Congenital myasthenic syndrome 22 due to PREPL gene mutation in 2 patients: case report and literature review / 中华实用儿科临床杂志

Clinical data of two patients with congenital myasthenia syndrome type 22 (CMS22) treated at the Children′s Hospital of Fudan University from February 2019 to November 2021 were retrospectively analyzed, and relevant literatures were reviewed.Both patients were female, aged 3 months 18 days and 3 months 26 days, respectively, with typical clinical features of CMS (postnatal onset, skeletal muscle weakness, feeding difficulties, and delayed motor development). Genetic testing revealed that one patient had a homozygous frameshift mutation of the PREPL gene from maternal uniparental disomy c. 1282_1285del(p.F428fs*18), and the other one had a compound heterozygous mutation, including the paternal homozygous frameshift mutation of the PREPL gene and maternal monoallelic nonsense mutation and splicing mutation c. [1501G>T; 2020+ 1G>T], p.[G501*; -]. Two patients were treated with Pyridostigmine bromide at the age of 6 months old and 4 months old, respectively, and the medication last for 15 months and 3 months (still under treatment), respectively.The treatment was effective.Through literature review, 7 English language articles were retrieved, involving 13 cases (2 cases in the presented study were included). The main clinical symptoms of CMS22 included neonatal onset with feeding difficulties and motor development delay, accompanied by cognitive impairment, growth hormone deficiency, and obesity.Genetic testing is favorable to the early diagnosis, early treatment, and symptom relief.

Congenital Myasthenic Syndrome / 罕见病研究

Congenital Myasthenic syndrome (CMS) is a group of partially treatable genetic disorders characterized by dysfunction of neuromuscular junction signaling.With the popularization of high-throughput sequencing and in-depth understanding of the disease in recent years, more than thirty pathogenic genes have been discovered and there is a correlation between genotype and clinical phenotype.Misdiagnosis and missed diagnosis are common in clinical practice. This paper summarized the molecular mechanisms, clinical features, electrophysiologic, pathological features and treatment of main subtypes of CMS to deepen the understanding of the disease.

Prevalence of mutations responsible for glycogen storage disease type-II and congenital myasthenic syndrome in Brazilian Brahman cattle / Prevalência de mutações responsáveis pela estocagem de glicogênio tipo II e síndrome miastênica congênita em bovinos brasileiros da raça Brahman

Glycogen storage disease type II (GSD-II) and congenital myasthenic syndrome (CMS) are important autosomal recessive disorders in Brahman cattle. The objective of this study was to investigate the presence of mutations responsible for GSD II (E7, c.1057_1058delTA; and E13, c.1783C>T) and CMS (c.470del20) in purebred Brazilian Brahman cattle and in purebred Brahman bulls that were routinely used in breeding programs in Brazil. A total of 276 purebred Brahman cattle (167 females and 109 males, with ages ranging from 12-24 months) and 35 frozen semen samples taken from purebred Brahman bulls (22 bulls from the USA, 11 Brazilian bulls, one Argentine bull and one Australian bull) were used in this study. Genomic DNA was purified from hair root samples and from semen samples. Purified DNA was used in PCR genotyping to mutations c.1057_1058delTA (E7) and c.1783C>T (E13) in the GAA gene and c.470del20 in the CHRNE gene. The PCR products were purified and sequenced. The genotypic frequencies per polymorphism were estimated separately. Of the 276 Brahman cattle tested, 7.3% were identified as heterozygous for E7. All Brahman cattle studied were homozygous for the wild-type E13 allele. The E7 mutations was identified as heterozygous in 8.6% (3/35) of the commercial semen samples, whereas the E13 mutations was not identified. The c.470del20 mutation was identified as heterozygous in 0.73% of the hair root samples, but this mutation was not present in any semen sample assessed. No study had previously evaluated the prevalence of mutations responsible for GSD II or CMS in Brazilian Brahman cattle. In summary, the E7 and c.470del20 mutations are present in the Brazilian Brahman herd, and control measures should be adopted to prevent an increase in the incidence of GSD-II and CMS in Brahman cattle in Brazil.(AU)

A doença de armazenamento de glicogênio tipo II (DAG-II) e a síndrome miastênica congênita (SMC) são importantes doenças autossômicas recessivas no gado Brahman. O objetivo deste estudo foi investigar a presença das mutações responsáveis pela DAG-II (E7, c.1057_1058delTA; e E13, c.1783C>T) e pela SMC (c.470del20) em bovinos da raça Brahman e em touros Brahman que são rotineiramente utilizados em programas de reprodução no Brasil. Um total de 276 amostras de bulbo piloso de bovinos Brahman (167 fêmeas e 109 machos, com idade variando de 12 a 24 meses) e 35 amostras de sêmen congeladas de touros Brahman (22 touros americanos, 11 touros brasileiros, um touro argentino e um touro australiano) foram usados neste estudo. O DNA genômico foi purificado, das amostras de bulbo piloso e de sêmen, e utilizado na genotipagem por PCR das mutações c.1057_1058delTA (E7) e c.1783C>T (E13) no gene GAA e c.470del20 no gene CHRNE. Os produtos de PCR foram purificados e sequenciados. A frequência genotípica para cada polimorfismo foi estimada separadamente. Dos 276 Brahman testados, 7,3% foram identificados como heterozigotos para E7. Todos os Brahman foram homozigotos wild-type para o alelo E13. A mutação E7 foi identificada em homozigose em 8,6% (3/35) das amostras de sêmen comerciais, enquanto que a mutação E13 não foi identificada. A mutação c.470del20 foi identificada em heterozigose em 0,73% das amostras de bulbo piloso, mas esta mutação não estava presente nas amostras de sêmen avaliadas. Nenhum estudo prévio avaliou a prevalência das mutações responsáveis pela DAG-II ou SMC em bovinos Brahman brasileiro. Em suma, as mutações E7 e c.470del20 estão presentes no rebanho Brahman brasileiro, e medidas de controle devem ser adotadas para prevenir o aumento da incidência da DAG-II e SMC em bovinos da raça Brahman no Brasil.(AU)

Limb Girdle Weakness Responding to Salbutamol: An Indian Family with DOK7 Mutation.

Background: Congenital Myasthenic Syndromes (CMS) are heterogeneous genetic diseases. Case characteristics: Two siblings presented with progressive limb girdle weakness without significant fluctuations or ocular muscle weakness. Repetitive nerve stimulation showed a decremental response and there was no response to pyridostigmine therapy. Outcome: A trial of salbutamol produced a remarkable, consistent improvement. Mutation in exon 5 of the DOK7 gene was found in both siblings. Message: Patients with congenital myasthenic syndrome with DOK 7 mutation benefit remarkably with salbutamol.