Development of On-DNA Cyclic Imide Synthesis for DNA Encoded Library Construction.

Here, we describe a novel method for the on-DNA synthesis of cyclic imides, an important class of molecules that includes several well-known medications. Significantly, the new method enabled on-DNA synthesis under mild conditions with high conversions and a broad functional group tolerance, utilizing ubiquitous bifunctional amines and bis-carboxylic acid, or alkyl halides, and therefore served as the linchpin for DNA encoded library (DEL) synthesis. The mechanism study of off-DNA and on-DNA chemical transformations revealed unique insights in contrast to conventional chemical transformation.

Retinal dystrophy associated with a single-base deletion mutation in mitochondrial DNA 3271 in patient with MELAS syndrome.

PURPOSE: Mitochondrial encephalopathy with lactic acid and stroke-like episodes (MELAS) is caused by mutations in the mitochondrial DNA. Approximately 80% of MELAS patients have an A > G transition mutation at nucleotide pair 3243 in the mitochondrial DNA, m.3243A > G. There are also MELAS patients with a one-base deletion at nucleotide pair 3271 in the mitochondrial DNA, m.3271delT, but these cases are very rare. We report a case of MELAS with the m.3271delT and describe the retinal structure and electrophysiological alterations. METHODS: The retinal structure and function of a 37-year-old woman who was referred to our clinic for of nyctalopia were studied. Standard ophthalmological examinations including the medical history, measurements of the best-corrected visual acuity, intraocular pressures, and slit-lamp biomicroscopy, ophthalmoscopy, fluorescein angiography, fundus autofluorescence, spectral-domain optical coherence tomography (SD-OCT), full-field electroretinography (ERG), and multifocal electroretinography (mfERG) were performed. RESULTS: Fundus examination showed bilateral hypopigmentary changes of the retinal pigment epithelium which extended from the posterior pole to the equator. Fluorescein angiography showed patchy hyperfluorescence due to window defects at the atrophic areas. Fundus autofluorescence demonstrated mild hyperfluorescent lesions in both eyes. SD-OCT showed that the interdigitation zone was indistinct in both eyes, and the inner nuclear layer was slightly thinner. The amplitudes of the rod, cone, and 30-Hz flicker ERGs were severely reduced, and the implicit times were prolonged. The a- and b-waves of the bright-flash mixed rod-cone ERGs were also reduced. The dark-adapted oscillatory potentials were reduced. The amplitudes of the mfERGs were severely depressed except at the fovea in both eyes. CONCLUSIONS: These findings indicate that the RPE atrophy was wider and the rod dysfunction was more severe affected than that of previously reported MELAS cases with the m.3243A > G mutation.

Identification of a Rare ß(0)-Thalassemia Mutation, Codon 54 (-T) (HBB: c.165delT) in an Iranian Family.

ß-Thalassemia (ß-thal) is the most widespread autosomal recessive disorder worldwide. The present study describes a very rare ß-globin gene mutation, codon 54 (-T) (HBB: c.165delT), in a family from northern Iran. Nucleotide sequencing of amplified DNA obtained from a 28-year-old man revealed a deletion (-T) at codon 54 of the ß-globin gene that results in a nonsense sequence at codon 60 and inphase termination at codon 59. Moreover, the haplotype combination of six different restriction enzyme sites in the ß-globin cluster was determined for this mutation. To the best of our knowledge, this is the second article reporting the codon 54 mutation worldwide and the first report of this mutation in the Iranian population, emphasizing the high heterogeneity of this population.

[Cases Analysis of Hemoglobin H Disease Caused by HBA2:c.2T>C and HBA2:c.2delT Mutations].

