Defining new guidelines for screening the 22q11.2 deletion based on a clinical and dysmorphologic evaluation of 194 individuals and review of the literature

Neuropsychological Profile of 25 Brazilian Patients with 22q11.2 Deletion Syndrome: Effects of Clinical and Socioeconomic Variables

The 22q11.2 deletion syndrome (22q11.2DS) is associated with a heterogeneous neurocognitive phenotype, which includes psychiatric disorders. However, few studies have investigated the influence of socioeconomic variables on intellectual variability. The aim of this study was to investigate the cognitive profile of 25 patients, aged 7 to 32 years, with a typical ≈3 Mb 22q11.2 deletion, considering intellectual, adaptive, and neuropsychological functioning. Univariate linear regression analysis explored the influence of socioeconomic variables on intellectual quotient (IQ) and global adaptive behavior. Associations with relevant clinical conditions such as seizures, recurrent infections, and heart diseases were also considered. Results showed IQ scores ranging from 42 to 104. Communication, executive functions, attention, and visuoconstructive skills were the most impaired in the sample. The study found effects of access to quality education, family socioeconomic status (SES), and caregiver education level on IQ. Conversely, age at diagnosis and language delay were associated with outcomes in adaptive behavior. This characterization may be useful for better understanding the influence of social-environmental factors on the development of patients with 22q11.2 deletion syndrome, as well as for intervention processes aimed at improving their quality of life.

Genome Sequencing in an Individual Presenting with 22q11.2 Deletion Syndrome and Juvenile Idiopathic Arthritis

Juvenile idiopathic arthritis is a heterogeneous group of diseases characterized by arthritis with poorly known causes, including monogenic disorders and multifactorial etiology. 22q11.2 proximal deletion syndrome is a multisystemic disease with over 180 manifestations already described. In this report, the authors describe a patient presenting with a short stature, neurodevelopmental delay, and dysmorphisms, who had an episode of polyarticular arthritis at the age of three years and eight months, resulting in severe joint limitations, and was later diagnosed with 22q11.2 deletion syndrome. Investigation through Whole Genome Sequencing revealed that he had no pathogenic or likely-pathogenic variants in both alleles of the MIF gene or in genes associated with monogenic arthritis (LACC1, LPIN2, MAFB, NFIL3, NOD2, PRG4, PRF1, STX11, TNFAIP3, TRHR, UNC13DI). However, the patient presented 41 risk polymorphisms for juvenile idiopathic arthritis. Thus, in the present case, arthritis seems coincidental to 22q11.2 deletion syndrome, probably caused by a multifactorial etiology. The association of the MIF gene in individuals previously described with juvenile idiopathic arthritis and 22q11.2 deletion seems unlikely since it is located in the distal and less-frequently deleted region of 22q11.2 deletion syndrome.

Variants in KMT2A in Three Individuals with Previous Suspicion of 22q11.2 Deletion Syndrome

The condition known as 22q11.2 deletion syndrome (MIM #188400) is a rare disease with a highly variable clinical presentation including more than 180 features; specific guidelines for screening individuals have been used to support clinical suspicion before confirmatory tests by Brazil's Craniofacial Project. Of the 2568 patients listed in the Brazilian Database on Craniofacial Anomalies, 43 individuals negative for the 22q11.2 deletion syndrome were further investigated through whole-exome sequencing. Three patients (6.7%) presented with heterozygous pathogenic variants in the KMT2A gene, including a novel variant (c.6158+1del) and two that had been previously reported (c.173dup and c.3241C>T); reverse phenotyping concluded that all three patients presented features of Wiedemann-Steiner syndrome, such as neurodevelopmental disorders and dysmorphic facial features (n = 3), hyperactivity and anxiety (n = 2), thick eyebrows and lower-limb hypertrichosis (n = 2), congenital heart disease (n = 1), short stature (n = 1), and velopharyngeal insufficiency (n = 2). Overlapping features between 22q11.2 deletion syndrome and Wiedemann-Steiner syndrome comprised neuropsychiatric disorders and dysmorphic characteristics involving the eyes and nose region; velopharyngeal insufficiency was seen in two patients and is an unreported finding in WDSTS. Therefore, we suggest that both conditions should be included in each other's differential diagnoses.

Chromosome 22q11.2 Deletion Syndrome: A Comprehensive Review of Molecular Genetics in the Context of Multidisciplinary Clinical Approach

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.

Coexisting Conditions Modifying Phenotypes of Patients with 22q11.2 Deletion Syndrome

22q11.2 deletion syndrome (22q11.2DS) is the most common genomic disorder with an extremely broad phenotypic spectrum. The aim of our study was to investigate how often the additional variants in the genome can affect clinical variation among patients with the recurrent deletion. To examine the presence of additional variants affecting the phenotype, we performed microarray in 82 prenatal and 77 postnatal cases and performed exome sequencing in 86 postnatal patients with 22q11.2DS. Within those 159 patients where array was performed, 5 pathogenic and 5 likely pathogenic CNVs were identified outside of the 22q11.2 region. This indicates that in 6.3% cases, additional CNVs most likely contribute to the clinical presentation. Additionally, exome sequencing in 86 patients revealed 3 pathogenic (3.49%) and 5 likely pathogenic (5.81%) SNVs and small CNV. These results show that the extension of diagnostics with genome-wide methods can reveal other clinically relevant changes in patients with 22q11 deletion syndrome.

