Clinical and genetic characteristics of children with Leigh syndrome

Abstract

Objective: To investigate the clinically and genetic characteristics of children with Leigh syndrome. Method: Patients with clinically diagnosed Leigh syndrome(LS)in the department of Neurology, Beijing Children's Hospital from January 2013 to February 2016 underwent the mitochondrial DNA (mtDNA) and nuclear DNA (nDNA) detecting with next generation sequencing (NGS) technology. The clinical data of gene confirmed cases were retrospectively collected and analyzed. The differences in the onset age, clinical manifestations, lactic acid level and MRI results between the mtDNA variation and nDNA variation were compared and analyzed.t test, Chi-square test and Fisher's exact test were used for statistical analysis. Result: Thirty-five cases were diagnosed by gene detection, including 20 males and 15 females. The median onset age was 1 year (ranging from the neonatal period to 4.4 years old). The age of onset within 2 years accounted for 74%(26 cases). The onset age of initial symptoms, including developmental delay, developmental regression, and seizures, were 6 (4, 12) months, 12 (8, 14) months, and 6 (1, 23) months respectively. The onset age of ptosis, extrapyramidal symptoms and ataxia were 26 (18, 44) months, 28 (23, 40) months and 28 (19, 35) months, respectively. There were significant differences in the onset age between the three groups (H=21.919, P=0.01). Within the 35 cases, 29 were manifested with developmental delay (83%), 26 with dystonia (74%), 18 with growth retardation, 15 with myasthenia, 13 with developmental regression, 11 with dysphagia, 10 with feeding difficulties, 4 with skeletal dysplasia, and 2 with digestive tract symptoms; nystagmus and respiratory abnormalities were observed in 9 cases respectively; extrapyramidal symptoms, peripheral nerve injury, ptosis, seizures were observed in 8 cases respectively; and ataxia, ophthalmoplegia and hypertrichiasis were found in 5 cases respectively.The blood lactic acid was measured in 32 LS patients, within which 23 cases (72%) had increased results; 8 out of 11 cases who underwent were cerebrospinal fluid lactic acid test had increased results. The results of neuroimaging revealed that all the patients were involved in the brainstem and (or) basal ganglia, of whom 27 (77%) had brainstem involvement, 24 (69%) had basal ganglia involvement. Thirteen out of 14 patients who had medulla oblongata involvement had nDNA variation; while 7 out of 8 patients with cerebellar involvement had nDNA variation. Genetic etiology was confirmed in all patients, among whom there were 17 cases (49%) with mtDNA mutation, including 8993T>C/G (n=5), 14487T>C (n=4), 13513G>A (n=2), 9176T>C, 10158T>C, 3697G>A, 10191T>C, 14459A>G and 11777C>A (n=1) respectively. Remaining 18 cases(51%) had nDNA mutation, including SURF1 gene(n=10), PDHA1 gene(n=3) and one case each of NDUFV1, NDUFAF6, NDUFAF5, NDUFS1 and COQ7 genes. In this study, 27 types of mutations were founded, 15 of which had not been previously reported. Respiratory chain gene mutations have been found in 31 cases(89%); 3 cases had PDHc gene mutations, and 1 case had other mutation. Conclusion: LS usually occurs in infants. The most common primary symptoms are age-dependent abnormal movements, ocular symptoms, and seizures. Respiratory chain defects is the most common causes of LS.SURF1 is the most common variation, followed by 8993T>C/G, 14487 T>C and 13513G>A mutation.