of affected individuals have a de novo deletion of 22q11, and the rest have inherited the same deletion from a parent. Methods using multiple genetic markers are thus important for the accurate detection of these microdeletions.

Methods

We studied 12 babies suspected to carry 22q11DS and 18 age-matched healthy controls from unrelated Taiwanese families. We determined genomic variance using microarray-based comparative genomic hybridization (array-CGH), quantitative real-time polymerase chain reaction (qPCR) and multiplex ligation-dependent probe amplification (MLPA).

Results

Changes in genomic copy number were significantly associated with clinical manifestations for the classical criteria of 22q11DS using MPLA and qPCR (p < 0.01). An identical deletion was shown in three affected infants by MLPA. These reduced DNA dosages were also obtained partially using array-CGH and confirmed by qPCR but with some differences in deletion size.

Conclusion

Both MLPA and qPCR could produce a clearly defined range of deleted genomic DNA, whereas there must be a deleted genome that is not distinguishable using MLPA. These data demonstrate that such multiple genetic approaches are necessary for the unambiguous molecular detection of these types of complicated genomic syndromes.

Sept5 deficiency exerts pleiotropic influence on affective behaviors and cognitive functions in mice

Deletion or duplication of the human chromosome 22q11.2 is associated with many behavioral traits and neuropsychiatric disorders, including autism spectrum disorders and schizophrenia. However, why phenotypes vary widely among individuals with identical deletions or duplications of 22q11.2 and which specific 22q11.2 genes contribute to these phenotypes are still poorly understood. Previous studies have identified a approximately 200 kb 22q11.2 region that contributes to behavioral phenotypes in mice. We tested the role of Septin 5 (Sept5), a gene encoded in the approximately 200 kb region, in affective behaviors, cognitive capacities and motor activity. To evaluate the impact of genetic backgrounds on behavioral phenotypes of Sept5 deficiency, we used mice on two genetic backgrounds. Our data show that Sept5 deficiency decreased affiliative active social interaction, but this phenotypic expression was influenced by genetic backgrounds. In contrast, Sept5 deficiency decreased anxiety-related behavior, increased prepulse inhibition and delayed acquisition of rewarded goal approach, independent of genetic background. These data suggest that Sept5 deficiency exerts pleiotropic effects on a select set of affective behaviors and cognitive processes and that genetic backgrounds could provide an epistatic influence on phenotypic expression.