cGAS guards against chromosome end-to-end fusions during mitosis and facilitates replicative senescence

As a sensor of cytosolic DNA, the role of cyclic GMP-AMP synthase (cGAS) in innate immune response is well established, yet how its functions in different biological conditions remain to be elucidated. Here, we identify cGAS as an essential regulator in inhibiting mitotic DNA double-strand break (DSB) repair and protecting short telomeres from end-to-end fusion independent of the canonical cGAS-STING pathway. cGAS associates with telomeric/subtelomeric DNA during mitosis when TRF1/TRF2/POT1 are deficient on telomeres. Depletion of cGAS leads to mitotic chromosome end-to-end fusions predominantly occurring between short telomeres. Mechanistically, cGAS interacts with CDK1 and positions them to chromosome ends. Thus, CDK1 inhibits mitotic non-homologous end joining (NHEJ) by blocking the recruitment of RNF8. cGAS-deficient human primary cells are defective in entering replicative senescence and display chromosome end-to-end fusions, genome instability and prolonged growth arrest. Altogether, cGAS safeguards genome stability by controlling mitotic DSB repair to inhibit mitotic chromosome end-to-end fusions, thus facilitating replicative senescence.

Heterogeneous phenotypes, genotypes, treatment and prevention of 1 003 patients with methylmalonic acidemia in the mainland of China / 中华儿科杂志

Objective@#To analyz the current situation of the diagnosis, treatment and prevention of methylmalonic acidemia, the phenotypes, biochemical features and genotypes of the patients in the mainland of China, were investigated.@*Methods@#Tottally 1 003 patients of methylmalonic acidemia from 26 provinces and municipalities of the mainland of China were enrolled. The clinical data, biochemical features and gene mutations were studied. Blood aminoacids and acylcarnitines, urine organic acids, and plasma total homocysteine were determined for the biochemical diagnosis. Gene analyses were performed for the genetic study of 661 patients. The patients were treated with individual intervention and long-term follow up. Prenatal diagnoses were carried out for 165 fetuses of the families.@*Results@#Among 1 003 patients (580 boys and 423 girls), 296 cases (29.5%) had isolated methylmalonic acidemia; 707 cases (70.5%) had combined homocysteinemia; 59 patients (5.9%) were detected by newborn screening; 944 patients (94.1%) had the onset at the ages from several minutes after birth to 25 years and diagnosed at 3 days to 25 years of age. The main clinical presentations were psychomotor retardation and metabolic crisis. Multi-organ damage, including hematological abnormalities, pulmonary hypertension, kidney damage, were found. MMACHC, MUT, MMAA, MMAB, HCFC1, SUCLG1, SUCLA2 mutations were found in 631 patients (96.6%) out of 661 patients who accepted gene analysis. MMACHC mutations were detected in 460 patients (94.7%) out of 486 cases of methylmalonic acidemia combined with homocysteinemia. MUT mutations were found in 158 (90.3%) out of 169 cases of isolated methylmalonic acidemia. The development of 59 patients detected by newborn screening were normal; 918 cases (97.2%) were diagnosed after onset accepted the treatment. Forty-five of them completely recovered with normal development. Twenty-six patients (2.7%) died; 873 (92.5%) patients had mild to severe psychomotor retardation. Methylmalonic acidemia were found in 35 out of 165 fetuses by metabolites assay of amniotic fluid and amniocytes gene analysis.@*Conclusion@#Combined methylmalonic acidemia and homocysteinemia is the common type of methylmalonic acidemia in the mainland of China. CblC defect due to MMACHC mutations is the most common type of methylmalonic acidemia combined with homocysteinemia. MUT gene mutations are frequent in the patients with isolated methylmalonic acidemia. Newborn screening is key for the early diagnosis and the better outcome. Combined diagnosis of biochemical assays and gene analysis are reliable for the prenatal diagnosis of methylmalonic acidemia.

