-
Nature Reviews. Disease Primers Nov 201522q11.2 deletion syndrome (22q11.2DS) is the most common chromosomal microdeletion disorder, estimated to result mainly from de novo non-homologous meiotic recombination... (Review)
Review
22q11.2 deletion syndrome (22q11.2DS) is the most common chromosomal microdeletion disorder, estimated to result mainly from de novo non-homologous meiotic recombination events occurring in approximately 1 in every 1,000 fetuses. The first description in the English language of the constellation of findings now known to be due to this chromosomal difference was made in the 1960s in children with DiGeorge syndrome, who presented with the clinical triad of immunodeficiency, hypoparathyroidism and congenital heart disease. The syndrome is now known to have a heterogeneous presentation that includes multiple additional congenital anomalies and later-onset conditions, such as palatal, gastrointestinal and renal abnormalities, autoimmune disease, variable cognitive delays, behavioural phenotypes and psychiatric illness - all far extending the original description of DiGeorge syndrome. Management requires a multidisciplinary approach involving paediatrics, general medicine, surgery, psychiatry, psychology, interventional therapies (physical, occupational, speech, language and behavioural) and genetic counselling. Although common, lack of recognition of the condition and/or lack of familiarity with genetic testing methods, together with the wide variability of clinical presentation, delays diagnosis. Early diagnosis, preferably prenatally or neonatally, could improve outcomes, thus stressing the importance of universal screening. Equally important, 22q11.2DS has become a model for understanding rare and frequent congenital anomalies, medical conditions, psychiatric and developmental disorders, and may provide a platform to better understand these disorders while affording opportunities for translational strategies across the lifespan for both patients with 22q11.2DS and those with these associated features in the general population.
Topics: Abnormalities, Multiple; Child; DiGeorge Syndrome; Genetic Testing; Humans; Infant, Newborn; Patient Care Team
PubMed: 27189754
DOI: 10.1038/nrdp.2015.71 -
Current Allergy and Asthma Reports Apr 2023This review focuses on immunologic findings, relationships among immunologic findings and associated conditions of autoimmunity and atopy, and management of immunologic... (Review)
Review
PURPOSE OF REVIEW
This review focuses on immunologic findings, relationships among immunologic findings and associated conditions of autoimmunity and atopy, and management of immunologic disease in chromosome 22q11.2 deletion syndrome (22q11.2DS, historically known as DiGeorge syndrome).
RECENT FINDINGS
The implementation of assessment of T cell receptor excision circles (TRECs) in newborn screening has led to increased detection of 22q11.2 deletion syndrome. While not yet applied in clinical practice, cell-free DNA screening for 22q11.2DS also has the potential to improve early detection, which may benefit prompt evaluation and management. Multiple studies have further elucidated phenotypic features and potential biomarkers associated with immunologic outcomes, including the development of autoimmune disease and atopy. The clinical presentation of 22q11.2DS is highly variable particularly with respect to immunologic manifestations. Time to recovery of immune system abnormalities is not well-defined in current literature. An understanding of the underlying causes of immunologic changes found in 22q11.2DS, and the progression and evolution of immunologic changes over the lifespan have expanded over time and with improved survival. An included case highlights the variability of presentation and potential severity of T cell lymphopenia in partial DiGeorge syndrome and demonstrates successful spontaneous immune reconstitution in partial DiGeorge syndrome despite initial severe T cell lymphopenia.
Topics: Infant, Newborn; Humans; DiGeorge Syndrome; Chromosome Deletion; Neonatal Screening; Lymphopenia; Chromosomes
PubMed: 36897497
DOI: 10.1007/s11882-023-01071-4 -
Medicine Jan 2011Chromosome 22q11.2 deletion syndrome is a common syndrome also known as DiGeorge syndrome and velocardiofacial syndrome. It occurs in approximately 1:4000 births, and... (Review)
Review
Chromosome 22q11.2 deletion syndrome is a common syndrome also known as DiGeorge syndrome and velocardiofacial syndrome. It occurs in approximately 1:4000 births, and the incidence is increasing due to affected parents bearing their own affected children. The manifestations of this syndrome cross all medical specialties, and care of the children and adults can be complex. Many patients have a mild to moderate immune deficiency, and the majority of patients have a cardiac anomaly. Additional features include renal anomalies, eye anomalies, hypoparathyroidism, skeletal defects, and developmental delay. Each child's needs must be tailored to his or her specific medical problems, and as the child transitions to adulthood, additional issues will arise. A holistic approach, addressing medical and behavioral needs, can be very helpful.
