Clinical and genetic features of 12 families with Pompe disease / 中华神经医学杂志

Objective:To investigate the clinical and genetic features of Pompe disease, and analyze the effect of enzyme replacement therapy on it.Methods:A retrospective study was performed. The clinical data and genetic results of 14 patients with Pompe disease from 12 families, admitted to our hospital from January 2017 to June 2021, were collected. Some patients were followed up after therapies.Results:Twelve of the 14 patients were late onset, with onset age ranged from 1.5 to 37.0 years (mean 15.2 years), and the other 2 patients were infantile onset. The predominant manifestations included proximal lower limb weakness, accompanied by easy fatigue and myalgia; 8 patients presented with dyspnea, of which one had dyspnea as initial presentation. Serum creatine kinase ranged from 172 to 1397 IU/L (mean 878 IU/L). Electromyography revealed myogenic pattern in 6 patients and myotonic discharge in 4 patients. Forced vital capacity decreased in 10 patients, and scoliosis was detected in 5 patients; 13 patients had decreased acid-alpha-glucosidase (GAA) activity; muscle pathology indicated vacuolar myopathy in 8 patients. Genetic test revealed 17 variants in GAA gene, among which c.2331G>C, c.1622C>T, c.1585T>C, and c.1837T>C were 4 novel likely pathogenic variants. The c.2238G>C and c.2662G>T were found in 5 and 3 families, respectively. Muscle strength and lung function got improvement in 1 patient who received enzyme replacement therapy and had regular follow-up, while muscle strength and lung function were worsened in those who did not receive enzyme replacement therapy. Conclusions:Pompe disease is characterized by skeletal muscle weakness and pulmonary dysfunction, and may be associated with spinal deformity; creatine kinase is mildly to moderately elevated, and myotonic discharge can be detected. GAA c.2238G>C and c.2662G>T are hotspot mutations in China; the 4 novel variants enrich the GAA mutational spectrum. Enzyme replacement therapy may improve motor and pulmonary function.

A novel nonsense mutation p.W738X of GAA gene identified in a Chinese patient with infantile glycogen storage disease type Ⅱ / 临床儿科杂志

Objective To investigate the acid α glucosidase(GAA)gene mutations and clinical features of a Chinese patient exhibiting signs and symptoms of infantile glycogen storage disease type Ⅱ(GSD Ⅱ). Methods Clinical features of the patient were reviewed,and GAA activity in the patient＇s and her parents＇ whole leukocytes were measured. GAA coding regions were amplified by polymerase chain reaction(PCR),and analyzed by direct DNA sequencing. Results The patient showed feeding difficulties,generalized hypotonia and weakness starting at 2 months of age. Cardiomegaly and cardiomyopathy were found at 4 months. She died of cardiorespiratory failure at the age of 6 months. GAA activity in leukocytes was low in the patient(17.3% of the median normal range). Genotyping revealed the patient was a heterozygote for a novel nonsense mutation p.W738X and a previously reported nonsense mutation p.E888X. The reported pseudodeficiency allele c.1726G ＞ A;2065G ＞ Awas found in the patient and her mother. Conclusions Correct diagnosis was made for this patient by combination of GAA activity assay and genetic analysis. From the clinical course,this patient should be classified as infantile type of GSD Ⅱ,suggesting that the novel mutation p.W738X may have a damaging effect on the function of GAA. Pseudodeficiency allele found in this family highlights the importance of genetic analysis of GAA when performing diagnosis and prenatal diagnosis for the affected families,as this allele causes low GAA activity in normal individuals.