Síndrome da deleção do braço curto do cromossomo 18: avaliação clínica e citogenômica

Chromosome 18p deletion syndrome [del(18p)] (OMIM 146390) has been well described in the literature with over 300 patients reported on, but few of them evaluated by cytogenomic techniques. Objective: We studied 12 patients with 18p deletion based on clinical, developmental and cytogenomic findings. Methods: The patients were evaluated by a specific clinical protocol, including immunological, endocrinological and neuropsychological assessments. The cytogenetic study was performed by G-banding karyotype, SNP-array (Genome-Wide Human SNP Array 6.0, Affymetrix) and FISH-BAC techniques. Results: A total of 12 patients, seven males and five females, previously diagnosed with 18p deletion were evaluated. The patients were classified in three groups according to the cytogenomic findings, as follows: five with pure 18p deletion (group I), two with ring chromosome 18 (group II) and five with 18p deletion associated with duplication or deletion of another chromosome (group III). Conclusions: The results showed a wide variation in intra- and inter-chromosomal rearrangements in patients, both inherited as de novo, as well as a wide variability of phenotypic manifestations and comorbidities. Although the literature indicates 18p11.1 as the most frequent breakpoint, our patients presented different breakpoints: 18p11.21 (5/12), 18p11.23 (2/12), 18p11.31 (4/12), and 18p11.32 (1/12). The main clinical findings were: proportionate short stature; microcephaly; ectopic pituitary; growth hormone deficiency; hypothyroidism; intellectual disability; cardiac anomalies; scoliosis; and keratosis pilaris. The distinguished facial dysmorphic features were: ocular hypertelorism; ptosis; and strabismus.The neuropsychological assessments showed IQ scores from borderline intellectual functioning to moderate intellectual disability. The SNP-array technique permitted a better chromosome breakpoint definition and, associated to the specific clinical protocol, provided a better genotype-phenotype correlation revealing genes that might influence the patient?s phenotype. Some genes located in the 18p deleted segment seem to play important roles in the patient?s phenotype, such as TGIF1, GNAL, LAMA1 and LPIN2 genes. The clinical protocol associated with cytogenomic results provided the recognition of relevant genes to the clinical manifestations found, such as holoprosencephaly microforms, keratosis pilaris, cryptorchidism, scoliosis and IgA deficiency. In addition, the multidisciplinary approach of this study allowed making recommendations for medical and neuropsychological evaluation on 18p deletion patients for better clinical monitoring and appropriate genetic counseling for each family.Avaliar uma amostra de pacientes com deleção 18p, sob os aspectos clínicos e citogenômicos a fim de aprimorar a correlação genótipo-fenótipo. Métodos: Os pacientes foram avaliados por meio de protocolo clínico específico, desenvolvido a partir da revisão da literatura, e de avaliações imunológica e neuropsicológica. Uma planilha de dados foi criada no programa Microsoft Excel com os achados clínicos, exames complementares, citogenômicos e avaliações neuropsicológica e imunológica para facilitar a realização da correlação genótipo-fenótipo. O estudo citogenômico foi realizado por cariotipagem sob bandamento G, técnicas de array genômico e de FISH (do inglês, Fluorescent In Situ Hybridization). Resultados e Conclusões: Foram estudados 12 pacientes diagnosticados previamente com deleção 18p, sendo sete do sexo masculino e cinco do sexo feminino. Os pacientes foram classificados em três grupos em função dos achados citogenômicos encontrados, sendo: cinco com deleção 18p pura (grupo I), dois com cromossomo 18 em anel (grupo II) e cinco com deleção 18p associada à duplicação ou deleção de outro cromossomo (grupo III). Os resultados revelaram grande variação de rearranjos intra e inter-cromossômicos nos pacientes, tanto herdados quanto de novo, assim como grande variabilidade de manifestações fenotípicas e comorbidades associadas. O estudo por array genômico permitiu a determinação mais acurada dos pontos de quebra e uma melhor correlação genótipo-fenótipo. A análise por FISH foi importante para a investigação da presença de translocação equilibrada nos pais dos pacientes. O protocolo clínico associado ao estudo citogenômico dos pacientes proporcionou o reconhecimento de genes relevantes para as manifestações clínicas encontradas tais como o espectro da holoprosencefalia, baixa estatura, queratose pilar, criptorquidia, escoliose e deficiência de IgA. Além disso, esta abordagem multidisciplinar permitiu a criação e proposição de recomendações para a avaliação médica e neuropsicológica de pacientes com deleção 18p, de forma a proporcionar um melhor seguimento clínico e aconselhamento genético adequado para cada família.Dados abertos - Sucupira - Teses e dissertações (2013 a 2016

