Correction of the pathogenic mutation in the G6PC3 gene by adenine base editing in mutant embryos / 中华血液学杂志

Objective: To determine whether the adenine base editor (ABE7.10) can be used to fix harmful mutations in the human G6PC3 gene. Methods: To investigate the safety of base-edited embryos, off-target analysis by deep sequencing was used to examine the feasibility and editing efficiency of various sgRNA expression vectors. The human HEK293T mutation models and human embryos were also used to test the feasibility and editing efficiency of correction. Results: ①The G6PC3(C295T) mutant cell model was successfully created. ②In the G6PC3(C295T) mutant cell model, three distinct Re-sgRNAs were created and corrected, with base correction efficiency ranging from 8.79% to 19.56% . ③ ABE7.10 could successfully fix mutant bases in the human pathogenic embryo test; however, base editing events had also happened in other locations. ④ With the exception of one noncoding site, which had a high safety rate, deep sequencing analysis revealed that the detection of 32 probable off-target sites was <0.5% . Conclusion: This study proposes a new base correction strategy based on human pathogenic embryos; however, it also produces a certain nontarget site editing, which needs to be further analyzed on the PAM site or editor window.

Severe Congenital Neutropenia Type 4: A Rare Disease Harboring a G6pc3 Gene Pathogenic Variant Particular to the Mexican Population

ABSTRACT Background: Severe congenital neutropenia type 4 (SCN4) is a rare autosomal recessive granulopoiesis disorder caused by G6PC3 gene pathogenic variants. The estimated prevalence is 1/10,000,000 people. Over 90% of patients present a syndromic form with variable multisystemic involvement, including congenital heart defects, increased visibility of superficial veins (IVSV), inflammatory bowel disease, and congenital urogenital defects as prominent symptoms. Objectives: The objective of the study was to study non-hematological phenotypic findings that suggest a clinical diagnosis of SCN4. Methods: We examined medical records of patients diagnosed with neutropenia from January 2000 to December 2020, selecting cases with non-hematologic manifestations for phenotypic description and G6PC3 gene sequencing. Results: We found 11 cases with non-hematologic features: congenital heart defects in 8, IVSV in 6, inflammatory bowel disease in 4, urogenital defects in 4, and similar facial appearance. In addition, Sanger sequencing confirmed 3 homozygous cases for the c.210delC variant, a compound heterozygous harboring this variant, and a c.199_218+1 deletion. Conclusions: Our findings of the c.210delC variant in very close geographical settings, to date, have only been reported among Mexicans, and a mutual uncommon surname in two families strongly supports a founder effect for the variant in the studied population. Furthermore, the described non-hematologic symptoms in patients with severe primary neutropenia should be explored, confirming SCN4 by investigating G6PC3 gene mutations.

Neutropenia congênita / Congenital neutropenia

Buscamos aqui revisar os mecanismos imunopatológicos relacionados à neutropenia congênita.O termo neutropenia congênita é utilizado para designar uma série de distúrbios neutropênicos,de caráter permanente, intermitente, grave (< 500 neutrófilos/mm3 de sangue), ou moderado(entre 500-1.500 neutrófilos/mm3 de sangue), que podem acometer pele e mucosa do tratorespiratório e gastrintestinal. Quando a neutropenia é diagnosticada, ela deve ser distinguidadas formas adquiridas, incluindo a neutropenia pós-viral e a autoimune, da forma congênita,que pode ser uma enfermidade isolada ou fazer parte de uma doença genética. Cinquenta porcento das formas congênitas de neutropenia apresentam manifestação extra-hematopoiéticacom resposta imune adaptativa normal e infecções recorrentes no início da vida. O tratamentodestes pacientes tem por objetivo o controle e a prevenção de infecções através do uso profiláticode antibióticos, e outra forma de tratamento consiste na utilização de fator estimuladorde colônia de granulócitos recombinante humano (rHUG-CSF), que aumenta o número degranulócitos, diminui o número infecções e melhora de forma significativa a sobrevida e qualidadede vida. A revisão foi realizada por levantamento bibliográfico de banco de dados obtidosatravés de pesquisa direta, LILACS, MEDLINE e capítulos de livros. A revisão literária demonstraa importância dos neutrófilos pela defesa do hospedeiro contra micro-organismos, e defeitosgenéticos que envolvem estas células acarretam maior susceptibilidade a infecções microbianasem locais como pele e mucosa do trato respiratório e gastrintestinal. Estes defeitos genéticosdos neutrófilos envolvem o seu número, função, ou ambos. Como estes defeitos envolvendofagócitos são de caráter congênito e hereditário, as crianças são os pacientes predominantes. Osneutrófilos apresentam um papel importante na imunidade inata, prevenindo o surgimento deinfecções de repetição. O tratamento com rHUG-CSF aumenta o número de granulócitos, diminuio número de novas infecções e melhora de forma significativa a sobrevida e qualidade de vida.O transplante de células-tronco hematopoiéticas é indicado em casos refratários ao tratamentocom rHUG-CSF que apresentam infecções recorrentes graves e resistência ao tratamento semdetecção de mielodisplasia/leucemia.

Here we aim to review pathogenic mechanisms related to congenital neutropenia. The termcongenital neutropenia has been used to designate a series of neutropenic disorders that canbe permanent, intermittent, severe (< 500 neutrophils/mm3) or moderate (500-1500 neutrophils/mm3), which could affect the skin and mucosa of the respiratory and gastrointestinal tracts. Whenneutropenia is diagnosed, it is necessary to distinguish between the acquired form, includingpost-viral and autoimmune neutropenia, and the congenital form, a disease that can occur eitheralone or as part of a genetic disease. Fifty percent of the congenital forms of neutropenia haveextra-hematopoietic manifestations, with normal adaptive immune response and recurrent infections in early life. Treatment of these patients focuses primarily on controlling and preventing infections through the use of prophylactic antibiotics; another treatment approach is the use of recombinant human granulocyte colony-stimulating factor (rHUG-CSF), which increases the number of granulocytes, reduces the number of infections, and significantly improves survival rates and quality of life in these patients. Papers were directly searched on the LILACS and MEDLINE database Book chapters were also reviewed. The literature reviewed underscores theimportance of neutrophils for host defense against microorganisms and the association betweengenetic defects involving these cells and an increased susceptibility to microbial infections inthe skin and mucosa of the respiratory and gastrointestinal tracts. Genetic defects may affectneutrophil number, function, or both. Because defects involving phagocytes have a congenitaland hereditary origin, children are the most common patients. Neutrophils have an importantrole in innate immunity, preventing the emergence of recurrent infections. Treatment withrHUG-CSF increases the number of granulocytes, decreases the number of new infections, andsignificantly improves survival rates and quality of life. Hematopoietic stem cell transplantationis indicated in patients refractory to rHUG-CSF treatment with severe and recurrent infectionsand resistance to treatment with no detection of myelodysplasia/leukemia.

Profile of Patients With Von Gierke Disease From India.

Molecular diagnosis of Von Gierke disease is possible by mutation analysis of G6PC gene. GSD type 1a cases account for 20 % of glycogenoses in our center. We diagnosed ten unrelated patients with glycogen storage disease based on clinical, biochemical and histopathology investigations. Mutation analysis was done by sequencing the G6PC gene. Two unrelated patients were found to be homozygous for a novel mutation c.355 C>G (p.H119D). They were born to non-consanguineous parents from Karnataka. This suggests founder effect. Mutation detection confirms the diagnosis and assists in counseling and prenatal diagnosis.