Complete Sequence of the 22q11.2 Allele in 1,053 Subjects with 22q11.2 Deletion Syndrome Reveals Modifiers of Conotruncal Heart Defects.

The 22q11.2 deletion syndrome (22q11.2DS) results from non-allelic homologous recombination between low-copy repeats termed LCR22. About 60%-70% of individuals with the typical 3 megabase (Mb) deletion from LCR22A-D have congenital heart disease, mostly of the conotruncal type (CTD), whereas others have normal cardiac anatomy. In this study, we tested whether variants in the hemizygous LCR22A-D region are associated with risk for CTDs on the basis of the sequence of the 22q11.2 region from 1,053 22q11.2DS individuals. We found a significant association (FDR p < 0.05) of the CTD subset with 62 common variants in a single linkage disequilibrium (LD) block in a 350 kb interval harboring CRKL. A total of 45 of the 62 variants were associated with increased risk for CTDs (odds ratio [OR) ranges: 1.64-4.75). Associations of four variants were replicated in a meta-analysis of three genome-wide association studies of CTDs in affected individuals without 22q11.2DS. One of the replicated variants, rs178252, is located in an open chromatin region and resides in the double-elite enhancer, GH22J020947, that is predicted to regulate CRKL (CRK-like proto-oncogene, cytoplasmic adaptor) expression. Approximately 23% of patients with nested LCR22C-D deletions have CTDs, and inactivation of Crkl in mice causes CTDs, thus implicating this gene as a modifier. Rs178252 and rs6004160 are expression quantitative trait loci (eQTLs) of CRKL. Furthermore, set-based tests identified an enhancer that is predicted to target CRKL and is significantly associated with CTD risk (GH22J020946, sequence kernal association test (SKAT) p = 7.21 × 10-5) in the 22q11.2DS cohort. These findings suggest that variance in CTD penetrance in the 22q11.2DS population can be explained in part by variants affecting CRKL expression.

Immunologic, Molecular, and Clinical Profile of Patients with Chromosome 22q11.2 Duplications.

PURPOSE: Duplication of chromosome 22q11.2 due to meiotic non-allelic homologous recombination results in a distinct syndrome, chromosome 22q11.2 duplication syndrome that has some overlapping phenotypic features with the corresponding 22q11.2 deletion syndrome. Literature on immunologic aspects of the duplication syndrome is limited. We conducted a retrospective study of 216 patients with this syndrome to better define the key features of the duplication syndrome. METHODS: Single-center retrospective record review was performed. Data regarding demographics, clinical details, and immunological tests were compiled, extracted into a predetermined data collection form, and analyzed. RESULTS: This cohort comprised 113 (52.3%) males and 103 (47.7%) females. The majority (54.6%) of mapped duplications were between low copy repeat regions A-D (LCR22A to -D). Though T cell subsets were relatively preserved, switched memory B cells, immunoglobulins, and specific antibodies were each found to be decreased in a subset of the cohort. One-fifth (17/79, 21.5%) of patients had at least 2 low immunoglobulin values, and panhypogammaglobulinemia was found in 11.7% (9/79) cases. Four children were on regular immunoglobulin replacement therapy. Asthma and eczema were the predominant atopic symptoms in our cohort. CONCLUSION: Significant immunodeficiencies were observed in our cohort, particularly in B cells and antibodies. Our study expands the current clinical understanding and emphasizes the need of immunological studies and multidisciplinary approaches for these patients.

A 22q13.1 duplication in mosaicism including SOX10.

Waardenburg syndrome (WS) is characterized by the association of sensorineural hearing loss and pigmentation abnormalities. Among the four types, WS Type 2 (WS2) is the only one without a remarkable distinguishing feature. Here, we report a patient initially diagnosed with WS2 who exhibits a 446 kb mosaic duplication in chromosome 22q13.1, encompassing SOX10, and detected using whole genome sequencing in a trio. The patient, a 46,XY boy, presents with profound bilateral sensorineural hearing loss, right heterochromia iridium, left bright blue iris, and skin-depigmented areas in the abdomen and limbs. Vestibular and imaging tests are normal, without inner ear or olfactory bulb malformations. Bilateral cochlear implantation did not prevent language and speech delays. Moderate congenital chronic constipation and neurodevelopmental difficulties were also present. Given the few genes included in this duplicated region (only one OMIM gene with dominant inheritance), this report provides further delineation of the phenotype related to duplications encompassing the entire SOX10 gene.

