Clinical Suspicion Of 22q11 Research Articles

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.

Loss of heterozygosity (LOH) Analysis in individuals with developmental delay/congenital anomalies previously investigated for 22q11.2 Deletion Syndrome

LLoss of heterozygosity (LOH) also called absence of heterozygosity (AOH) or regions of homozygosity (ROH) can be detected by SNP-array analysis. It is observed in regions identical by descent or occurs because of errors in the mechanisms of recombination between homologous chromosomes, DNA replications or DNA repair. The 22q11.2 deletion syndrome (22q11.2DS) has a prevalence of 1/4000 live births and an extensive clinical variability. About 30% of individuals with 22q11.2DS clinical suspicion have been diagnosed with the typical 22q11.2 deletion and other genomic imbalances are often reported related to similar phenotypes. However, most of patients remain without an etiological diagnosis. Currently, there are few studies about LOH in individuals with developmental delay/congenital anomalies. The aim of this study is to describe the preliminary results of LOH analysis in individuals with clinical suspicion of 22q11.2DS. Inclusion criteria was individuals with clinical suspicion without the typical 22q11.2 deletions, previously tested by Fluorescent in situ Hybridization (FISH) or Multiplex Ligation Probe-dependent Amplification (MLPA). Exclusion criteria was parental consanguinity. A total of 124 individuals were investigated by chromosomal microarray analysis (CMA) using the CytoScan HD or 750K Array (Affymetrix®). Data were compared with a database composed by 114 control individuals from Brazilian general population. We considered only LOH biggest than 3Mb and not frequent (<1%) in control individuals. The presence of LOH was more often in the patients than in the control group (12,1% against 3,5%). In the patient group the LOH size were between 3,3Mb and 46,2Mb (average size 22,7Mb) and in the control group it was between 3,1Mb and 8,5Mb (average size 6,0Mb). It was observed only one large LOH for almost all patients, and for almost all the control group it was observed two small LOHs. Among patients with LOH, six also carried VOUS (variants of uncertain significance) and one had a pathogenic imbalance. Laboratorial confirmations and genotype-phenotype correlation are in progress. Our results clearly show a higher proportion and bigger size of LOHs in individuals with developmental delay/congenital anomalies and a possible applicability of LOH analysis as a diagnostic approach in individuals with the same characteristics of the present sample.Support: Fapesp and CNPq

Genomic findings in patients with clinical suspicion of 22q11.2 deletion syndrome

Chromosome 22q11.2 deletion syndrome, one of the most common human genomic syndromes, has highly heterogeneous clinical presentation. Patients usually harbor a 1.5 to 3 Mb hemizygous deletion at chromosome 22q11.2, resulting in pathognomic TBX1, CRKL and/or MAPK1 haploinsufficiency. However, there are some individuals with clinical features resembling the syndrome who are eventually diagnosed with genomic disorders affecting other chromosomal regions. The objective of this study was to evaluate the additive value of high-resolution array-CGH testing in the cohort of 41 patients with clinical features of 22q11.2 deletion syndrome and negative results of standard cytogenetic diagnostic testing (karyotype and FISH for 22q11.2 locus). Array-CGH analysis revealed no aberrations at chromosomes 22 or 10 allegedly related to the syndrome. Five (12.2 %) patients were found to have other genomic imbalances, namely 17q21.31 microdeletion syndrome (MIM#610443), 1p36 deletion syndrome (MIM#607872), NF1 microduplication syndrome (MIM#613675), chromosome 6pter-p24 deletion syndrome (MIM#612582) and a novel interstitial deletion at 3q26.31 of 0.65 Mb encompassing a dosage-dependent gene NAALADL2. Our study demonstrates that the implementation of array-CGH into the panel of classic diagnostic procedures adds significantly to their efficacy. It allows for detection of constitutional genomic imbalances in 12 % of subjects with negative result of karyotype and FISH targeted for 22q11.2 region. Moreover, if used as first-tier genetic test, the method would provide immediate diagnosis in ∼40 % phenotypic 22q11.2 deletion subjects.

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

The 22q11.2 deletion is the most frequent interstitial deletion in humans and presents a wide phenotypic spectrum, with over 180 clinical manifestations described. Distinct studies have detected frequencies of the deletion ranging from 0 % to 75 %, depending on the studied population and selection criteria adopted. Due to the lack of consensus in this matter, several studies have been conducted aiming to define which patients would be eligible for screening; however, the issue is still up for debate. In order to contribute to the delineation of possible clinical and dysmorphologic guidelines to optimize decision making in the clinical setting, 194 individuals with variable features of the 22q11.2 deletion syndromes (22q11.2DS) were evaluated. Group I, clinical suspicion of 22q11.2DS with palatal anomalies; Group II, clinical suspicion without palatal anomalies; Group III, cardiac malformations associated with the 22q11.2DS; and Group IV, juvenile-onset schizophrenia. Multiplex ligation-dependent probe amplification was used for screening the 22q11.2 deletion, which was detected in 45 patients (23.2 %), distributed as such: Group I, 35/101 (34.7 %); Group II, 4/18 (22.2 %); Group III, 6/52 (11.5 %); and Group IV, 0/23 (0 %). Clinical data were analyzed by frequency distribution and statistically. Based on the present results and on the review of the literature, we propose a set of guidelines for screening patients with distinct manifestations of the 22q11.2DS in order to maximize resources. In addition, we report the dysmorphic features which we found to be statistically correlated with the presence of the 22q11.2DS.

A Case of Congenitally Absent Left Internal Carotid Artery: Vascular Malformations in 22q11.2 Deletion Syndrome

Our report is on a Hispanic boy for whom, shortly after birth, clinical suspicion of 22q11.2 deletion syndrome (22q11.2DS) was raised as a result of his characteristic features, including facial dysmorphisms and hypotonia. The 22q11.2DS was confirmed by fluorescence in situ hybridization (FISH), noting a 22q11.2 deletion. Further evaluation revealed complete congenital absence of the left internal carotid artery and focal pachygyria of the left hemisphere. Multiple cardiac and vascular anomalies have been previously described in 22q11 deletion syndrome, but congenital absence of the internal carotid has not been previously reported in the literature. We present a clinical case report in detail of this unique 22q11.2 deletion syndrome associated finding.

Síndrome de deleção 22q11.2: importância da avaliação clínica e técnica de FISH

The 22q11.2 deletion syndrome nowadays is considered one of the most often observed genetic diseases in humans. It is clinically characterized by a rather wide phenotypic spectrum, with more than 180 clinical features physical as well as behavioral, already described. However, none is pathognomonic or obligatory which makes diagnosis even more difficult. Thus, this study intended to determine the prevalence and clinical characteristics of patients with 22q11.2 microdeletion in a selected sample of subjects with clinical suspicion of 22q11.2 deletion syndrome and normal karyotype. A selected sample of 30 patients with clinical suspicion of 22q11.2 deletion syndrome and normal karyotype was evaluated by application of a standard clinical protocol and cytogenetic analysis with fluorescent in situ hybridization. 22q11.2 microdeletion was identified in 3 patients (10%), a prevalence similar to the majority of published studies, which ranged from 4 to 21%. The 22q11.2 deletion syndrome patients in this study were characterized by a variable phenotype and shared few clinical features, in agreement with the literature description. These findings strengthen the idea that clinical diagnosis of 22q11.2 deletion syndrome is difficult due to the large phenotypic variability. Therefore a detailed clinical evaluation associated to a sensitive test such as fluorescent in situ hybridization analysis is crucial for the identification of these patients.