OBJECTIVE: To investigate two cases of rare pathogenic genes, initiation codon mutations in HBA2 gene, combined with Southeast Asian deletion and their family members to understand the relationship of HBA2:c.2T>C and HBA2:c.2delT mutations with clinical phenotype. METHODS: The peripheral blood of family members was obtained for blood cell analysis and capillary electrophoresis hemoglobin analysis. Gap-PCR and reverse dot blotting (RDB) were used to detect common types of mutations in ɑ-thalassaemia gene. Sanger sequencing was used to analyze HBA1 and HBA2 gene sequence. RESULTS: Two proband genotypes were identified as --SEA/αα with HBA2:c.2T>C and --SEA/αα with HBA2:c.2delT. HBA2:c.2T>C/WT and HBA2:c.2delT/WT was detected in family members. They all presented with microcytic hypochromic anemia. CONCLUSION: When HBA2:c.2T>C and HBA2:c.2delT are heterozygous that can lead to static α-thalassemia phenotype, and when combined with mild α-thalassemia, they can lead to the clinical manifestations of hemoglobin H disease. This study provides a basis for genetic counseling.

Two children with hypophosphatasia with a heterozygous c.1559delT variant in the ALPL gene, the most common variant in Japanese populations.

Hypophosphatasia (HPP), a genetic disorder characterized by decreased tissue-nonspecific alkaline phosphatase (TNSALP) activity, is caused by loss-of-function mutations in the ALPL gene, which encodes TNSALP. The most frequent pathogenic variant in Japanese patients with HPP is a frameshift mutation in the ALPL gene, c.1559delT, and its carrier frequency is reported to be one in 480 in the Japanese population. We report the cases of two Japanese children with HPP who had a heterozygous c.1559delT variant in the ALPL gene. One case (involving a neonate) exhibited respiratory insufficiency associated with vitamin B6 dependent convulsions, significant defective mineralization similar to the severe form of HPP, and extremely low ALP activity. Enzyme replacement therapy (ERT) using asfotase alfa promptly improved her respiratory insufficiency, bone mineralization, and maintained her motor development during infancy. The second case involved a 10-year-old boy who demonstrated diffuse musculoskeletal pain and weakness that progressively disturbed mobility. Although he showed no bony lesions, the clinical symptoms and biochemical abnormalities were compatible with childhood HPP. ERT successfully relieved the severe generalized pain and significantly improved motor function.

Sporadic Triple A (Allgrove) Syndrome with Novel Tandem Mutations.

In triple A (Allgrove) syndrome, motor neuron disease is a co-morbid condition. We herein report a 38-year-old Japanese man with triple A (Allgrove) syndrome and novel tandem mutations: a novel c.881delT deletion mutation and c.835C>T localized to the AAAS gene. A nerve conduction study revealed marked axonal damage in several motor nerves. Tandem mutations in the AAAS gene may be involved in co-morbid motor neuron disease and aberrant electrophysiological findings.

A novel compound heterozygous mutation of SLC12A3 gene in a Chinese pedigree with Gitelman syndrome.

PURPOSE: Gitelman syndrome (GS) is an autosomal recessive renal tubular disorder characterized by salt wasting and hypokalemia resulting from loss-of-function mutations in the solute carrier family 12A3 (SLC12A3) gene encoding the thiazide-sensitive NaCl cotransporter (NCC). Here, we investigated the clinical manifestations and genetic features of a Chinese pedigree with GS. METHODS: Next-generation sequencing and Sanger sequencing analysis were performed to define and confirm the SLC12A3 gene mutations of the patient (proband II:1) and this pedigree. Clinical manifestations and biochemical parameters were collected and analyzed. RESULTS: Genetic analysis of the SLC12A3 gene identified two novel mutations in the proband, heterozygous (c.2842delT) and heterozygous (c.1569_1586del) mutation, respectively. Additionally, heterozygous (c.2842delT) mutation in SLC12A3 gene was found in his father and younger brother. The other heterozygous (c.1569_1586del) mutation in SLC12A3 gene was carried by his mother. CONCLUSIONS: Two novel mutations may be related to the occurrence of the GS in the pedigree. However, additional studies are particularly required to explore the underlying molecular mechanisms.

Disseminated Medulloblastoma in a Child with Germline BRCA2 6174delT Mutation and without Fanconi Anemia.