Topics: Animals; Chromosome Deletion; Chromosomes, Human, Pair 22; DiGeorge Syndrome; Disease Models, Animal; Genotype; Humans; Mice; Phenotype; Prevalence
PubMed: 21200182
DOI: 10.1097/MD.0b013e3182060469 -
American Journal of Medical Genetics.... Oct 2018The 22q11.2 deletion syndrome (22q11.2DS) is a congenital malformation and neuropsychiatric disorder caused by meiotic chromosome rearrangements. One of the goals of... (Review)
Review
The 22q11.2 deletion syndrome (22q11.2DS) is a congenital malformation and neuropsychiatric disorder caused by meiotic chromosome rearrangements. One of the goals of this review is to summarize the current state of basic research studies of 22q11.2DS. It highlights efforts to understand the mechanisms responsible for the 22q11.2 deletion that occurs in meiosis. This mechanism involves the four sets of low copy repeats (LCR22) that are dispersed in the 22q11.2 region and the deletion is mediated by nonallelic homologous recombination events. This review also highlights selected genes mapping to the 22q11.2 region that may contribute to the typical clinical findings associated with the disorder and explain that mutations in genes on the remaining allele can uncover rare recessive conditions. Another important aspect of 22q11.2DS is the existence of phenotypic heterogeneity. While some patients are mildly affected, others have severe medical, cognitive, and/or psychiatric challenges. Variability may be due in part to the presence of genetic modifiers. This review discusses current genome-wide efforts to identify such modifiers that could shed light on molecular pathways required for normal human development, cognition or behavior.
Topics: Abnormalities, Multiple; Chromosome Deletion; Chromosomes, Human, Pair 22; DiGeorge Syndrome; Genes, Recessive; Genetic Testing; Humans; Meiosis; Mutation
PubMed: 30380194
DOI: 10.1002/ajmg.a.40504 -
BMJ Case Reports Feb 2022DiGeorge syndrome (DGS) is caused by a chromosomal microdeletion at 22q11.2 that results in impaired development of the pharyngeal pouch system. Patients with DGS may...
DiGeorge syndrome (DGS) is caused by a chromosomal microdeletion at 22q11.2 that results in impaired development of the pharyngeal pouch system. Patients with DGS may have developmental abnormalities of craniofacial structures, parathyroid glands, thymus and cardiac outflow tract. Doctors have been routinely testing for DGS in newborns with conotruncal cardiac anomalies since the late 1990s; before then, however, they relied on complex diagnostic criteria and the disease was often missed. Adults born with conotruncal defects before the late 1990s may have undiagnosed DGS. We present one such case: a 35-year-old woman with a cardiac diagnosis of tetralogy of Fallot and unilateral absence of a pulmonary arter who was found to have DGS. Identifying DGS in adults is important both for disease management and genetic counselling. Our case emphasises the importance of screening for DGS in adults who were born with conotruncal cardiac abnormalities before widespread neonatal testing became common.
Topics: Adult; Chromosome Deletion; DiGeorge Syndrome; Female; Heart; Heart Defects, Congenital; Humans; Infant, Newborn
PubMed: 35110278
DOI: 10.1136/bcr-2021-245164 -
Genetics in Medicine : Official Journal... Mar 2023This review aimed to update the clinical practice guidelines for managing children and adolescents with 22q11.2 deletion syndrome (22q11.2DS). The 22q11.2 Society, the... (Review)
Review
This review aimed to update the clinical practice guidelines for managing children and adolescents with 22q11.2 deletion syndrome (22q11.2DS). The 22q11.2 Society, the international scientific organization studying chromosome 22q11.2 differences and related conditions, recruited expert clinicians worldwide to revise the original 2011 pediatric clinical practice guidelines in a stepwise process: (1) a systematic literature search (1992-2021), (2) study selection and data extraction by clinical experts from 9 different countries, covering 24 subspecialties, and (3) creation of a draft consensus document based on the literature and expert opinion, which was further shaped by survey results from family support organizations regarding perceived needs. Of 2441 22q11.2DS-relevant publications initially identified, 2344 received full-text reviews, including 1545 meeting criteria for potential relevance to clinical care of children and adolescents. Informed by the available literature, recommendations were formulated. Given evidence base limitations, multidisciplinary recommendations represent consensus statements of good practice for this evolving field. These recommendations provide contemporary guidance for evaluation, surveillance, and management of the many 22q11.2DS-associated physical, cognitive, behavioral, and psychiatric morbidities while addressing important genetic counseling and psychosocial issues.
Topics: Adolescent; Humans; Child; DiGeorge Syndrome; Genetic Counseling; Surveys and Questionnaires
PubMed: 36729053
DOI: 10.1016/j.gim.2022.11.006 -
Cytogenetic and Genome Research 2015Chromosome 22q11.21 contains a cluster of low-copy repeats (LCRs), referred to as LCR22A-H, that mediate meiotic non-allelic homologous recombination, resulting in... (Review)
Review
Chromosome 22q11.21 contains a cluster of low-copy repeats (LCRs), referred to as LCR22A-H, that mediate meiotic non-allelic homologous recombination, resulting in either deletion or duplication of various intervals in the region. The deletion of the DiGeorge/velocardiofacial syndrome interval LCR22A-D is the most common recurrent microdeletion in humans, with an estimated incidence of ∼1:4,000 births. Deletion of other intervals in 22q11.21 have also been described, but the literature is often confusing, as the terms 'proximal', 'nested', 'distal', and 'atypical' have all been used to describe various of the other intervals. Individuals with deletions tend to have features with widely variable expressivity, even among families. This review concisely delineates each interval and classifies the reported literature accordingly.
