Variety of large rearrangements in the CFTR gene in Russian patients with Cystic Fibrosis

Целью исследования стал анализ частоты протяженных перестроек гена CFTR и клинико-лабораторных характеристик пациентов с протяженными перестройками гена CFTR. В Регистр больных муковисцидозом РФ 2017 г. включены данные 3096 пациентов из 81 региона РФ, у которых выявлено 196 патогенных вариантов гена CFTR. Патогенные варианты обнаруживаются как в кодирующих, так и в интронных областях, и в регуляторных регионах гена CFTR. В гене CFTR относительно мало (около 2,5%) протяженных перестроек, но среди мутантных хромосом, в которых генетические варианты не были идентифицированы стандартными методами, такие перестройки составляют до 20%. По данным Регистра 2017 г. выявлен 21 пациент, несущий в своем генотипе крупные перестройки. Перестройки CFTRdele12,13del16, CFTRdele19-22(17а-19), CFTRdele8(7*), CFTRdele2-8(2-7*) ранее не были описаны в международных базах данных. Клиническая характеристика больных с протяженными перестройками не отличалась по основным признакам от пациентов с «тяжелыми» генотипами. Наличие в генотипе пациентов с протяженными перестройками варианта нуклеотидной последовательности гена CFTR, определяющего сохранную функцию поджелудочной железы, обусловило отсутствие у них панкреатической недостаточности. The aim of the study was to analyze large rearrangements in the CFTR gene in patients with cystic fibrosis in the Russian Federation in 2017. The Cystic Fibrosis Patients Registry of the Russian Federation for 2017 includes data from 3096 patients from 81 regions of the Russian Federation. To date, more than 2,000 mutations or variants of the nucleotide sequence of the CFTR gene have been described. In the Cystic Fibrosis Patients Registry of the Russian Federation for 2017, 196 pathogenic CFTR variants are given. Pathogenic variants are found both in the coding and in the intron regions, and in the regulatory regions of the CFTR gene. The CFTR gene has relatively few (about 2.5%) large rearrangements, but among mutant chromosomes in which genetic variants were not identified by standard methods, such rearrangements account for up to 20%. According to the Registry of 2017, 21 patients were identified that carried large rearrangements in their genotype. The rearrangements CFTRdele12,13del16, CFTRdele19-22 (17a-19), CFTRdele8 (7*), CFTRdele2-8 (2-7*) are not described in international databases. The clinical characteristics of patients with extensive rearrangements in the genotype did not differ in basic characteristics from patients with “severe” genotypes. The presence of a genetic variant in the genotype that determines the preserved function of the pancreas leads to the preservation of gland function in patients with large rearrangements in the genotype.

Download Full-text

Clinical and genetic features of cystic fibrosis patients with novel pathogenic variant CFTR c.1083G> A (p.Trp361*) and functional assessment of the activity of the chloride channel

Nauchno-prakticheskii zhurnal «Medicinskaia genetika» ◽

10.25557/2073-7998.2019.09.9-18 ◽

2019 ◽

pp. 9-18

Author(s):

Е.И. Кондратьева ◽

Ю.Л. Мельяновская ◽

А.С. Ефремова ◽

Н.В. Булатенко ◽

Т.Б. Бухарова ◽

...

Keyword(s):

