GUILHERME LOPES YAMAMOTO
Projetos de Pesquisa
Unidades Organizacionais
Instituto da Criança, Hospital das Clínicas, Faculdade de Medicina - Médico
LIM/36 - Laboratório de Pediatria Clínica, Hospital das Clínicas, Faculdade de Medicina
LIM/36 - Laboratório de Pediatria Clínica, Hospital das Clínicas, Faculdade de Medicina
6 resultados
Resultados de Busca
Agora exibindo 1 - 6 de 6
- Intragenic Deletion in the LIFR Gene in a Long-Term Survivor with Stuve-Wiedemann Syndrome(2015) MARQUES, Julia Hatagami; YAMAMOTO, Guilherme Lopes; TESTAI, Larissa de Cassia; PEREIRA, Alexandre da Costa; KIM, Chong Ae; PASSOS-BUENO, Maria R.; BERTOLA, Debora RomeoStuve-Wiedemann syndrome (SWS, OMIM 601559) is a rare autosomal recessive bent-bone dysplasia, caused by loss-offunction mutations in the leukemia inhibitory factor receptor (LIFR) gene, which usually leads to early death. Only few patients with long-term survival have been described in the literature. We report on a 5-year-old boy from a consanguineous marriage with molecular analysis for the LIFR gene. Sanger and next-generation sequencing (NGS) of LIFR were performed. Copy number variation analysis with NGS showed a novel mutation as the cause for the syndrome: an intragenic homozygous deletion in LIFR, involving exons 1520. Bridging PCR was carried out to confirm the intragenic deletion. This is the first description of a large deletion in LIFR, broadening the spectrum of mutations in SWS. Besides the reported allelic heterogeneity, further studies such as exome sequencing are required to identify a novel gene in order to confirm the locus heterogeneity in SWS. (C) 2015 S. Karger AG, Basel
- A dopamine receptor D2 genetic polymorphism associated with transition to mental disorders in a cohort of individuals with at-risk mental state for psychosis(2023) MARQUES, Julia Hatagami; TALIB, Leda Leme; HORTENCIO, Lucas; ANDRADE, Julio Cesar; ALVES, Tania Maria; SERPA, Mauricio Henriques; YAMAMOTO, Guilherme Lopes; BILT, Martinus Theodorus van de; ROSSLER, Wulf; GATTAZ, Wagner Farid; LOCH, Alexandre AndradeObjectives: To test the association of 45 single nucleotide polymorphisms (SNPs) with transition to psychiatric disorders in a cohort of individuals at ultrahigh risk (UHR) mental state for psychosis.Methods: Through general population screening, 88 non-help-seeking UHR subjects and 130 healthy control individuals were genotyped for 45 SNPs related to psychosis. They were followed for a mean of 2.5 years, and conversion to psychotic and to general psychiatric disorders was assessed. Genotype frequencies between controls, converters, and non-converters were analyzed.Results: There were no differences in sociodemographics between controls and UHR. Also, UHR converters and non-converters had no differences in their baseline symptoms scores. The dopamine receptor D2 gene (DRD2) SNP rs6277 was significantly more common among UHR who transitioned to psychosis (p o 0.001) and to UHR who transitioned to any psychiatric disorders (p = 0.001) when compared to UHR who did not transition. The rs6277 T allele was related to psychiatric morbidity in a dose-response fashion, being significantly more frequent in UHR converters than UHR non-converters and control subjects (p = 0.003).Conclusion: Our findings suggest that rs6277 could potentially constitute a genetic marker of transition to psychiatric disorders in subjects with at-risk mental states, warranting further investigation in larger samples.