A pedigree of a rare Cb1X type X-linked methylmalonic acidemia due to transcriptional co-regulator HCFC1 ;mutation / 临床儿科杂志

Objective To explore the clinical and genetic features in the pedigree of Cb1X type X-linked methylmalonic aciduria. Methods Clinical data of one child with X-linked methylmalonic aciduria diagnosed by blood and urine analysis were analyzed retrospectively. Targeted next-generation sequencing has been performed to detect the mutation of methylmalonic aciduria-related genes. Results The boy started presenting with seizures and severe mental retardation at 2 months of age. At 5 months of age, he had the manifestations of seizures, severe mental retardation, increased methylmalonic acid in urinary, increased propionylcarnitine in blood and increased plasma homocysteine, and met the requirements for the diagnosis of methylmalonic aciduria complicated with hyperhomocysteinemia. No mutation was detected in his MMA-related autosomal genes. However, a hemizygote mutation c.344C?>?T (p.Ala115Val) was identiifed in exon 3 of HCFC1 in X chromosome, which conifrmed the CblX type methylmalonic aciduria. His parents were healthy. His elder brother also manifested severe psychomotor retardation with intractable epilepsy, and died at 6 months of age with unknown cause. His mother carried the same mutation and had slightly elevated urine methylmalonic acid and plasma total homocysteine. His father did not carry the mutation. Conclusion A pedigree of a rare Cb1X type X-linked methylmalonic acidemia is ifrstly diagnosed in China by the new generation sequencing technology.

Phenotypes and genotypes of 126 patients with isolated methylmalonic aciduria / 中华实用儿科临床杂志

Objective To investigate the clinical,biochemical and genetic findings in patients with isolated methylmalonic aciduria. Methods From January 2001 to December 2014,a total of 126 patients with isolated methyl-malonic aciduria from Peking University First Hospital were enrolled in this study. In 60 patients,gene analysis was per-formed. The clinical characteristics,laboratory findings,treatment and outcomes were retrospectively analyzed. Results Among the 126 patients,only 3 cases(2. 4% )were detected through newborn screening and treated with dietary in-tervention,cobalamin and L - camitine. The age at onset of 123 cases(97. 6% )varied from a few hours after birth to 7 years and 11 months old. The common presentations were recurrent vomiting,mental retardation,poor feeding,lethargy, respiratory distress,coma,seizures,cutaneous lesion and jaundice with 11 patients(8. 73% )dead. Abnormal family his-tory was found in 27(21. 4% )patients. Metabolic acidosis and anemia were frequent laboratory findings. Basal ganglia damage and white matter changes were observed in most patients. Sixty patients got genetic analysis,and 58 cases of them had MUT gene mutations. One case had MMAA defect. One case had MMAB defect. In MUT gene,12 novel muta-tions were identified. After treatment,mild to severe psychomotor retardation was observed in 112 patients with isolated methylmalonic aciduria. Conclusions The clinical manifestation of patients with isolated methylmalonic aciduria is complex,and prone to appear metabolic crisis. MUT defect is the main cause. Early metabolic investigation is very im-portant to reach diagnosis. Newborn screening,early diagnosis and adequate therapy are key points to reduce the morta-lity and handicap.

Seven patients of argininemia with spastic tetraplegia as the first and major symptom and prenatal diagnosis of two fetuses with high risk / 中华儿科杂志

