Chi-Ren Tsai

Leigh Syndrome: Clinical and Neuroimaging Follow-Up

Leigh syndrome, caused by dysfunction in mitochondrial energy metabolism, is an inherited, heterogeneous, and progressive neurodegenerative disorder of infancy and childhood. From 1983 to August 2006, 14 cases diagnosed with Leigh syndrome were studied in terms of characteristic neuroimaging findings and abnormal mitochondrial configurations under electron microscopy, as well as molecular analysis. Of the 14 cases, 11 presented clinical features before age 1 (79%). All 14 presented with variable symptoms of central nervous system involvement. The three most common symptoms were developmental delay (12/14; 86%), seizures (11/14; 79%), and altered consciousness (8/14; 57%). Extra-central nervous system manifestations were observed in 10 of the 14 cases, the most common symptoms being failure to thrive (5/14; 36%), pericardial effusion and dilated cardiomyopathy (3/14; 21%), and liver function impairment (3/14; 21%). In all 14 cases, neuroimaging revealed abnormal findings over the basal ganglion, brainstem, or both. The putamen was the most common lesion site in the basal ganglia (11/12; 92%). Cranial magnetic resonance imaging was used for follow-up in 6 cases because of changes in clinical features; in all 6 cases the imaging revealed evolution in the brain. Cranial magnetic resonance spectroscopy was performed in 3 cases and in 2 of them revealed lactate peaks during deterioration of the disease course. The prognosis for Leigh syndrome was poor during long-term follow-up. Seven cases were early fatalities, before 1 year and 6 months of age. Follow-up cranial magnetic resonance imaging together with magnetic resonance spectroscopy in cases with clinical evolution is helpful for monitoring this disease.

Aromatic l-amino acid decarboxylase deficiency in Taiwan

BACKGROUND Aromatic L-amino acid decarboxylase (AADC) deficiency is a rare autosomal recessive disorder of neurotransmitter synthesis. It has unique clinical presentations. AIMS The purpose of this study is to delineate the clinical features and molecular spectrum of AADC deficiency in Taiwanese infants and children. METHODS We report eight patients with characteristic clinical manifestations of AADC deficiency. Clinical presentations, treatment response, outcome and mutations of DOPA decarboxylase (DDC) gene were analyzed. RESULTS The clinical manifestations were similar to those previously reported, including symptoms onset before age 1 year with features of severe floppiness, oculogyric crises, athetoid movement, prominent startle response, tongue thrusting, ptosis, paroxysmal diaphoresis, nasal congestion, diarrhea, irritability and sleep disorders. In addition, we observed that all patients (100.0%) had small hands and feet. During the period of follow-up, all of them (100.0%) presented severe floppiness in spite of therapeutic trials with vitamin B6, dopamine agonist, MAO inhibitor and/or anticholinergics. Three different mutations were identified in the DDC gene, including two novel mutations 1303 C>T and 1367ins A and one IVS 6+4 A>T mutation. The IVS 6+4 A>T was a splicing mutation, which inserted an additional 37nt of intron 6 into the DDC mRNA. Thirteen out of 16 alleles (81.3%) carried IVS 6+4 A>T mutation and the IVS 6+4 A>T alleles shared a conserved haplotype. CONCLUSIONS Patients with AADC deficiency in Taiwan have particular clinical manifestations of small hands and feet, which have rarely been mentioned in the literature. The prevalence of IVS 6+4 A>T splicing mutation is high in our study group and the IVS 6+4 A>T mutation might have a founder effect.

Lactate peak on brain MRS in children with syndromic mitochondrial diseases

Background: Brain magnetic resonance spectroscopy (MRS) has been reported to be a valuable noninvasive tool in the diagnosis of some rare diseases. In this study, our aim was to assess lactate peak on single‐voxel proton MRS in children with syndromic mitochondrial diseases (MDs). Methods: From March 2004 to November 2010, 14 patients who were diagnosed with syndromic MDs underwent single‐voxel proton MRS examination. The volume of interest was positioned on axial magnetic resonance imaging (MRI), and voxels were sampled using short (35 milliseconds), intermediate (144 milliseconds), or long (288 milliseconds) echo times for determination of lactate at 1.33 parts/million. Results: Twelve of fourteen patients (85.7%) exhibited lactate peaks on the initial single‐voxel proton MRS, and all of them showed abnormal MRI findings. The correlations of lactate level in blood and lactate peak on single‐voxel proton MRS were inconsistent. Among the 12 patients, eight (66.7%) had corresponding elevated levels of blood lactate, and four (33.3%) had normal levels of blood lactate. Compared with a positive rate of 85.7% for patients with lactate peaks on the single‐voxel proton MRS, the positive rates for diagnosing syndromic MDs by using electron microscopic examination of muscle biopsy, oral glucose lactate stimulation test, and blood lactate level were 100%, 91.7%, and 71.4%, respectively. Conclusion: Lactate acquisition on single‐voxel proton MRS provides a noninvasive and complementary tool for the diagnosis of syndromic MDs, especially in children with abnormal signal changes on the brain MRI or a normal blood lactate level.