The impact of 22q11.2 copy-number variants on human traits in the general population

While extensively studied in clinical cohorts, the phenotypic consequences of 22q11.2 copy-number variants (CNVs) in the general population remain understudied. To address this gap, we performed a phenome-wide association scan in 405,324 unrelated UK Biobank (UKBB) participants by using CNV calls from genotyping array. We mapped 236 Human Phenotype Ontology terms linked to any of the 90 genes encompassed by the region to 170 UKBB traits and assessed the association between these traits and the copy-number state of 504 genotyping array probes in the region. We found significant associations for eight continuous and nine binary traits associated under different models (duplication-only, deletion-only, U-shape, and mirror models). The causal effect of the expression level of 22q11.2 genes on associated traits was assessed through transcriptome-wide Mendelian randomization (TWMR), revealing that increased expression of ARVCF increased BMI. Similarly, increased DGCR6 expression causally reduced mean platelet volume, in line with the corresponding CNV effect. Furthermore, cross-trait multivariable Mendelian randomization (MVMR) suggested a predominant role of genuine (horizontal) pleiotropy in the CNV region. Our findings show that within the general population, 22q11.2 CNVs are associated with traits previously linked to genes in the region, and duplications and deletions act upon traits in different fashions. We also showed that gain or loss of distinct segments within 22q11.2 may impact a trait under different association models. Our results have provided new insights to help further the understanding of the complex 22q11.2 region.

An overview of the trajectory of Brazilian individuals with 22q11.2 deletion syndrome until diagnosis

Background

22q11.2 deletion syndrome (22q11.2DS) is a rare disease with an important characteristic—clinical heterogeneity. The diversity of organs, regions, and systems of the body that can be affected requires periodic updating of health professionals so that they can recognize these clinical signs as belonging to 22q11.2DS. Updated professionals are equally important for the appropriate and timely clinical management of individuals with a positive diagnosis. In this context, this article aimed to map and analyze the access to healthcare for individuals with 22q11.2DS until the moment of diagnosis.

Results

We analyzed the clinical data of 111 individuals with 22q11.2DS registered in the Brazilian Database on Craniofacial Anomalies (BDCA) from 2008 to 2020. In this study, individuals were diagnosed at a median age of 9 years (mean = 9.7 years). Before the genetic investigation, they accessed 68.75% of the internationally recommended evaluations available at BDCA. Recurrent 22q11.2DS clinical manifestations such as delayed neuropsychomotor development, lip and/or palate defects, cardiac malformation and/or hematological/immunological alteration co-occurred in at least 72.06% of individuals. Cardiac malformation was the only clinical alteration that lowered the median diagnostic age, corresponding to 6.5 years of age with a cardiac malformation versus 11 years of age without one (p = 0.0006).

Conclusions

In Brazil, 22q11.2 DS is under-recognized, and early diagnosis and management of affected individuals are still a distant reality. In this sense, 22q11.2 DS suspicion followed by the elimination of obstacles for its diagnosis confirmation is essential to increase life expectancy and improve the quality of life of these individuals in Brazil.

Care of Children with DiGeorge Before and After Cultured Thymus Tissue Implantation

Background

Children with complete DiGeorge anomaly (cDGA) have congenital athymia plus a myriad of other challenging clinical conditions. The term cDGA encompasses children with congenital athymia secondary to 22q11.2DS, CHARGE syndrome (coloboma, heart defects, choanal atresia, growth or mental retardation, genital abnormalities, and ear abnormalities and/or deafness), and other genetic abnormalities. Some children have no known genetic defects. Since 1993, more than 100 children with congenital athymia have been treated with cultured thymus tissue implantation (CTTI). Naïve T cells develop approximately 6 to 12 months after CTTI. Most of the children had significant comorbidities such as heart disease, hypoparathyroidism, and infections requiring complex clinical care post cultured thymus tissue implantation (CTTI).

Objective

The purpose of this guidance is to assist multidisciplinary teams in caring for children with cDGA both before and after CTTI.

Methods

Thirty-one specialists, in addition to the authors, were asked to share their experience in caring for children with cDGA at Duke University Health System, before and after CTTI. These specialists included physicians, nurses, dentists, therapists, and dieticians.

Results

The goal of a multidisciplinary approach is to have children in the best possible condition for receiving CTTI and provide optimal care post CTTI through development of naïve T cells and beyond. The CTT (cultured thymus tissue) must be protected from high doses of steroids which can damage CTT. Organs must be protected from adverse effects of immunosuppression.

Conclusion

Creating a multidisciplinary team and a detailed plan of care for children with cDGA is important for optimal outcomes.