Chromosome 22q11.2 Deletion (DiGeorge Syndrome): Immunologic Features, Diagnosis, and Management.

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.

Clinical and Immunological Defects and Outcomes in Patients with Chromosome 22q11.2 Deletion Syndrome.

BACKGROUND: Chromosome 22q11.2 deletion syndrome (22q11.2DS) is the most common microdeletion syndrome in humans and can present with highly variable clinical manifestations. Immune deficiencies occur because of thymic hypoplasia or aplasia. METHODS: This retrospective study included patients diagnosed with 22q11.2DS at a medical center between 2000 and 2021. We analyzed the association between clinical phenotypes, immunological abnormalities, age, and outcomes. RESULTS: Eighty-seven patients with 22q11.2DS had a median diagnostic age of 1.78 months. Patients presented with congenital heart disease (CHD; 86.2%), major infections (75.9%), and failure to thrive (FTT; 58.6%). Autoimmunity, neuropsychiatric disorders, and hypoparathyroidism were significantly associated. Neonatal seizures were associated with early diagnosis before 2 months (OR 8.56, 95% CI 1.21-60.58, P = 0.032). Immunological abnormalities included lymphopenia (93.1%), T lymphopenia (71.9%), CD4+ T lymphopenia (64.1%), a lack of hepatitis B vaccine antibodies (46.2%), and complete DiGeorge syndrome (cDGS) (2.3%). Severe lymphopenia and T lymphopenia improved at 3 years of age. Two patients with cDGS were treated with hematopoietic stem cell transplantation, and one survived. The mortality rate was 12.8% and the estimated 35-year survival probability was 77.5%. Major infections experienced > four times were significantly associated with a decreased survival rate of 60%. Patients with CHD without FTT or recurrent infections had a better 20-year survival rate (96.2%). CONCLUSIONS: CHD, major infection, and FTT were common manifestations and poor prognostic factors. Autoimmunity, neuropsychiatric disorders, and hypoparathyroidism were significantly associated. Although T lymphopenia may improve with age, patients with 22q11.2DS require lifelong monitoring for immune dysregulation.

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.

Chromatin Modifications in 22q11.2 Deletion Syndrome.

PURPOSE: Chromosome 22q11.2 deletion syndrome is a common inborn error of immunity. The early consequences of thymic hypoplasia are low T cell numbers. Later in life, atopy, autoimmunity, inflammation, and evolving hypogammaglobulinemia can occur and the causes of these features are not understood. This study utilized an unbiased discovery approach to define alterations in histone modifications. Our goal was to identify durable chromatin changes that could influence cell behavior. METHODS: CD4 T cells and CD19 B cells underwent ChIP-seq analysis using antibodies to H3K4me3, H3K27ac, and H4ac. RNA effects were defined in CD4 T cells by RNA-seq. Serum cytokines were examined by Luminex. RESULTS: Histone marks of transcriptional activation at CD4 T cell promoters and enhancers were globally increased. The promoter activation signature had elements related to T cell activation and inflammation, concordant with effects seen in the transcriptome. B cells, in contrast, had a minimally altered epigenetic landscape in 22q11.2. Both cell types had an "edge" effect with markedly altered chromatin adjacent to the deletion. CONCLUSIONS: People with 22q11.2 deletion have altered CD4 T cell chromatin and a transcriptome concordant with the changes in the epigenome. These effects support a disease model where qualitative changes to T cells occur in addition to quantitative defects that have been well characterized. This study offers unique insight into qualitative differences in the T cells in 22q11.2 deletion, an aspect that has received limited attention.

Genotype-phenotype correlation in Phelan-McDermid syndrome: A comprehensive review of chromosome 22q13 deleted genes.