Epileptic Seizures in Infants and Children With Mitochondrial Diseases

The purpose of this study is to describe the characteristics of epileptic seizures in infants and children with mitochondrial diseases. From 1984 to December 2010, data from 46 of 76 patients diagnosed as having mitochondrial diseases with epileptic seizures were reviewed. Age at seizure onset, epileptic phenotypes, electroencephalogram findings, magnetic resonance imaging features, and treatment outcome in patients with syndromic or nonsyndromic mitochondrial diseases were analyzed. Thirty (65%) of 46 patients manifested seizures before the age of 1 year; 43% had Leigh syndrome and 53% had nonsyndromic mitochondrial diseases. Twenty-eight (61%) of 46 patients exhibited seizures as the manifesting complaint. Nineteen (68%) of 28 patients had nonsyndromic mitochondrial diseases. The most frequently observed electroencephalogram finding was background slow activity (28/46; 61%) in both groups. The most common cortical abnormality relevant to clinical seizures was diffuse brain atrophy on the brain magnetic resonance imaging (26/45; 58%), which was commonly observed in patients with nonsyndromic mitochondrial diseases (16/26; 62%). Despite treatment, 49% of patients experienced less than 50% seizure reduction rate, 77% of whom had nonsyndromic mitochondrial diseases. Leigh syndrome and nonsyndromic mitochondrial diseases often manifest as infantile seizures. Epileptic seizure as the initial complaint, diffuse brain atrophy, and refractory epilepsy were more common in patients with nonsyndromic mitochondrial diseases.

Tyrosine Hydroxylase Deficiency in Taiwanese Infants

We analyzed the clinical manifestations, genetic mutations, treatment responses to L-dopa, and long-term neurologic outcomes in Taiwanese infants with tyrosine hydroxylase deficiency. From 1999 to May 2011, we enrolled six infants who had been diagnosed with tyrosine hydroxylase deficiency by identifying point mutations on the tyrosine hydroxylase gene. Two patients manifested fetal distress during the perinatal period. Four patients exhibited generalized tremor as their first observed neurologic sign at age 3 months. All presented brisk reflexes, hypokinesia, rigidity, distal chorea, and athetosis. We identified a novel missense mutation, I382T, and report on the first patient, to the best of our knowledge, with a homozygous R153X nonsense mutation. Five of six patients responded to L-dopa at a dose of 4.2-34.7 mg/kg/day combined with biperiden or selegiline or both. Long-term neurologic outcomes (median follow-up, 5 years and 10.5 months) revealed two patients demonstrated slightly low intelligence quotients, three demonstrated mild to moderate psychomotor retardation, and one died of respiratory failure. A higher dose of L-dopa, together with alternative therapies, may lead to improvements in motor function. However, several years of observation may be needed to reach definitive conclusions about neurologic outcomes.

Clinical manifestations in children with mitochondrial diseases.

Mitochondrial diseases comprise a group of complex and heterogeneous genetic disorders. Variable clinical features present a major challenge in pediatric diagnoses. From January 1984-June 2009, 69 patients were diagnosed with either syndromic mitochondrial diseases or nonsyndromic mitochondrial diseases. Clinical manifestations, laboratory findings, and histopathologic results differentiating syndromic from nonsyndromic mitochondrial diseases were analyzed by chi(2) test, with cutoff significance at P = 0.05. The commonest clinical manifestation involved central nervous system signs (88.4%). A comparison of central nervous system signs in syndromic vs nonsyndromic mitochondrial diseases revealed significant differences in terms of headache, external ocular motility, and apnea (P < 0.05). A comparison of organ systems revealed a significant difference for signs of the cardiovascular system. Elevated initial blood lactate levels were evident in 40.6% of patients, and 84.8% produced abnormal results after oral glucose challenge. Ragged red fibers were observed in 51.6% of patients. The positive rate of mitochondrial gene mutation was 27.5%. Age and disease were directly related: the younger the age at initial disease onset, the higher the frequency of mortality and morbidity. Notorious variability in the presentation of mitochondrial diseases exists in all pediatric subspecialties. Greater familiarity with those signs will facilitate more accurate diagnoses.