Brazil's Craniofacial Project: Different approaches on orofacial clefts and 22q11.2 deletion syndrome

This article reports the present situation of Brazilian health care in genetics for Orofacial Cleft (OFC) and 22q11.2 Deletions Syndrome (22q11.2 DS) based on research conducted by Brazil's Craniofacial Project (BCFP). Established in 2003, BCFP is a voluntary and cooperative network aiming to investigate the health care of people with these diseases and other craniofacial anomalies. The initiatives and research results are presented in four sections: (a) a comprehensive report of the Brazilian public health system in craniofacial genetics; (b) multicentric studies developed on OFC and 22q11.2 DS; (c) education strategies focused on addressing these conditions for both population and health-care professionals; and (d) the nosology through the Brazilian Database on Craniofacial Anomalies (BDCA). Since 2006, BDCA uses a standardized method with detailed clinical data collection, which allows for conducting studies on nosology, genotype-phenotype correlations, and natural history; data can also contribute to public policies. Currently, the BDCA stores data on 1,724 individuals, including 1,351 (78.36%) who were primarily admitted due to OFC and 373 (21.63%) with clinical suspicion of 22q11.2 DS. Chromosomal abnormalities/genomic imbalances were represented by 92/213 (43.19%) individuals with syndromic OFC, including 43 with 22q11.2 DS, which indicates the need for chromosomal microarray analysis in this group. The nosologic diversity reinforces that monitoring clinical is the best strategy for etiological investigation. BCFP's methodology has introduced the possibility of increasing scientific knowledge and genetic diagnosis of OFC and 22q11.2 DS to in turn improve health care and policies for this group of diseases.

Clinical Features to Predict 22q11.2 Deletion Syndrome Proven by Molecular Genetic Testing

The 22q11.2 deletion syndrome (22q11.2 DS) is the most common microdeletion syndrome with a wide variety of clinical features. However, as there are no clinical criteria for diagnosis, confirmation is solely done by genetic tests if clinicians recognize the syndrome. Therefore, we aimed to identify clinical features that may help clinicians recognize 22q11.2 DS. Participants with at least two anomalies were enrolled, complete patient history and physical examinations were performed, then multiplex ligation-dependent probe amplification (MLPA) analysis for 22q11.2 DS was utilized. We identified 11/48 (23%) cases with 22q11.2 DS. Palatal anomalies, hypocalcemia, and ≥3 affected body systems were highly significant presentations in the 22q11.2 DS group versus the group without deletion ( p  < 0.05). Therefore, a comprehensive physical examination is crucial at identifying any subtle features which may lead to testing and a definite diagnosis.

Childhood-Onset Schizophrenia and Early-onset Schizophrenia Spectrum Disorders: An Update

The clinical severity, impact on development, and poor prognosis of childhood-onset schizophrenia may represent a more homogeneous group. Positive symptoms in children are necessary for the diagnosis, and hallucinations are more often multimodal. In healthy children and children with a variety of other psychiatric illnesses, hallucinations are not uncommon and diagnosis should not be based on these alone. Childhood-onset schizophrenia is an extraordinarily rare illness that is poorly understood but seems continuous with the adult-onset disorder. Once a diagnosis is confirmed, aggressive medication treatment combined with family education and individual counseling may prevent further deterioration.

Association between phenotype and deletion size in 22q11.2 microdeletion syndrome: systematic review and meta-analysis

BACKGROUND

Chromosome 22q11.2 microdeletion syndrome, a disorder caused by heterozygous loss of genetic material in chromosome region 22q11.2, has a broad range of clinical symptoms. The most common congenital anomalies involve the palate in 80% of patients, and the heart in 50-60% of them. The cause of the phenotypic variability is unknown. Patients usually harbor one of three common deletions sizes: 3, 2 and 1.5 Mb, between low copy repeats (LCR) designated A-D, A-C and A-B, respectively. This study aimed to analyze the association between these 3 deletion sizes and the presence of congenital cardiac and/or palatal malformations in individuals with this condition. A systematic review and meta-analysis were conducted, merging relevant published studies with data from Chilean patients to increase statistical power.

RESULTS

Eight articles out of 432 were included; the data from these studies was merged with our own, achieving a total of 1514 and 487 patients to evaluate cardiac and palate malformations, respectively. None of the compared deleted chromosomal segments were statistically associated with cardiac defects (ORAB v/s AC-AD: 0.654 [0.408-1.046]; OR AD v/s AB-AC: 1.291 [0.860-1.939]) or palate anomalies (ORAB v/s AC-AD: 1.731 [0.708-4.234]; OR AD v/s AB-AC: 0.628 [0.286-1.382]).

CONCLUSIONS

The lack of association between deletion size and CHD or PA found in this meta-analysis suggests that deletion size does not explain the incomplete penetrance of these 2 major manifestations, and that the critical region for the development of heart and palatal abnormalities is within LCR A-B, the smallest region of overlap among the three deletion sizes.