Terminal 18q deletions are stabilized by neotelomeres

Background: All human chromosomes are capped by tandem repeat (TTAGGG)n sequences that protect them against end-to-end fusion and are essential to chromosomal replication and integrity. Therefore, after a chromosomal breakage, the deleted chromosomes must be stabilized by retaining the telomere or acquiring a new cap, by telomere healing or telomere capture. There are few reports with molecular approaches on the mechanisms involved in stabilization of 18q terminal deletions.Results: in this study we analyzed nine patients with 18q terminal deletion identified by G-banding and genomic array. FISH using PNA probe revealed telomeric signals in all deleted chromosomes tested. We fine-mapped breakpoints with customized arrays and sequenced six terminal deletion junctions. in all six deleted chromosomes sequenced, telomeric sequences were found directly attached to the breakpoints. Little or no microhomology was found at the breakpoints and none of the breaks sequenced were located in low copy repeat (LCR) regions, though repetitive elements were found around the breakpoints in five patients. One patient presented a more complex rearrangement with two deleted segments and an addition of 17 base pairs (bp).Conclusions: We found that all six deleted chromosomes sequenced were probably stabilized by the healing mechanism leading to a neotelomere formation.Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Universidade Federal de São Paulo, Dept Morphol & Genet, BR-04023900 São Paulo, BrazilEmory Univ, Sch Med, Dept Human Genet, Atlanta, GA 30322 USAUniversidade Federal de São Paulo, Dept Biophys, BR-04023900 São Paulo, BrazilUniversidade Federal de São Paulo, Dept Pathol, Lab Citogenom, BR-05403000 São Paulo, BrazilUniversidade Federal de São Paulo, Dept Morphol & Genet, BR-04023900 São Paulo, BrazilUniversidade Federal de São Paulo, Dept Biophys, BR-04023900 São Paulo, BrazilUniversidade Federal de São Paulo, Dept Pathol, Lab Citogenom, BR-05403000 São Paulo, BrazilFAPESP: 2012/51150-0FAPESP: 2012/15572-7Web of Scienc

Allan-Herndon-Dudley syndrome in a female patient and related mechanisms.

peer reviewedAllan-Herndon-Dudley syndrome (AHDS) is characterized by neuropsychomotor developmental delay/intellectual disability, neurological impairment with a movement disorder, and an abnormal thyroid hormone profile. This disease is an X-linked disorder that mainly affects men. We described a female patient with a de novo variant in the SLC16A2 gene, a milder AHDS phenotype, and a skewed X chromosome inactivation profile. We discuss the mechanisms associated with the expression of the phenotypic characteristics in female patients, including SLC16A2 gene variants and cytogenomic alterations, as well as preferential inactivation of the normal X chromosome

Duplication 9p and their implication to phenotype

Background: Trisomy 9p is one of the most common partial trisomies found in newborns. We report the clinical features and cytogenomic findings in five patients with different chromosome rearrangements resulting in complete 9p duplication, three of them involving 9p centromere alterations.Methods: the rearrangements in the patients were characterized by G-banding, SNP-array and fluorescent in situ hybridization (FISH) with different probes.Results: Two patients presented de novo dicentric chromosomes: der(9; 15)t(9; 15)(p11.2;p13) and der(9; 21)t(9; 21) (p13.1;p13.1). One patient presented two concomitant rearranged chromosomes: a der(12)t(9; 12)(q21.13;p13.33) and an psu i(9)(p10) which showed FISH centromeric signal smaller than in the normal chromosome 9. Besides the duplication 9p24.3p13.1, array revealed a 7.3 Mb deletion in 9q13q21.13 in this patient. the break in the psu i(9) (p10) probably occurred in the centromere resulting in a smaller centromere and with part of the 9q translocated to the distal 12p with the deletion 9q occurring during this rearrangement. Two patients, brother and sister, present 9p duplication concomitant to 18p deletion due to an inherited der(18)t(9; 18)(p11.2; p11.31) mat.Conclusions: the patients with trisomy 9p present a well-recognizable phenotype due to facial appearance, although the genotype-phenotype correlation can be difficult due to concomitant partial monosomy of other chromosomes. the chromosome 9 is rich in segmental duplication, especially in pericentromeric region, with high degree of sequence identity to sequences in 15p, 18p and 21p, chromosomes involved in our rearrangements. Thus, we suggest that chromosome 9 is prone to illegitimate recombination, either intrachromosomal or interchromosomal, which predisposes it to rearrangements, frequently involving pericentromeric regions.Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Universidade Federal de São Paulo, Dept Morphol & Genet, BR-04023900 São Paulo, BrazilUniv São Paulo, Dept Pathol, Lab Citogen, BR-05403000 São Paulo, BrazilUniversidade Federal de São Paulo, Dept Morphol & Genet, BR-04023900 São Paulo, BrazilFAPESP: 2012/51150-0FAPESP: 2012/15572-7Web of Scienc