Phelan-McDermid syndrome (PMS, OMIM #606232), also known as chromosome 22q13 deletion syndrome, is a rare genetic disorder characterized by intellectual disability, hypotonia, delayed or absent speech, motor impairment, autism spectrum disorder, behavioral anomalies, and minor aspecific dysmorphic features. Haploinsufficiency of SHANK3, due to intragenic deletions or point mutations, is sufficient to cause many neurobehavioral features of PMS. However, several additional genes located within larger 22q13 deletions can contribute to the great interindividual variability observed in the PMS phenotype. This review summarizes the phenotypic contributions predicted for 213 genes distributed along the largest 22q13.2-q13.33 terminal deletion detected in our sample of 63 PMS patients by array-CGH analysis, spanning 9.08 Mb. Genes have been grouped into four categories: (1) genes causing human diseases with an autosomal dominant mechanism, or (2) with an autosomal recessive mechanism; (3) morphogenetically relevant genes, either involved in human diseases with additive co-dominant, polygenic, and/or multifactorial mechanisms, or implicated in animal models but not yet documented in human pathology; (4) protein coding genes either functionally nonrelevant, with unknown function, or pathogenic through mechanisms other than haploinsufficiency; piRNAs, noncoding RNAs, miRNAs, novel transcripts and pseudogenes. Our aim is to understand genotype-phenotype correlations in PMS patients and to provide clinicians with a conceptual framework to promote evidence-based genetic work-ups, clinical assessments, and therapeutic interventions.

Cardiac evaluation of patients with 22q11.2 duplication syndrome.

The 22q11.2 duplication syndrome (22q11.2DupS) is characterized by phenotypic heterogeneity, from seemingly asymptomatic to severely affected patients. Our study sought to detail the cardiac phenotype associated with 22q11.2DupS, the prevalence of aortic arch anomalies and aortic root dilation in 22q11.2DupS, and to assess how frequently new congenital heart disease (CHD) is diagnosed at outpatient cardiac evaluation following genetic diagnosis. In our cohort of 85 patients, 20.0% had CHD, with a wide range of phenotypes. Sixty-eight patients had complete cardiac evaluations detailing aortic arch sidedness and branching pattern, of which 5 (7.4%) had an aortic arch anomaly, all of whom had concurrent intracardiac CHD. Of 53 patients without CHD who had complete cardiac evaluations, only 3 (5.7%) had evidence of aortic root dilation. Of 46 patients who underwent outpatient cardiac evaluation following diagnosis of 22q11.2DupS, only one (2.2%) was found to have CHD, an isolated bicuspid aortic valve without stenosis. Therefore, the CHD phenotype in 22q11.2DupS, when present, is heterogeneous. Aortic arch anomalies are uncommon, and no patient in our cohort had one in isolation. Isolated aortic root dilation is also uncommon. Finally, outpatient cardiac evaluation following genetic diagnosis without previously known CHD infrequently identified minor cardiac malformations.

Chromosome 22 Deletions and Suicidal Behavior in Schizophrenia.

BACKGROUND: Studies have shown that the overall copy number variant (CNV) load is associated with schizophrenia. Schizophrenia is a mental disorder that is frequently associated with suicidal behavior. METHODS: We recruited 263 patients with schizophrenia from the Centre for Addiction and Mental Health. The Columbia Suicide Severity Rating Scale was used to assess the presence of lifetime suicide attempt. Genotyping was completed using the Illumina Omni 2.5 chip. We tested the association between deletion events on chromosome 22 with suicide attempt in our schizophrenia sample. RESULTS: There was no significant difference between suicide attempters and non-attempters considering the presence/absence of deletion events on chromosome 22. CONCLUSION: Although our results did not show a significant association between deletions on chromosome 22 and suicide attempt in schizophrenia, CNV studies may reveal important, novel insights and open further investigation for the treatment of neuropsychiatric diseases.

Bilateral Vestibular Schwannomas in a Patient with Ring Chromosome 22: Case Report and Review of the Literature.

INTRODUCTION: Ring chromosome 22 (r[22]) can lead to the development of intracranial tumors such as meningiomas, neurofibromas, and schwannomas similar to neurofibromatosis 2 (NF2). CASE PRESENTATION: An 18-year-old female with r(22) and a history of global development delay and cognitive impairment presented with sudden hearing loss. MRI revealed bilateral vestibular schwannomas. Given documented audiologic decline in the patient's hearing, the larger tumor was treated with CyberKnife fractionated stereotactic radiosurgery, and the smaller tumor is being monitored. CONCLUSION: This case provides further evidence that patients with r(22) can develop clinical features of NF2, including the development of bilateral vestibular schwannomas, and should be monitored for hearing disturbances starting in puberty as a warning sign for these tumors.

Genotypic and phenotypic variability of 22q11.2 microduplications: An institutional experience.