Testing criteria for 22q11.2 deletion syndrome: preliminary results of a low cost strategy for public health

BACKGROUND

The clinical heterogeneity of the 22q11.2 Deletion Syndrome (22q11.2DS - OMIM, #188400 and #192430) is a universal challenge leading to diagnostic delay. The aim of this study was to evaluate a low cost strategy for the diagnosis of this condition based upon clinical criteria previously reported. Health professionals, who collected clinical data, from twelve centers were trained in those criteria, which were summed through an online application (CranFlow).

RESULTS

Clinical and laboratorial data of 347 individuals registered from 2008 to 2017 in the Brazilian Database on Craniofacial Anomalies/22q11.2 Deletion Syndrome, were reviewed. They were divided in two groups: (I) 168 individuals investigated before the definition of the criteria and (II) 179 individuals investigated after the criteria application. All of them were investigated for 22q11.2DS by Fluorescent in situ Hybridization (FISH) and/or Multiplex Ligation Probe-dependent Amplification (MLPA), detecting 98 cases with 22q11.2DS. Among the individuals with 22q11.2DS in Group II, 42/53 (79.25%) fulfilled the proposed criteria against 11/53 (20.75%) who did not fulfill them (p < .0001). The association of congenital heart diseases with high predictive value for 22q11.2DS and hypernasal voice were significantly associated to the presence of 22q11.2DS (p = 0.0172 and p < .0001, respectively). In addition, 22q11.2DS was confirmed 3.82 more times when the individuals fulfilled the proposed criteria. Of the 249 cases negative for the typical deletion in 22q11.2, Chromosomal Microarray Analysis (CMA) was performed in 132 individuals and detected pathogenic alterations at other genomic regions in 19 individuals, and variants of uncertain clinical significance in 31 cases.

CONCLUSIONS

Therefore, a locus-specific approach could be used to individuals with positive criteria as a cost-effective alternative for 22q11.2DS diagnosis. The authors discuss advantages and suggest ways of implementing this approach to investigate 22q11.2DS in a public health system.

Analysis of gene copy number variations in patients with congenital heart disease using multiplex ligation-dependent probe amplification

OBJECTIVE

At the molecular and cellular levels, heart development entails the precise orchestration of genetic events such as the interplay of master transcriptional regulators, signaling pathways, and chromatin remodeling. Recent studies among patients with congenital heart disease (CHD) have shown the importance of recurrent copy number variations (CNVs) in a significant number of patients. Recurrent CNVs that span several genes may affect other important organs, besides the heart. Because CHD may be the first presenting symptom in such patients, the analysis of recurrent CNVs in the genomic regions containing genes associated with CHD in patients referring to cardiology clinics may lead to an early diagnosis and the treatment of extracardiac symptoms in these patients. In this study, we aimed to screen CNVs of genomic regions including GATA4, NKX2-5, TBX5, BMP4, and CRELD1 genes and to analyse the 22q11.2 chromosomal region in apparently nonsyndromic patients with cardiac septal defects.

METHODS

Genomic regions including GATA4, NKX2-5, TBX5, BMP4, and CRELD1 genes and the 22q11.2 chromosomal region were analyzed in apparently nonsyndromic 45 patients with cardiac septal defects using the MLPA P-311 A2 Congenital Heart Disease kit. Multiplex ligationdependent probe amplification (MLPA) is an established technique for the detection of known CNVs. MLPA is substantially less expensive than array CGH and is relatively simple to use for clinicians without specific expertise in genomic technology; thus, MLPA could be used as a first-tier screening assay.

RESULTS

We screened 45 patients with cardiac septal defects for CNVs using the MLPA P-311 A2 kit. We identified three CNVs (n=3/45, 6.66%) and three 22q11 deletions. The CNVs were confirmed using fluorescence in situ hybridization.

CONCLUSION

Our study confirmed that the analysis of recurrent CNVs using the MLPA assay within pediatric cardiology clinics can led to an early syndrome diagnosis in nonsyndromic patients with CHD.

Evaluation of loss of heterozygosity of chromosome 22q11.21 region in patients with congenital heart diseases

The 22q11.21 region is prone to low-copy repeats events that lead to congenital anomaly disorders. We tested genomic DNA of 20 families with non-syndromic CHD patients using a set of three known consecutive high polymorphic short tandem repeat (STR) markers along the 22q11.21 region; D22S941, D22S944 and D22S264 loci. We found loss of heterozygosity (LOH) in D22S941 locus in 2 out of 20 families (10%) with 2 offspring affected by ASD combined with PS and TOF respectively. No LOH found in D22S944 and D22S264 loci either in affected cases or control group and no LOH found in D22S941 in the control group. Also we observed that D22S944 locus prone to be less allele diversity than D22S941 and D22S264 loci.