Electroencephalographic features of patients with SCN1A-positive Dravet syndrome

OBJECTIVE The aim of this study was to characterize the awake EEG features of patients with SCN1A-positive Dravet syndrome. METHODS Between January 2002 and December 2012, clinical data of 37 SCN1A-positive Dravet syndrome patients were collected. The first interictal awake EEG features, hot water bath test induced ictal seizure patterns and the concomitant EEG results, as well as follow-up interictal awake EEG recordings were analyzed. RESULTS Thirty-seven interictal awake EEG recordings showed 43.2% had normal features, 43.2% had nonspecific findings, and 13.5% had abnormal epileptiform discharges. Ictal pleomorphic seizure types with a median number of three were recorded in 26 patients. In total, 42.3% exhibited myoclonic seizures as their first recognizable seizure type with simultaneous EEG findings characterized by generalized or focal spikes, generalized 2-3.5Hz spike and wave discharges, or generalized 2-3Hz high voltage slow waves, and 30.8% manifested atypical absence seizures with concomitant EEG results showing generalized or focal spikes. Fifteen patients had 45 follow-up interictal awake EEGs during a period of six years. The follow-up awake EEG recordings revealed 42.2% had normal features, 42.2% showed nonspecific findings, and 15.6% disclosed epileptiform discharges. CONCLUSIONS The initial and follow-up interictal awake EEG recordings showed normal results and nonspecific features in the majority of SCN1A-positive Dravet syndrome patients. Ictal electroencephalographic seizure types and concomitant EEG pictures were quite diverse and polymorphous. A low detection rate of interictal epileptiform abnormalities at awake stage might make patient management more challenging.

Cranial Magnetic Resonance Imaging Findings in Children With Nonsyndromic Mitochondrial Diseases

Cranial magnetic resonance imaging findings suggestive of specific mitochondrial syndromes are reported. However, cranial magnetic resonance imaging features in children with nonsyndromic mitochondrial diseases are rarely described. From January 1992-September 2009, data from 33 patients with nonsyndromic mitochondrial diseases were collected. We investigated cranial magnetic resonance imaging features in children with nonsyndromic mitochondrial diseases, and identified potential diagnostic characteristics. Eleven of 33 patients (33.3%) demonstrated normal findings, and 22 (66.7%) demonstrated abnormal findings. The most common abnormal finding was cerebral atrophy, with or without other lesion sites (15/33; 45.5%). The second most common was bilateral basal ganglia involvement (6/33; 18.2%). Follow-up imaging was performed in 20 patients. Ten of these 20 (50.0%) demonstrated evolutionary changes, in which progressive global brain atrophy was evident. Three patients with normal results and one patient with cerebral atrophy on initial imaging demonstrated prominent signal changes over the basal ganglia, brainstem, gray matter, white matter, and bilateral cerebellar hemispheres on follow-up imaging. Imaging in children with nonsyndromic mitochondrial diseases may produce variable findings. Normal results and cerebral atrophy on the initial cranial magnetic resonance imaging are commonly evident in this patient group.

Early cardiac involvement in an infantile Sandhoff disease case with novel mutations

INTRODUCTION Hepatosplenomegaly is often present in infantile Sanshoff disease. However, cardiac involvement is extremely uncommon. CASE REPORT We describe a 14-month-old female baby who exhibited mitral regurgitation and cardiomegaly at the age of 2months, dilation of the left atrium and left ventricle at age of 6months, followed by regression of developmental milestones after an episode of minor infection at age of 14months. Brain magnetic resonance imaging revealed signal changes over the bilateral thalami, bilateral cerebral white matter and left putamen. An examination of the fundus showed presence of cherry-red spots in both macular areas. The lysosomal enzymatic activities showed a marked reduction of β-hexosaminidase B (HEXB) activity. Two novel mutations of HEXB gene were identified. One of the mutations was a c.1538 T>C mutation, which predicted a p.L513P amino acid substitution of leucine to proline; the other was a c.299+5 G>A mutation, which was a splice site mutation. CONCLUSION Cardiac involvement might occur prior to neurological symptoms in infantile Sandhoff disease, and it should be included in the differential diagnoses of metabolic cardiomyopathies in the infantile stage.

Antisense oligonucleotides modulate dopa decarboxylase function in aromatic l-amino acid decarboxylase deficiency

Aromatic l‐amino acid decarboxylase deficiency (AADCD), attributed to mutations in the dopa decarboxylase (DDC) gene, is a rare neurometabolic disease resulting from a defect in the biosynthesis of dopamine and serotonin. The DDC c.714+4A>T mutation is the most prevalent mutation among patients with AADCD, and is also a founder mutation among Taiwanese patients. In this study, the molecular consequences and function of this mutation were examined in AADCD patient‐derived lymphoblastoid cells. We identified novel DDC mRNA isoforms spliced with a new exon (exon 6a) in normal and c.714+4A>T lymphoblastoid cells. In addition, we identified the SR proteins (SRSF9 and SRSF6), as well as cis‐elements involved in modulating the splicing of this mutated transcript. Notably, we demonstrated that antisense oligonucleotides (ASOs) were able to restore the normal mRNA splicing and increase the level of DDC protein, as well as its downstream product serotonin, in lymphoblastoid cells derived from the patient with AADCD, suggesting that these ASOs might represent a feasible alternative strategy for gene therapy of AADCD in patients with the common c.714+4A>T mutation.