Mechanisms of ring chromosome formation, ring instability and clinical consequences

<p>Abstract</p> <p>Background</p> <p>The breakpoints and mechanisms of ring chromosome formation were studied and mapped in 14 patients.</p> <p>Methods</p> <p>Several techniques were performed such as genome-wide array, MLPA (Multiplex Ligation-Dependent Probe Amplification) and FISH (Fluorescent <it>in situ </it>Hybridization).</p> <p>Results</p> <p>The ring chromosomes of patients I to XIV were determined to be, respectively: r(3)(p26.1q29), r(4)(p16.3q35.2), r(10)(p15.3q26.2), r(10)(p15.3q26.13), r(13)(p13q31.1), r(13)(p13q34), r(14)(p13q32.33), r(15)(p13q26.2), r(18)(p11.32q22.2), r(18)(p11.32q21.33), r(18)(p11.21q23), r(22)(p13q13.33), r(22)(p13q13.2), and r(22)(p13q13.2). These rings were found to have been formed by different mechanisms, such as: breaks in both chromosome arms followed by end-to-end reunion (patients IV, VIII, IX, XI, XIII and XIV); a break in one chromosome arm followed by fusion with the subtelomeric region of the other (patients I and II); a break in one chromosome arm followed by fusion with the opposite telomeric region (patients III and X); fusion of two subtelomeric regions (patient VII); and telomere-telomere fusion (patient XII). Thus, the r(14) and one r(22) can be considered complete rings, since there was no loss of relevant genetic material. Two patients (V and VI) with r(13) showed duplication along with terminal deletion of 13q, one of them proved to be inverted, a mechanism known as inv-dup-del. Ring instability was detected by ring loss and secondary aberrations in all but three patients, who presented stable ring chromosomes (II, XIII and XIV).</p> <p>Conclusions</p> <p>We concluded that the clinical phenotype of patients with ring chromosomes may be related with different factors, including gene haploinsufficiency, gene duplications and ring instability. Epigenetic factors due to the circular architecture of ring chromosomes must also be considered, since even complete ring chromosomes can result in phenotypic alterations, as observed in our patients with complete r(14) and r(22).</p

Chromosome 18p deletion syndrome: Clinical and cytogenomic characterisation.