Schizophrenia in DiGeorge Syndrome: A Unique Case Report

Herein we present the unique case of a 21-year-old African American woman who presented with psychotic features and the incidental finding of basal ganglia calcifications on computed tomography (CT) scan of the head. She was initially presumed to have Fahr's syndrome in the context of idiopathic bilateral basal ganglia calcifications and psychotic features. Genetic testing performed revealed the deletion of 22q11.2, thus establishing the diagnosis of DiGeorge syndrome. This case highlights the importance of noticing subtle physical exam findings along with laboratory findings as this led to the diagnosis of DiGeorge syndrome for this patient. This case is unique in two aspects; first, the finding of basal ganglia calcification via CT of the brain in patients with DiGeorge syndrome has rarely been reported in the literature. Second, this case highlights the strong genetic predisposition for schizophrenia in patients with DiGeorge syndrome.

22q11.2 Deletion Syndrome in Colombian Patients With Syndromic Cleft Lip and/or Palate

The objective of this work was to identify 22q11.2 chromosomal deletion in patients with cleft lip and/or cleft palate and suggestive syndromic phenotype in Colombian patients. We studied 49 patients with cleft lip and/or cleft palate, exhibiting additional clinical findings linked to 22q11.2 deletion syndrome. All patients underwent high-resolution G-banded karyotyping, multiplex ligation-dependent probe amplification, and clinical evaluation by a geneticist. Seven patients presented 22q11.2 deletion and 2 patients had other chromosomal abnormalities. In conclusion, this study contributes with new data for genetic etiology in syndromic conditions of oral fissures.

Diagnostic Approach to Microdeletion Syndromes Based on 22q11.2 Investigation: Challenges in Four Cases

In the last few decades, different methods for the detection of genomic imbalances, such as the microdeletion syndromes, were developed. The 22q11.2 deletion syndrome (22q11.2DS) is the most common microdeletion syndrome and presents wide clinical heterogeneity. The aim of this study was to describe 4 unusual cases of genomic imbalances found in individuals with suspected microdeletion syndromes. Different methods were necessary to complete the diagnosis and to obtain information for genetic counseling. The study was retrospective and descriptive. From August 2014 to December 2015, 39 individuals were assessed using FISH and/or MLPA; in 15 cases, chromosomal microarray (CMA) analysis was carried out. Of 39 registered individuals, we found deletions in the 22q11.2 region in 10 individuals (8 individuals with 22q11.2DS and 2 individuals presenting with atypical deletions in the 22q11.2 region: 1 distal deletion and 1 central deletion). In one case with a typical 22q11.2 deletion, a familial balanced translocation was detected. In another case without a 22q11.2 deletion, a 6p duplication concomitant with a 9p deletion was detected by CMA. Clinical data are reported and diagnostic investigations are discussed. Essential aspects for the understanding of different diagnostic techniques of genomic imbalances are considered, and the 4 cases described underline the complexity and the difficulties involved in the diagnostic process. The approach is informative for clinical practice and may be applied in other contexts of genomic imbalance investigation in microdeletion syndromes.

Hypothyroidism associated with parathyroid disorders

Hypothyroidism may occur in association with congenital parathyroid disorders determining parathyroid hormone insufficiency, which is characterized by hypocalcemia and concomitant inappropriately low secretion of parathormone (PTH). The association is often due to loss of function of genes common to thyroid and parathyroid glands embryonic development. Hypothyroidism associated with hypoparathyroidism is generally mild and not associated with goiter; moreover, it is usually part of a multisystemic involvement not restricted to endocrine function as occurs in patients with 22q11 microdeletion/DiGeorge syndrome, the most frequent disorders. Hypothyroidism and hypoparathyroidism may also follow endocrine glands' damages due to autoimmunity or chronic iron overload in thalassemic disorders, both genetically determined conditions. Finally, besides PTH deficiency, hypocalcemia can be due to PTH resistance in pseudohypoparathyroidism; when hormone resistance is generalized, patients can suffer from hypothyroidism due to TSH resistance. In evaluating patients with hypothyroidism and hypocalcemia, physical examination and clinical history are essential to drive the diagnostic process, while routine genetic screening is not recommended.

[Diagnosis of 22q11.2 deletion syndrome in the context of newly developed psychosis]

22q11.2 deletion syndrome (clinically also known as velocardiofacial or DiGeorge syndrome) is the most common human microdeletion syndrome and can be associated with a multitude of clinical features. In this article we report the case of a 22-year-old patient from Austria who was diagnosed with previously unknown 22q11.2 deletion syndrome in the context of newly developed psychosis. Using this case as an example, we then discuss the implications of 22q11.2 deletion syndrome for clinical psychiatric practice.