<p><b>OBJECTIVE</b>Argininemia is a rare disorder of urea cycle defect. The clinical manifestations of this disorder are similar to those of cerebral palsy so that the diagnosis is usually much delayed. This study aimed to investigate the phenotypes and genotypes of seven Chinese patients suffering from argininemia.</p><p><b>METHOD</b>Three boys and four girls with spastic tetraplegia were diagnosed as argininemia by blood aminoacids analysis and ARG1 gene study. Patients were given a protein-restricted diet, citrulline, sodium benzoate, and other treatment intervention. The mother of Patient 5 and 6 accepted genetic counseling and underwent prenatal diagnosis by amniocentesis.</p><p><b>RESULT</b>Seven patients presented with progressive spastic tetraplegia and poor physical growth from the age of 1 month to 4 years. Argininemia was found at the age of 1 year and 10 months to 12 years. Five patients had mental retardations. Three had seizures. Their blood arginine elevated (86.66 to 349.83 µmol/L, normal controls 5 to 25 µmol/L). Liver dysfunction was found in six patients. Five patients had elevated blood ammonia levels. In four patients, cerebral atrophy was observed by cranial magnetic resonance imaging. Nine mutations in the ARG1 gene were identified from 7 patients. Only two mutations, c.703G > A in exon 7 and c.32T > C in exon 1 had been reported. c.34G > T, c.53G > A, c.67delG, c.232dupG, c.374C > T, c.539G > C and c.646-649delCTCA, were novel mutations of ARG1. A homozygous mutation c.703G > A was found in the amniocytes of Patient 5's mother, indicating that the fetus was affected by argininemia. Induced abortion was performed. c.53G > A from Patient 6 was not found in the amniocytes of her mother, indicating that the fetus was not affected by hepatocyte arginase deficiency. The result was confirmed by postnatal mutation analysis of cord blood and the normal blood arginine of the newborn.</p><p><b>CONCLUSION</b>Argininemia is one of the few treatable causes of pediatric spastic paralysis. In this study, seven Chinese patients with spastic tetraplegia were detected by blood aminoacids analysis and confirmed by molecular analysis. Seven novel mutations on ARG1 gene were identified. Prenatal diagnosis of the fetus of a family was performed by amniocytes ARG1 gene analysis.</p>

Clinical and genetic features of three patients with non-classical isovaleric aciduria / 临床儿科杂志

Objective To explore the clinical, therapeutic and genetic features of IVD gene in late-onset non-classical isovaleric aciduria. Methods One boy and two girls presented with intractable vomiting were admitted. Urine organic acids and blood acylcarnitines proifles were analyzed. Isovaleric aciduria was diagnosed and conifrmed by IVD gene analysis. The patients were treated with leucine-restricted diet and the supplements of L-carnitine and glycine. Results Three patients had recurrent vomiting, drowsiness, odor of sweaty feet and metabolic acidosis from the age of 1 to 2 years. All of them had normal intelligence and leukopenia. One had oligocythemia. The blood isovalerylcarnitines (4.6 to 8.2μmol/L) and urine isovalerylglycines (36.1 to 1783.56 mmol/mmol creatinine) were elevated. Six mutations were found in their IVD gene. Four mutations (c.157C>T, c.214G>A, c.1183C>G and c.1208A>G) were reported. Two (c.1039G>A and c.1076A>G) were novel. The patients completely recovered after treatment with protein-restricted diet and the supplements of L-carnitine and glycine. Currently, they were aged 19 months to 14 years with normal physical and psychomotor development. Conclusions The clinical features of late-onset non-classical isovaleric aciduria are complex. It is onset in infants and young children and characteristic of recurrent vomiting and metabolic acidosis, which can be diagnosed by the blood acylcarnitine spectrum, urine organic acid analysis, and conifrmed by genetic analysis. L-carnitine supplement and diet intervention has signiifcant effects.

Screening for antiviral fractions from ethanol extract of Euphorbia Kansui Liou / 中成药

Objective: To elucidate antiviral fractions from ethanol extract of Euphorbia kansui .Methods: Initial separation of ethanol extract from Euphorbia kansui was performed by column chromatography. The test mice were infected with flu virus mouse pneumonia adaptive strain (FM 1) and then treated with separated fractions intragastrally for determining lung index inhibition rate. The T lymphocyte proliferation enhancement was observed by the dosimetry of 3 H TdR infiltrated into DNA of the cell.Result: Initial separation of the extract afforded to 15 fractions. Fractions 8～15 with the elution volume from 29500 to 95000mL were highly effective to the therapy of the mice pneumonia. The enhancement to the lymphocyte proliferation of the 8 fractions under low concentration were 2～3 times higher than that of the control.Conclusion: Fractions 5 and 8～15 exhibited strong in vivo antiviral activity to the test virus, which might be realized by stimulating lymphocyte proliferation, enhancing the capacity of killing the cells infected by the virus.