Duplications in the 22q11.2 region can cause 22q11.2 duplication syndrome and encompass a variety of phenotypes including developmental delays, facial abnormalities, cardiovascular defects, central nervous system delays, and other congenital abnormalities. However, the contribution of these contiguous duplicated regions to the clinical phenotypes has not been fully elucidated. In this study, we identified nine patients carrying different 22q11.2 microduplications detected by chromosomal microarray. Of these patients, seven pediatric patients presented with various clinical features including two neonate cases died shortly after birth, and two healthy adults. We examined region specific genotype-phenotype associations and found unpredictability associated with 22q11.2 duplications in these nine patients.

Fatal overwhelming postsplenectomy infection due to Streptococcus pneumoniae serotype 10A with atypical polysaccharide capsule in a patient with chromosome 22q11.2 deletion syndrome: A case report.

We report the first case of a teenage patient with chromosome 22q11.2 deletion syndrome who died of overwhelming postsplenectomy infection (OPSI) by Streptococcus pneumoniae despite appropriate prevention by pneumococcal vaccine. He had congenital heart disease and underwent several surgeries. Immunodeficiency had not been noticed clinically. Two years prior to death, splenectomy was performed for a drug-resistant idiopathic thrombocytopenic purpura and he was immunized with 23-valent pneumococcal polysaccharide vaccine (PPV23) 4 months after splenectomy. He died suddenly after a mild flu-like symptom. Autopsy was performed and OPSI was diagnosed. Blood culture was positive for S. pneumoniae. This isolated S. pneumoniae strain was serotypically un-typable by polyvalent serum agglutination test. On the contrary, multilocus sequence typing followed by DNA sequencing indicated the molecular serotype as 10A. Additional testing using monovalent and factor-specific sera confirmed the strain as serotype 10A. Ultrastructural observation of this S. pneumoniae strain showed that the polysaccharide capsule was thin and sparse. We speculate that the abnormal morphology of the capsule may have accounted for the polyvalent serum agglutination failure and may possibly be associated with severity of OPSI observed in this case. Chromosome 22q11.2 deletion syndrome is associated with certain immunodeficiency, especially susceptible to S. pneumoniae infections; however, fatal OPSI has not been reported. In addition to vaccination, prophylactic antibiotics may be necessary for these patients who are at risk of immunodeficiency.

Microdeletion 22q11.2 syndrome: Does thymus incidental surgical resection affect its immunological profile?

BACKGROUND: The del22q11 syndrome patients present immunological abnormalities associated to thymus alterations. Up to 75% of them present cardiopathies and thymus is frequently removed during surgery. The thymectomy per se has a deleterious effect concerning lymphocyte subpopulations, and T cell function. When compared to healthy controls, these patients have higher infections propensity of variable severity. The factors behind these variations are unknown. We compared immunological profiles of del22q11.2 Syndrome patients with and without thymectomy to establish its effect in the immune profile. METHODS: Forty-six del22q11.2 syndrome patients from 1 to 16 years old, 19 of them with partial or total thymectomy were included. Heart disease type, heart surgery, infections events and thymus resection were identified. Immunoglobulin levels, flow cytometry for lymphocytes subpopulations and TREC levels were determined, and statistical analyses were performed. RESULTS: The thymectomy group had a lower lymphocyte index, both regarding total cell count and when comparing age-adjusted Z scores. Also, CD3+, CD4+ and CD8+ lower levels were observed in this group, the lowest count in those patients who had undergone thymus resection during the first year of life. Their TREC level median was 23.6/µL vs 16.1µL in the non-thymus group (p=0.22). No differences were identified regarding immunoglobulin levels or infection events frequencies over the previous year. CONCLUSION: Patients with del22q11.2 syndrome subjected to thymus resection present lower lymphocyte and TREC indexes when compared to patients without thymectomy. This situation may be influenced by the age at the surgery and the time elapsed since the procedure.

Assessment of airway abnormalities in patients with tetralogy of Fallot, pulmonary atresia, and major aortopulmonary collaterals.