22q11.2 Deletion Syndrome: Laboratory Diagnosis and TBX1 and FGF8 Mutation Screening

Velocardiofacial syndrome is one of the recognized forms of chromosome 22q11.2 deletion syndrome (22q11.2 DS) and has an incidence of 1 of 4,000 to 1 of 6,000 births. Nevertheless, the 22q11 deletion is not found in several patients with a 22q11.2 DS phenotype. In this situation, other chromosomal aberrations and/or mutations in the T-box 1 transcription factor C (TBX1) gene have been detected in some patients. A similar phenotype to that of the 22q11.2 DS has been reported in animal models with mutations in fibroblast growth factor 8 (Fgf8) gene. To date, FGF8 mutations have not been investigated in humans. We tested a strategy to perform laboratory testing to reduce costs in the investigation of patients presenting with the 22q11.2 DS phenotype. A total of 109 individuals with clinical suspicion were investigated using GTG-banding karyotype, fluorescence in situ hybridization, and/or multiplex ligation-dependent probe amplification. A conclusive diagnosis was achieved in 33 of 109 (30.2%) cases. In addition, mutations in the coding regions of TBX1 and FGF8 genes were investigated in selected cases where 22q11.2 deletion had been excluded, and no pathogenic mutations were detected in both genes. This study presents a strategy for molecular genetic characterization of patients presenting with the 22q11.2 DS using different laboratory techniques. This strategy could be useful in different countries, according to local resources. Also, to our knowledge, this is the first investigation of FGF8 gene in humans with this clinical suspicion.

Delineation of a recognizable phenotype for the recurrent LCR22-C to D/E atypical 22q11.2 deletion

The 22q11.2 deletion syndrome is typically caused by haploinsufficiency of a 3 Mb region that extends from LCR22-A until LCR22-D, while the recurrent recombination between any of the LCR22-D to H causes the 22q11.2 distal deletion syndrome. Here, we describe three patients with a de novo atypical ∼1.4 Mb 22q11.2 deletion that involves LCR22-C to a region beyond D (LCR22-C to D/E), encompassing the distal portion of the typical deleted region and the proximal portion of the distal deletion. We also review six previous published patients with the same rearrangement and compare their features with those found in patients with overlapping deletions. Patients with LCR22-C to D/E deletion present a recognizable phenotype characterized by facial dysmorphic features, high frequency of cardiac defects, including conotruncal defects, prematurity, growth restriction, microcephaly, and mild developmental delay. Genotype-phenotype analysis of the patients indicates that CRKL and MAPK1 genes play an important role as causative factors for the main clinical features of the syndrome. In particular, CRKL gene seems to be involved in the occurrence of conotruncal cardiac anomalies, mainly tetralogy of Fallot. © 2016 Wiley Periodicals, Inc.

Mechanisms of germ line genome instability

During meiosis, numerous DNA double-strand breaks (DSBs) are formed as part of the normal developmental program. This seemingly destructive behavior is necessary for successful meiosis, since repair of the DSBs through homologous recombination (HR) helps to produce physical links between the homologous chromosomes essential for correct chromosome segregation later in meiosis. However, DSB formation at such a massive scale also introduces opportunities to generate gross chromosomal rearrangements. In this review, we explore ways in which meiotic DSBs can result in such genomic alterations.

Early-onset Parkinson's Disease Associated with Chromosome 22q11.2 Deletion Syndrome

We herein report the case of a 43-year-old man with a 4-year history of resting tremor and akinesia. His resting tremor and rigidity were more prominent on the left side. He also presented retropulsion. His symptoms responded to the administration of levodopa. The patient also had a cleft lip and palate, cavum vergae, and hypoparathyroidism. A chromosome analysis disclosed a hemizygous deletion in 22q11.2, and he was diagnosed with early-onset Parkinson's disease associated with 22q11.2 deletion syndrome. However, the patient lacked autonomic nerve dysfunction, and his cardiac uptake of (123)I-metaiodobenzylguanidine was normal, indicating an underlying pathological mechanism that differed to that of sporadic Parkinson's disease.

Velocardiofacial syndrome in Mexican patients: Unusually high prevalence of congenital heart disease

INTRODUCTION

Velocardiofacial syndrome (VCFS) is the most common microdeletion syndrome with an incidence of 1:4000 live births. Its phenotype is highly variable with facial, velopharyngeal, cardiac, endocrine, immunologic and psychiatric abnormalities. It is caused by a microdeletion in chromosome 22q11.2.

OBJECTIVES

We present 7 years of experience evaluating patients with VCFS regarding their main clinical characteristics.

MATERIAL AND METHODS

The patients included were multidisciplinary evaluated and had a positive FISH analysis for del22q11.2.

RESULTS

A total of 62 patients were assessed, a 34 female/28 male ratio was observed with ages ranging from 9 days to 16 years, all but one patient had typical facial features. A diagnosis of congenital heart disease was established in 97% of the patients; other clinical characteristics were identified with different percentages such as cleft palate, and hypocalcaemia. Three cases had a familial presentation.

DISCUSSION

While the clinical findings of this study were in general terms in keeping with the literature, it is interesting the unexpectedly high percentage of congenital heart disease identified in Mexican children with VCFS that also was the main cause for clinical referral.