- Manifesting carriers of X-linked myotubular myopathy Genetic modifiers modulating the phenotype(2020) SOUZA, Lucas Santos; ALMEIDA, Camila Freitas; YAMAMOTO, Guilherme Lopes; PAVANELLO, Rita de Cassia Mingroni; GURGEL-GIANNETTI, Juliana; COSTA, Silvia Souza da; ANEQUINI, Isabela Pessa; CARMO, Silvana Amanda do; WANG, Jaqueline Yu Ting; SCLIAR, Marilia de Oliveira; CASTELLI, Erick C.; OTTO, Paulo Alberto; ZANOTELI, Edmar; VAINZOF, MarizObjective To analyze the modulation of the phenotype in manifesting carriers of recessive X-linked myotubular myopathy (XLMTM), searching for possible genetic modifiers. Methods Twelve Brazilian families with XLMTM were molecularly and clinically evaluated. In 2 families, 4 of 6 and 2 of 5 manifesting female carriers were identified. These females were studied for X chromosome inactivation. In addition, whole-exome sequencing was performed, looking for possible modifier variants. We also determined the penetrance rate among carriers of the mutations responsible for the condition. Results Mutations in the MTM1 gene were identified in all index patients from the 12 families, being 4 of them novel. In the heterozygotes, X chromosome inactivation was random in 3 of 4 informative manifesting carriers. The disease penetrance rate was estimated to be 30%, compatible with incomplete penetrance. Exome comparative analyses identified variants within a segment of 4.2 Mb on chromosome 19, containing the killer cell immunoglobulin-like receptor cluster of genes that were present in all nonmanifesting carriers and absent in all manifesting carriers. We hypothesized that these killer cell immunoglobulin-like receptor variants may modulate the phenotype, acting as a protective factor in the nonmanifesting carriers. Conclusions Affected XLMTM female carriers have been described with a surprisingly high frequency for a recessive X-linked disease, raising the question about the pattern of inheritance or the role of modifier factors acting on the disease phenotype. We demonstrated the possible existence of genetic mechanisms and variants accountable for the clinical manifestation in these women, which can become future targets for therapies.
- Biallelic variants in DNA2 cause poikiloderma with congenital cataracts and severe growth failure reminiscent of Rothmund-Thomson syndrome(2023) LAZZARO FILHO, Ricardo Di; YAMAMOTO, Guilherme Lopes; SILVA, Tiago J.; ROCHA, Leticia A.; LINNENKAMP, Bianca D. W.; CASTRO, Matheus Augusto Araujo; BARTHOLDI, Deborah; SCHALLER, Andre; LEEB, Tosso; KELMANN, Samantha; UTAGAWA, Claudia Y.; STEINER, Carlos E.; STEINMETZ, Leandra; HONJO, Rachel Sayuri; KIM, Chong Ae; WANG, Lisa; ABOURJAILI-BILODEAU, Raphael; CAMPEAU, Philippe; WARMAN, Matthew; PASSOS-BUENO, Maria Rita; HOCH, Nicolas C.; BERTOLA, Debora RomeoRothmund-Thomson syndrome (RTS) is a rare, heterogeneous autosomal recessive genodermatosis, with poikiloderma as its hallmark. It is classified into two types: type I, with biallelic variants in ANAPC1 and juvenile cataracts, and type II, with biallelic variants in RECQL4, increased cancer risk and no cataracts. We report on six Brazilian probands and two siblings of Swiss/Portuguese ancestry presenting with severe short stature, widespread poikiloderma and congenital ocular anomalies. Genomic and functional analysis revealed compound heterozygosis for a deep intronic splicing variant in trans with loss of function variants in DNA2, with reduction of the protein levels and impaired DNA double-strand break repair. The intronic variant is shared by all patients, as well as the Portuguese father of the European siblings, indicating a probable founder effect. Biallelic variants in DNA2 were previously associated with microcephalic osteodysplastic primordial dwarfism. Although the individuals reported here present a similar growth pattern, the presence of poikiloderma and ocular anomalies is unique. Thus, we have broadened the phenotypical spectrum of DNA2 mutations, incorporating clinical characteristics of RTS. Although a clear genotype-phenotype correlation cannot be definitively established at this moment, we speculate that the residual activity of the splicing variant allele could be responsible for the distinct manifestations of DNA2-related syndromes.