Cystic Fibrosis ◽

Russian Federation ◽

Genetic Variant ◽

Clinical Manifestations ◽

Pathogenic Variant ◽

Cftr Gene ◽

Genetic Characteristics ◽

Intestinal Organoids ◽

The Russian Federation ◽

First Time

В статье впервые представляется клинико-генетическая характеристика мутации c.1083G>A (p.Trp361*) в гене CFTR. Патогенный генетический вариант c.1083G>A (p.Trp361*) гена CFTR относится к нонсенс-мутациям (I класс) и впервые был внесён в базу данных CFTR1 (http://www.genet.sickkids.on.ca) в середине 2019 г. без описания клинической картины муковисцидоза. Методы. Проведен анализ амбулаторных карт и историй болезни двух пациентов из неродственных семей с редким генетическим вариантом c.1083G>A (p.Trp361*). Для определения разности кишечных потенциалов (ОРКП) и проведения форсколинового теста на кишечных органоидах использовали биопсийный материал слизистой прямой кишки пациентов. ДНК для секвенирования выделяли из лейкоцитов венозной крови пациентов. Результаты. Анализ клинических проявлений заболевания у детей 6 и 9 лет показал наличие хронической панкреатической недостаточности, более выраженной у одного ребенка с синдромом дистальной интестинальной обструкции кишечника в анамнезе. Клиническая картина второго пациента характеризовалась развитием в раннем возрасте транзиторной гипербилирубинемии, синдрома псевдо-Барттера, а в дальнейшем - повторными эпизодами бронхиальной обструкции и развитием полипозного риносинусита. ОРКП и форсколиновый тест на кишечных органоидах показали, что генетический вариант c.1083G>A (p.Trp361*) относится к вариантам гена CFTR с отсутствием функции хлорного канала. Выводы. Впервые представлены описание клинической картины муковисцидоза у двух пациентов из неродственных семей с патогенным вариантом c.1083G>A (p.Trp361*) в компаунде с вариантом c.1521_1523delCTT (p.Phe508del) (ранее называемом F508del) и результаты оценки функции белка CFTR методом ОРКП и форсколиновым тестом на кишечных органоидах. In this article we continue to describe the pathogenic variants of the CFTR gene identified among Russian cystic fibrosis (CF) patients. For the first time the clinical and genetic characteristics of the mutation c.1083G> A (p.Trp361 *) are presented. The pathogenic genetic variant c.1083G> A (p.Trp361 *) of the CFTR gene belongs to the nonsense mutations (class I) and was listed for the first time in the CFTR1 database (http://www.genet.sickkids.on.ca) by Professor Milan Macek et al. in mid-2019 without any description of clinical manifestations of cystic fibrosis. Methods. The data of the National Register of Patients with Cystic Fibrosis of the Russian Federation 2017 were analyzed. Outpatient records and case histories of two patients from unrelated families carrying a rare genetic variant c.1083G> A (p.Trp361 *) were analyzed. To determine the Intestinal current measurement (ICM) and Forskolin-induced swelling (FIS) in intestinal organoids, rectal biopsy material of CF patients was used. DNA for sequencing was isolated from leukocytes of venous blood of the patients. Results. Variant c.1083G> A (p.Trp361 *) was found in two patients from unrelated families from different regions of the Russian Federation, according to the Register of Cystic Fibrosis Patients in the Russian Federation 2017. Analysis of clinical manifestations of the disease in children 6 and 9 years old showed the presence of chronic pancreatic insufficiency, more expressed in one child with a history of distal intestinal obstruction syndrome. The clinical manifestation of the second patient was characterized by the development of transient hyperbilirubinemia, Pseudo-Bartter’s syndrome at an early age, and subsequently repeated episodes of bronchial obstruction and the development of polypoid rhinosinusitis. The ICM method and the FIS in intestinal organoids showed that the genetic variant c.1083G> A (p.Trp361 *) refers to the variants of the CFTR gene with the absence of chlorine channel function. Conclusion. The clinical picture of cystic fibrosis in two patients from unrelated families with the pathogenic variant c.1083G> A (p.Trp361 *) in the compound with variant c.1521_1523delCTT (p.Phe508del) (variant legacy name F508del) and results of the evaluation of the CFTR protein functions, obtained by the method of ICM and using the FIS assay in intestinal organoids, are presented for the first time. Patients continue to be under the control in Russian CF centers.

Download Full-text

Clinical and genetic characteristics of rare pathogenic variants of the CFTR gene in Russian patients with cystic fibrosis

Russian Pulmonology ◽

10.18093/0869-0189-2021-31-2-148-158 ◽

2021 ◽

Vol 31 (2) ◽

pp. 148-158

Author(s):

A. Yu. Voronkova ◽

Yu. L. Melyanovskaya ◽

N. V. Petrova ◽

T. A. Adyan ◽

E. K. Zhekaite ◽

...

Keyword(s):

Cystic Fibrosis ◽

Genetic Variants ◽

Pancreatic Insufficiency ◽

Protein Energy Malnutrition ◽

Molecular Genetic ◽

Clinical Manifestations ◽

Cftr Gene ◽

Genetic Characteristics ◽

Missense Variants ◽

Pathogenic Variants

The variety of clinical manifestations of cystic fibrosis is driven by the diversity of the CFTR gene nucleotide sequence. Descriptions of the clinical manifestations in patients with the newly identified genetic variants are of particular interest.The aim of this study was to describe clinical manifestations of the disease with the newly identified genetic variants.Methods. Data from Registry of patients with cystic fibrosis in the Russian Federation (2018) were used. The data review included three steps — the search for frequent mutations, Sanger sequencing, and the search for extensive rearrangements by MLPA. 38 pathogenic variants were identified that were not previously described in the international CFTR2 database. We selected and analyzed full case histories of 15 patients with 10 of those 38 pathogenic variants: p.Tyr84*, G1047S, 3321delG, c.583delC, CFTRdele13,14del18, CFTRdele19-22, c.2619+1G>A, c.743+2T>A, p.Glu1433Gly, and CFTRdel4-8del10-11.Results. A nonsense variant p.Tyr84* was found in 5 patients (0.08 %). Two missense variants c.3139G>A were found in 2 siblings (0.03 %). The c.4298A>G was found in 1 patient. Other variants were detected in a single patient (0.02 %) each. They included two variants of a deletion with a shift of the reading frame 3321delG and c.583delC, two splicing disorders c.2619+1G>A and c.743+2T>A, three extended rearrangements CFTRdele19-22, CFTRdele13,14del18, and CFTRdel4-8del10-11. The last two variants include 2 rearrangements on one allele, which cause the severe course in two young children. 8 of the 10 variants are accompanied by pancreatic insufficiency (PI). Among patients with p.Tyr84*, one had ABPA, one had liver transplantation, and all had Pseudomonas aeruginosa infection. Nasal polyps were diagnosed in 2 patients with p.Tyr84*, 1 with G1047S, 1 with CFTRdel4-8del10-11, and 1 patient with 3321delG, who also had osteoporosis and cystic fibrosis-related diabetes (CFRD). 2 patients with PI with 3321delG and CFTRdel4-8del10-11 genetic variants, and 1 with PI with p.Glu1433Gly genetic variant had severe protein-energy malnutrition (PEM).Conclusion. Clinical manifestations of previously undescribed CFTR genetic variants were described. 5/10 genetic variants should be attributed to class I, 3/10 – to class 7 of the function classification of pathogenic CFTR gene variants associated with transcription and translation disruptions. Class of the identified missense variants c.3139G>A and c.4298A>G has not been established and requires further functional, cultural, and molecular genetic studies.

Download Full-text