A French multicenter study of over 700 patients with 22q11 deletions diagnosed using FISH or aCGH

Although 22q11.2 deletion syndrome (22q11.2DS) is the most recurrent human microdeletion syndrome associated with a highly variable phenotype, little is known about the condition's true incidence and the phenotype at diagnosis. We performed a multicenter, retrospective analysis of postnatally diagnosed patients recruited by members of the Association des Cytogénéticiens de Langue Française (the French-Speaking Cytogeneticists Association). Clinical and cytogenetic data on 749 cases diagnosed between 1995 and 2013 were collected by 31 French cytogenetics laboratories. The most frequent reasons for referral of postnatally diagnosed cases were a congenital heart defect (CHD, 48.6%), facial dysmorphism (49.7%) and developmental delay (40.7%). Since 2007 (the year in which array comparative genomic hybridization (aCGH) was introduced for the routine screening of patients with intellectual disability), almost all cases have been diagnosed using FISH (96.1%). Only 15 cases (all with an atypical phenotype) were diagnosed with aCGH; the deletion size ranged from 745 to 2904 kb. The deletion was inherited in 15.0% of cases and was of maternal origin in 85.5% of the latter. This is the largest yet documented cohort of patients with 22q11.2DS (the most commonly diagnosed microdeletion) from the same population. French cytogenetics laboratories diagnosed at least 108 affected patients (including fetuses) per year from among a national population of ∼66 million. As observed for prenatal diagnoses, CHDs were the most frequently detected malformation in postnatal diagnoses. The most common CHD in postnatal diagnoses was an isolated septal defect.

8p23.1 Interstitial Deletion in a Patient with Congenital Cardiopathy, Neurobehavioral Disorders, and Minor Signs Suggesting 22q11.2 Deletion Syndrome

Copy number variation studies of known disorders have the potential to improve the characterization of clinical phenotypes and may help identifying candidate genes and their pathways. The authors described a child with congenital heart disease, microcephaly, facial dysmorphisms, developmental delay, learning difficulties, and behavioral problems. There was initially a clinical suspicion of 22q11.2 deletion syndrome (22q11.2 DS), but molecular cytogenetic analysis (array genomic hybridization [aGH]) showed the presence of a de novo 3.6-Mb interstitial microdeletion in 8p23.1. The main features of 8p23.1 DS include congenital heart disease and behavioral problems, in addition to minor dysmorphisms and mental delay. Therefore, this article highlights the application of aGH to investigate 8p23.1 deletion in nonconfirmed 22q11.2 DS patients presenting neurobehavioral disorders, congenital cardiopathy, and minor dysmorphisms.

[Absent or hypoplastic thymus: A marker for 22q11.2 microdeletion syndrome in case of polyhydramnios]

OBJECTIVES

In prenatal diagnosis of 22q11.2 microdeletion syndrome, without cardiac malformation or multiple associated congenital anomalies, we study the presence of polyhydramnios and its association with thymic dysgenesis.

MATERIALS AND METHODS

This was a multicenter retrospective observational study. It was performed in two multidisciplinary centers for prenatal diagnosis in the south of France between January 1, 2010 and June 30, 2013. Inclusion criteria were prenatal diagnosis of 22q11.2 deletion syndrome. We excluded from the study any fetus with cardiac malformation or multiple associated congenital anomalies.

RESULTS

During the inclusion period, eleven antenatal diagnoses of 22q11.2 microdeletion syndrome have been made. Six cases were excluded: 5 fetuses with cardiac malformation and one with multiple associated congenital anomalies. Therefore, five cases of isolated polyhydramnios were included. All 5 fetuses had a thymic dysgenesis: 3 had a thymic agenesis and 1 thymic hypoplasia diagnosed by sonography and 1 had a thymic agenesis diagnosed by retrospective reading of fetal MRI.

CONCLUSION

When faced with a polyhydramnios, the presence of a thymic dysgenesis should be search for by ultrasound screening and would alert to the possibility of a 22q11.2 microdeletion syndrome. The confirmation of this is diagnosis by amniocentesis would enable improved antenatal support for parents and would enable early implementation of the multidisciplinary neonatal care that is required to avoid serious complications of this syndrome.

22q11 deletion syndrome: current perspective

Chromosome 22q11 is characterized by the presence of chromosome-specific low-copy repeats or segmental duplications. This region of the chromosome is very unstable and susceptible to mutations. The misalignment of low-copy repeats during nonallelic homologous recombination leads to the deletion of the 22q11.2 region, which results in 22q11 deletion syndrome (22q11DS). The 22q11.2 deletion is associated with a wide variety of phenotypes. The term 22q11DS is an umbrella term that is used to encompass all 22q11.2 deletion-associated phenotypes. The haploinsufficiency of genes located at 22q11.2 affects the early morphogenesis of the pharyngeal arches, heart, skeleton, and brain. TBX1 is the most important gene for 22q11DS. This syndrome can ultimately affect many organs or systems; therefore, it has a very wide phenotypic spectrum. An increasing amount of information is available related to the pathogenesis, clinical phenotypes, and management of this syndrome in recent years. This review summarizes the current clinical and genetic status related to 22q11DS.