BACKGROUND: Children with tetralogy of Fallot, pulmonary atresia, and major aortopulmonary collaterals (TOF/MAPCAs) are at risk for post-operative respiratory complications after undergoing unifocalisation surgery. Thus, we assessed and further defined the incidence of airway abnormalities in our series of over 500 children with TOF/MAPCAs as determined by direct laryngoscopy, chest computed tomography (CT), and/or bronchoscopy. METHODS: The medical records of all patients with TOF/MAPCAs who underwent unifocalisation or pulmonary artery reconstruction surgery from March, 2002 to June, 2018 were reviewed. Anaesthesia records, peri-operative bronchoscopy, and/or chest CT reports were reviewed to assess for diagnoses of abnormal or difficult airway. Associations between chromosomal anomalies and airway abnormalities - difficult anaesthetic airway, bronchoscopy, and/or CT findings - were defined. RESULTS: Of the 564 patients with TOF/MAPCAs who underwent unifocalisation or pulmonary artery reconstruction surgery at our institution, 211 (37%) had a documented chromosome 22q11 microdeletion and 28 (5%) had a difficult airway/intubation reported at the time of surgery. Chest CT and/or peri-operative bronchoscopy were performed in 234 (41%) of these patients. Abnormalities related to malacia or compression were common. In total 35 patients had both CT and bronchoscopy within 3 months of each other, with concordant findings in 32 (91%) and partially concordant findings in the other 3. CONCLUSION: This is the largest series of detailed airway findings (direct laryngoscopy, CT, and bronchoscopy) in TOF/MAPCAS patients. Although these findings are specific to an at-risk population for airway abnormalities, they support the utility of CT and /or bronchoscopy in detecting airway abnormalities in patients with TOF/MAPCAs.

A CRYBB2 mutation in a Taiwanese family with autosomal dominant cataract.

BACKGROUND/PURPOSE: To identify the underlying genetic cause of a Taiwanese family with autosomal dominant cerulean cataract. METHODS: A three-generation cerulean cataract family with 13 affected and 13 normal was identified. Whole exome sequencing, whole genome single nucleotide polymorphism genotyping and haplotype analysis, and fine mapping using polymorphic short tandem repeat markers were used to identify the causative gene mutation. RESULTS: Whole genome single nucleotide polymorphism genotyping and haplotype analysis mapped the candidate disease loci to chromosome 18 and chromosome 22. Polymorphic short tandem repeat markers further narrowed down the disease interval to chromosome 22 between markers D22S1174 and D22S1163. Whole exome sequencing was performed on selected individuals. Polymorphisms detected were filtered based on their genomic positions, allele frequency (<1%), and segregation within the pedigree. Affected individuals were found to be heterozygous carrying a C to T mutation on exon 6 of the CRYBB2 gene (with SNP ID: rs74315489). The mutation was predicted to produce a premature stop mutation Q155X. The mutation is co-segregation across the pedigree and the disease "T" allele was not detected in healthy members of the family and in additional 50 normal controls (100 chromosomes). Phylogenic protein alignment was also performed for the CRYBB2 gene across 68 species ranging from fishes, Sauropsida, Placentalia, carnivores, rodents, and primates with total 56 orthologous genes. The Q155 residue is 100% conserved across the evolutionary tree, indicating its crucial function. CONCLUSION: Here we identify the first Taiwanese cerulean cataract family carrying a CRYBB2_Q155X mutation.

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.

Immune and Genetic Features of the Chromosome 22q11.2 Deletion (DiGeorge Syndrome).

PURPOSE OF REVIEW: This review provides an update on the progress in identifying the range of immunological dysfunction seen in DiGeorge syndrome and on more recent diagnostic and treatment approaches. RECENT FINDINGS: Clinically, the associated thymic hypoplasia/aplasia is well known and can have profound effects on T cell function. Further, the humoral arm of the immune system can be affected, with hypogammaglobulinemia and poor vaccine-specific antibody response. Additionally, genetic testing utilizing chromosomal microarray demonstrates a small but significant number of 22q11 deletions that are not detectable by standard FISH testing. The recent addition of a TREC assay to newborn screening can identify a subset of infants whose severe immune defects may result from 22q11 deletion. This initial presentation now also places the immunologist in the role of "first responder" with regard to diagnosis and management of these patients. DiGeorge syndrome reflects a clinical phenotype now recognized by its underlying genetic diagnosis, chromosome 22q11.2 deletion syndrome, which is associated with multisystem involvement and variable immune defects among patients. Updated genetic and molecular techniques now allow for earlier identification of immune defects and confirmatory diagnoses, in this disorder with life-long clinical issues.