Medulloblastoma, the most common malignant brain tumor in children, occurs with increased frequency in individuals with Fanconi anemia who have biallelic germline mutations in BRCA2. We describe an 8-year-old child who had disseminated anaplastic medulloblastoma and a deleterious heterozygous BRCA2 6174delT germline mutation. Molecular profiling was consistent with Group 4 medulloblastoma. The posterior fossa mass was resected and the patient received intensive chemotherapy and craniospinal irradiation. Despite this, the patient succumbed to a second recurrence of his medulloblastoma, which presented 8 months after diagnosis as malignant pleural and peritoneal effusions. Continuous medulloblastoma cell lines were isolated from the original tumor (CHLA-01-MED) and the malignant pleural effusion (CHLA-01R-MED). Here, we provide their analyses, including in vitro and in vivo growth, drug sensitivity, comparative genomic hybridization, and next generation sequencing analysis. In addition to the BRCA2 6174delT, the medulloblastoma cells had amplification of MYC, deletion at Xp11.2, and isochromosome 17, but no structural variations or overexpression of GFI1 or GFI1B. To our knowledge, this is the first pair of diagnosis/recurrence medulloblastoma cell lines, the only medulloblastoma cell lines with BRCA2 6174delT described to date, and the first reported case of a child with medulloblastoma associated with a germline BRCA2 6174delT who did not also have Fanconi anemia.

Monitoramento da suscetibilidade ao piretróide Deltametrina em populações de Triatoma sordida Stål, 1859 (Hemiptera: Reduviidae)

A resistência de triatomíneos a inseticidas já foi relatada na Venezuela, Argentina e Bolívia, sendo possível a existência de out ros focos em regiões ainda mais amplas. Deste modo, torna-se necessário desenv olver estudos que investiguem a dispersão geográfica desses vet ores resistentes, bem como os mecanismos envolv idos, com vistas a elaborar estratégias adequadas às necessidades locais , ou até mesmo que impeçam o aparecimento deste fenômeno. O objetivo deste estudo foi padronizar ensaios biológicos para monitoramento de resistência de triatomíneos a inseticidas em laborat ório e caracterizar a su scetibilidade de quat orze populações de Tri atom a sordida Stal, 1859 de Minas Gerais (Sudest e do Bras il) ao piretróide Deltametrina. A área em que os triatomíneos foram coletados foi submetida ao controle químico por cerca de 30 anos. A linhagem referência de suscetibilid ade é oriunda de Uberaba. A metodologia foi orientada pelas recom endações da WHO (1994) e OPS (2005), tendo sido redefinidos alguns detalhes técnicos (dose diagnóstica adequada para triagem de resistência em triatomíneos, lo cal ideal de aplicaçã o do ins eticida nas ninfas I, idade e gera ção dos in setos utiliz ados). A linha base d e suscetibilidade da linhagem r eferência f oi inic ialm ente det erminada. A Deltametrina, solubilizada em acetona, foi aplicada topica ment e no dorso do abdômen de ninf as I da ger ação F 2 (cinco dias de idade, j ejum, ± 1,2 mg. de pes o) com auxílio de um a microseringa. Os resultados dos ensaios dose-resposta foram analisados com auxílio do programa PROBIT (Finney, 1971). Em seguida, as populações de campo foram submetidas a dose diagnóstica de 1XDL99 da linhagem re ferência de s uscetibi lidade e 2XDD99 da linhagem referência de susc etibilidad e. Todas as populações apresentaram-se menos sus cetíveis ao insetic ida quando co mparadas com a linhagem referência de suscetibilidade. As razões de r esistência encontradas variaram de 2,6 a 6,8. A comparação de um fragmento de DNA de 317 pb do gene mitocondrial do citocromo b (mtCytB) foi usada para inferir sobr e a varia bilidade genética das quatorze populações de T. sordida estudadas. Inferências filogenéticas, usando P. megistu s como grupo externo, não revelaram a formação de clados. O s 150 es pécimes analisados apresentaram 50 haplótipos gerando uma divers idade (Hd) de 0,831. Foi possível distinguir seis populaçõ es genet icamente diferentes. Anális e do Network revelou a presença de vários loops , demonstrando homoplas ia e a ocorrência de mutações reversas/paralelas. Com o ma rcador genético utiliz ado não foi possível estabelecer correlação entre a variabilid ade genética das populaç ões estudadas e a resistência a Deltametrina. Giordano et al. (2005) sugerem que os microssatélites podem ser uma ferramenta mais sensível e eficiente para este objetivo. A possível natureza bioquímica da resistência encontrada está sendo verificada.