The many etiologies of neonatal hypocalcemic seizures

Seizures during the neonatal period have a broad differential diagnosis. Unlike in developing countries where hypovitaminosis D and hypocalcemia constitutes a major cause of infantile seizures, the number of neonatal seizures attributed to hypocalcemia in developed countries has decreased dramatically due to the improvement of infant formulas and vitamin D supplementation. In these countries, most infants that present with hypocalcemic seizures have underlying endocrinological etiologies rather than dietary insufficiencies. Here, we describe 3 cases of neonatal seizures due to hypocalcemia. Although the symptoms and calcium concentrations at presentation were similar in all 3 cases, the course of the disease and the final diagnosis for each were distinct. The cases are presented along with a brief review of the pathophysiology, differential diagnosis, and treatment of neonatal hypocalcemia.

Clinical and molecular cytogenetic studies of an unrecognised 22q11.2 deletion in three families

The phenotypic variability associated with 22q11.2 deletion syndrome (22q11.2DS) is well known. In the present study, the cases of three unrelated adult patients with chromosome 22q11.2DS and nearly normal features are described, along with their reproductive histories. Chromosomal analysis with fluorescent in situ hybridisation and genomic DNA analysis by microarrays were performed, as well as a clinical examination. The three patients were found to possess an identical breakpoint deletion at 22q11.2 by high-density whole-genome single nucleotide polymorphism microarray analysis. The patients had histories of two foetuses/infants with congenital heart defects. The underlying aetiology for the discordance in the phenotype in these patients is discussed. These observations provide additional data useful for patient counselling and guidelines for 22q11.2 clinical screening.

Reproductive Health Issues for Adults with a Common Genomic Disorder: 22q11.2 Deletion Syndrome

22q11.2 deletion syndrome (22q11.2DS) is the most common microdeletion syndrome in humans. Survival to reproductive age and beyond is now the norm. Several manifestations of this syndrome, such as congenital cardiac disease and neuropsychiatric disorders, may increase risk for adverse pregnancy outcomes in the general population. However, there are limited data on reproductive health in 22q11.2DS. We performed a retrospective chart review for 158 adults with 22q11.2DS (75 male, 83 female; mean age 34.3 years) and extracted key variables relevant to pregnancy and reproductive health. We present four illustrative cases as brief vignettes. There were 25 adults (21 > age 35 years; 21 female) with a history of one or more pregnancies. Outcomes for women with 22q11.2DS, compared with expectations for the general population, showed a significantly elevated prevalence of small for gestational age liveborn offspring (p < 0.001), associated mainly with infants with 22q11.2DS. Stillbirths also showed elevated prevalence (p < 0.05). Not all observed adverse events appeared to be attributable to transmission of the 22q11.2 deletion. Recurring issues relevant to reproductive health in 22q11.2DS included the potential impact of maternal morbidities, inadequate social support, unsafe sexual practices, and delayed diagnosis of 22q11.2DS and/or lack of genetic counseling. These preliminary results emphasize the importance of early diagnosis and long term follow-up that could help facilitate genetic counseling for men and women with 22q11.2DS. We propose initial recommendations for pre-conception management, educational strategies, prenatal planning, and preparation for possible high-risk pregnancy and/or delivery.

Classification, epidemiology, and genetics of orofacial clefts

Orofacial clefts (OFCs) include a broad range of facial conditions that differ in cause and disease burden. In the published literature, there is substantial ambiguity in both terminology and classification of OFCs. This article discusses the terminology and classification of OFCs and the epidemiology of OFCs. Demographic, environmental, and genetic risk factors for OFCs are described, including suggestions for family counseling. This article enables clinicians to counsel families regarding the occurrence and recurrence of OFCs. Although much of the information is detailed, it is intended to be accessible to all health professionals for use in their clinical practices.

Clinical Features in Patients With 22q11.2 Deletion Syndrome Ascertained by Palatal Abnormalities

OBJECTIVES

The aim of this study was to describe clinical features in subjects with palatal abnormalities and to assess the distribution of these features among those with and without 22q11.2 deletion.

DESIGN

Descriptive cohort.

PATIENTS

One hundred patients with palatal abnormalities and suspicion of 22q11.2 DS were included.

METHODS

All patients were evaluated by a clinical geneticist, who completed a standardized clinical protocol. The 22q11.2 deletion screening was performed with fluorescence in situ hybridization using the TUPLE1 probe and multiplex ligation-dependent probe amplification using the P250-A1 kit.

RESULTS

The 22q11.2 deletion was detected in 35 patients, in whom the most frequent clinical features were congenital heart disease (15/30 - 50%), developmental delay (19/35 - 54%), speech delay (20/35 - 57%), learning disabilities (27/35 - 77%), immunologic alterations (18/29 - 62%). In addition, the most common facial dysmorphisms in this group were long face (27/35 - 77%), typical nose (24/35 - 69%), and hooded eyelids (19/35 - 54%). Comparing features in patients with or without the deletion revealed significant differences (positively correlated with the deletion) for speech delay, learning disabilities, conductive hearing loss, number of dysmorphisms, long face, and hooded eyelids. Cleft lip and palate was negatively correlated with the deletion.

CONCLUSIONS

The presence of speech delay, learning disabilities, conductive hearing loss, long face, and hooded eyelids should reinforce the suspicion of 22q11.2 DS in patients with palatal abnormalities and would help professionals direct clinical follow-up of these patients.