- Large deletion in PIGL: a common mutational mechanism in CHIME syndrome?(2018) CERONI, Jose R. M.; YAMAMOTO, Guilherme L.; HONJO, Rachel S.; KIM, Chong A.; PASSOS-BUENO, Maria R.; BERTOLA, Debora R.CHIME syndrome is an extremely rare autosomal recessive multisystemic disorder caused by mutations in PIGL. PIGL is an endoplasmic reticulum localized enzyme that catalyzes the second step of glycosylphosphatidylinositol (GPI) biosynthesis, which plays a role in the anchorage of cell-surface proteins including receptors, enzymes, and adhesion molecules. Germline mutations in other members of GPI and Post GPI Attachment to Proteins (PGAP) family genes have been described and constitute a group of diseases within the congenital disorders of glycosylation. Patients in this group often present alkaline phosphatase serum levels abnormalities and neurological symptoms. We report a CHIME syndrome patient who harbors a missense mutation c.500T > C (p.Leu167Pro) and a large deletion involving the 5' untranslated region and part of exon 1 of PIGL. In CHIME syndrome, a recurrent missense mutation c.500T > C (p.Leu167Pro) is found in the majority of patients, associated with a null mutation in the other allele, including an overrepresentation of large deletions. The latter are not detected by the standard analysis in sequencing techniques, including next-generation sequencing. Thus, in individuals with a clinical diagnosis of CHIME syndrome in which only one mutation is found, an active search for a large deletion should be sought.
- Burden of Rare Copy Number Variants in Microcephaly: A Brazilian Cohort of 185 Microcephalic Patients and Review of the Literature(2024) TOLEZANO, Giovanna Cantini; BASTOS, Giovanna Civitate; COSTA, Silvia Souza da; FREIRE, Bruna Lucheze; HOMMA, Thais Kataoka; HONJO, Rachel Sayuri; YAMAMOTO, Guilherme Lopes; PASSOS-BUENO, Maria Rita; KOIFFMANN, Celia Priszkulnik; KIM, Chong Ae; VIANNA-MORGANTE, Angela Maria; JORGE, Alexander Augusto de Lima; BERTOLA, Debora Romeo; ROSENBERG, Carla; KREPISCHI, Ana Cristina VictorinoMicrocephaly presents heterogeneous genetic etiology linked to several neurodevelopmental disorders (NDD). Copy number variants (CNVs) are a causal mechanism of microcephaly whose investigation is a crucial step for unraveling its molecular basis. Our purpose was to investigate the burden of rare CNVs in microcephalic individuals and to review genes and CNV syndromes associated with microcephaly. We performed chromosomal microarray analysis (CMA) in 185 Brazilian patients with microcephaly and evaluated microcephalic patients carrying < 200 kb CNVs documented in the DECIPHER database. Additionally, we reviewed known genes and CNV syndromes causally linked to microcephaly through the PubMed, OMIM, DECIPHER, and ClinGen databases. Rare clinically relevant CNVs were detected in 39 out of the 185 Brazilian patients investigated by CMA (21%). In 31 among the 60 DECIPHER patients carrying < 200 kb CNVs, at least one known microcephaly gene was observed. Overall, four gene sets implicated in microcephaly were disclosed: known microcephaly genes; genes with supporting evidence of association with microcephaly; known macrocephaly genes; and novel candidates, including OTUD7A, BBC3, CNTN6, and NAA15. In the review, we compiled 957 known microcephaly genes and 58 genomic CNV loci, comprising 13 duplications and 50 deletions, which have already been associated with clinical findings including microcephaly. We reviewed genes and CNV syndromes previously associated with microcephaly, reinforced the high CMA diagnostic yield for this condition, pinpointed novel candidate loci linked to microcephaly deserving further evaluation, and provided a useful resource for future research on the field of neurodevelopment.