Topics: Chromosome Deletion; Chromosomes, Human, Pair 22; DNA Copy Number Variations; DiGeorge Syndrome; Gene Duplication; Humans; Models, Genetic; Repetitive Sequences, Nucleic Acid; Sequence Deletion
PubMed: 26278718
DOI: 10.1159/000438708 -
Journal of Clinical Immunology Feb 2023Current practices vary widely regarding the immunological work-up and management of patients affected with defects in thymic development (DTD), which include chromosome... (Review)
Review
Current practices vary widely regarding the immunological work-up and management of patients affected with defects in thymic development (DTD), which include chromosome 22q11.2 microdeletion syndrome (22q11.2del) and other causes of DiGeorge syndrome (DGS) and coloboma, heart defect, atresia choanae, retardation of growth and development, genital hypoplasia, ear anomalies/deafness (CHARGE) syndrome. Practice variations affect the initial and subsequent assessment of immune function, the terminology used to describe the condition and immune status, the accepted criteria for recommending live vaccines, and how often follow-up is needed based on the degree of immune compromise. The lack of consensus and widely varying practices highlight the need to establish updated immunological clinical practice guidelines. These guideline recommendations provide a comprehensive review for immunologists and other clinicians who manage immune aspects of this group of disorders.
Topics: Humans; DiGeorge Syndrome; Chromosome Deletion; CHARGE Syndrome; Chromosomes; Heart Defects, Congenital
PubMed: 36648576
DOI: 10.1007/s10875-022-01418-y -
International Journal of Molecular... May 2023The 22q11.2 deletion syndrome is a multisystemic disorder characterized by a marked variability of phenotypic features, making the diagnosis challenging for clinicians.... (Review)
Review
The 22q11.2 deletion syndrome is a multisystemic disorder characterized by a marked variability of phenotypic features, making the diagnosis challenging for clinicians. The wide spectrum of clinical manifestations includes congenital heart defects-most frequently conotruncal cardiac anomalies-thymic hypoplasia and predominating cellular immune deficiency, laryngeal developmental defects, midline anomalies with cleft palate and velar insufficiency, structural airway defects, facial dysmorphism, parathyroid and thyroid gland hormonal dysfunctions, speech delay, developmental delay, and neurocognitive and psychiatric disorders. Significant progress has been made in understanding the complex molecular genetic etiology of 22q11.2 deletion syndrome underpinning the heterogeneity of clinical manifestations. The deletion is caused by chromosomal rearrangements in meiosis and is mediated by non-allelic homologous recombination events between low copy repeats or segmental duplications in the 22q11.2 region. A range of genetic modifiers and environmental factors, as well as the impact of hemizygosity on the remaining allele, contribute to the intricate genotype-phenotype relationships. This comprehensive review has been aimed at highlighting the molecular genetic background of 22q11.2 deletion syndrome in correlation with a clinical multidisciplinary approach.
Topics: Humans; DiGeorge Syndrome; Chromosome Deletion; Heart Defects, Congenital; Molecular Biology; Chromosomes
PubMed: 37176024
DOI: 10.3390/ijms24098317 -
Genetics in Medicine : Official Journal... Mar 2023This review aimed to update the clinical practice guidelines for managing adults with 22q11.2 deletion syndrome (22q11.2DS). The 22q11.2 Society recruited expert...
This review aimed to update the clinical practice guidelines for managing adults with 22q11.2 deletion syndrome (22q11.2DS). The 22q11.2 Society recruited expert clinicians worldwide to revise the original clinical practice guidelines for adults in a stepwise process according to best practices: (1) a systematic literature search (1992-2021), (2) study selection and synthesis by clinical experts from 8 countries, covering 24 subspecialties, and (3) formulation of consensus recommendations based on the literature and further shaped by patient advocate survey results. Of 2441 22q11.2DS-relevant publications initially identified, 2344 received full-text review, with 2318 meeting inclusion criteria (clinical care relevance to 22q11.2DS) including 894 with potential relevance to adults. The evidence base remains limited. Thus multidisciplinary recommendations represent statements of current best practice for this evolving field, informed by the available literature. These recommendations provide guidance for the recognition, evaluation, surveillance, and management of the many emerging and chronic 22q11.2DS-associated multisystem morbidities relevant to adults. The recommendations also address key genetic counseling and psychosocial considerations for the increasing numbers of adults with this complex condition.
Topics: Adult; Humans; Clinical Relevance; Consensus; DiGeorge Syndrome; Genetic Counseling; Surveys and Questionnaires
PubMed: 36729052
DOI: 10.1016/j.gim.2022.11.012