Chromosome 18p deletion syndrome [del(18p)] (OMIM 146390) has been well described in the literature with over 300 patients reported on, but few of them evaluated by cytogenomic techniques. Objective: We studied 12 patients with 18p deletion based on clinical, developmental and cytogenomic findings. Methods: The patients were evaluated by a specific clinical protocol, including immunological, endocrinological and neuropsychological assessments. The cytogenetic study was performed by G-banding karyotype, SNP-array (Genome-Wide Human SNP Array 6.0, Affymetrix) and FISH-BAC techniques. Results: A total of 12 patients, seven males and five females, previously diagnosed with 18p deletion were evaluated. The patients were classified in three groups according to the cytogenomic findings, as follows: five with pure 18p deletion (group I), two with ring chromosome 18 (group II) and five with 18p deletion associated with duplication or deletion of another chromosome (group III). Conclusions: The results showed a wide variation in intra- and inter-chromosomal rearrangements in patients, both inherited as de novo, as well as a wide variability of phenotypic manifestations and comorbidities. Although the literature indicates 18p11.1 as the most frequent breakpoint, our patients presented different breakpoints: 18p11.21 (5/12), 18p11.23 (2/12), 18p11.31 (4/12), and 18p11.32 (1/12). The main clinical findings were: proportionate short stature; microcephaly; ectopic pituitary; growth hormone deficiency; hypothyroidism; intellectual disability; cardiac anomalies; scoliosis; and keratosis pilaris. The distinguished facial dysmorphic features were: ocular hypertelorism; ptosis; and strabismus.The neuropsychological assessments showed IQ scores from borderline intellectual functioning to moderate intellectual disability. The SNP-array technique permitted a better chromosome breakpoint definition and, associated to the specific clinical protocol, provided a better genotype-phenotype correlation revealing genes that might influence the patient?s phenotype. Some genes located in the 18p deleted segment seem to play important roles in the patient?s phenotype, such as TGIF1, GNAL, LAMA1 and LPIN2 genes. The clinical protocol associated with cytogenomic results provided the recognition of relevant genes to the clinical manifestations found, such as holoprosencephaly microforms, keratosis pilaris, cryptorchidism, scoliosis and IgA deficiency. In addition, the multidisciplinary approach of this study allowed making recommendations for medical and neuropsychological evaluation on 18p deletion patients for better clinical monitoring and appropriate genetic counseling for each family.Avaliar uma amostra de pacientes com deleção 18p, sob os aspectos clínicos e citogenômicos a fim de aprimorar a correlação genótipo-fenótipo. Métodos: Os pacientes foram avaliados por meio de protocolo clínico específico, desenvolvido a partir da revisão da literatura, e de avaliações imunológica e neuropsicológica. Uma planilha de dados foi criada no programa Microsoft Excel com os achados clínicos, exames complementares, citogenômicos e avaliações neuropsicológica e imunológica para facilitar a realização da correlação genótipo-fenótipo. O estudo citogenômico foi realizado por cariotipagem sob bandamento G, técnicas de array genômico e de FISH (do inglês, Fluorescent In Situ Hybridization). Resultados e Conclusões: Foram estudados 12 pacientes diagnosticados previamente com deleção 18p, sendo sete do sexo masculino e cinco do sexo feminino. Os pacientes foram classificados em três grupos em função dos achados citogenômicos encontrados, sendo: cinco com deleção 18p pura (grupo I), dois com cromossomo 18 em anel (grupo II) e cinco com deleção 18p associada à duplicação ou deleção de outro cromossomo (grupo III). Os resultados revelaram grande variação de rearranjos intra e inter-cromossômicos nos pacientes, tanto herdados quanto de novo, assim como grande variabilidade de manifestações fenotípicas e comorbidades associadas. O estudo por array genômico permitiu a determinação mais acurada dos pontos de quebra e uma melhor correlação genótipo-fenótipo. A análise por FISH foi importante para a investigação da presença de translocação equilibrada nos pais dos pacientes. O protocolo clínico associado ao estudo citogenômico dos pacientes proporcionou o reconhecimento de genes relevantes para as manifestações clínicas encontradas tais como o espectro da holoprosencefalia, baixa estatura, queratose pilar, criptorquidia, escoliose e deficiência de IgA. Além disso, esta abordagem multidisciplinar permitiu a criação e proposição de recomendações para a avaliação médica e neuropsicológica de pacientes com deleção 18p, de forma a proporcionar um melhor seguimento clínico e aconselhamento genético adequado para cada família.Dados abertos - Sucupira - Teses e dissertações (2013 a 2016)Fundação de Amparo à Pesquisa do Estado de São Paulo ­ (FAPESP)FAPESP: 2010/50737­

CEDNIK syndrome in a Brazilian patient with compound heterozygous pathogenic variants.

peer reviewedCEDNIK (Cerebral Dysgenesis, Neuropathy, Ichthyosis, and Keratoderma) syndrome is a neuro ichthyotic syndrome characterized by a clinical constellation of features including severe developmental delay, microcephaly, and facial dysmorphism. Here, we report the clinical and molecular characterization of a patient with CEDNIK syndrome harboring two compound heterozygous variants in the SNAP29 gene. The patient presents a combination of a loss-of-function SNAP29 mutation and a ∼370 kb 22q11.2 deletion, each of these genetic variants inherited from one of the parents. This report provides detailed data of a patient with unprecedented genetic events leading to the CEDNIK phenotype and may contribute to the elucidation of this rare condition