Using the C14:1/Medium-Chain Acylcarnitine Ratio Instead of C14:1 to Reduce False-Positive Results for Very-Long-Chain Acyl-CoA Dehydrogenase Deficiency in Newborn Screening in Japan

Very-long-chain acyl-CoA dehydrogenase (VLCAD) deficiency is a long-chain fatty acid oxidation disorder that manifests as either a severe phenotype associated with cardiomyopathy, a hypoglycemic phenotype, or a myopathic phenotype. As the hypoglycemic phenotype can cause sudden infant death, VLCAD deficiency is included in newborn screening (NBS) panels in many countries. The tetradecenoylcarnitine (C14:1) level in dried blood specimens is commonly used as a primary marker for VLCAD deficiency in NBS panels. Its ratio to acetylcarnitine (C2) and various other acylcarnitines is used as secondary markers. In Japan, tandem mass spectrometry-based NBS, initially launched as a pilot study in 1997, was introduced to the nationwide NBS program in 2013. In the present study, we evaluated levels of acylcarnitine with various chain lengths (C18 to C2), free carnitine, and their ratios in 175 infants who tested positive for VLCAD deficiency with C14:1 and C14:1/C2 ratios. Our analyses indicated that the ratios of C14:1 to medium-chain acylcarnitines (C10, C8, and C6) were the most effective markers in reducing false-positive rates. Their use with appropriate cutoffs is expected to improve NBS performance for VLCAD deficiency.

Newborn Screening with (C16 + C18:1)/C2 and C14/C3 for Carnitine Palmitoyltransferase II Deficiency throughout Japan Has Revealed C12/C0 as an Index of Higher Sensitivity and Specificity

Carnitine palmitoyltransferase (CPT) II deficiency is a long-chain fatty acid oxidation disorder. It manifests as (1) a lethal neonatal form, (2) a hypoglycemic form, or (3) a myopathic form. The second form can cause sudden infant death and is more common among Japanese people than in other ethnic groups. Our study group had earlier used (C16 + C18:1)/C2 to conduct a pilot newborn screening (NBS) study, and found that the use of C14/C3 for screening yielded lower rates of false positivity; in 2018, as a result, nationwide NBS for CPT II deficiency started. In this study, we evaluated the utility of these ratios in 71 NBS-positive infants and found that the levels of both C14/C3 and (C16 + C18:1)/C2 in patients overlapped greatly with those of infants without the disease. Among the levels of acylcarnitines with various chain lengths (C18 to C2) and levels of free carnitine (C0) as well as their ratios of various patterns, C12/C0 appeared to be a promising index that could reduce false-positive results without missing true-positive cases detected by current indices. Although some cases of the myopathic form may go undetected even with C12/C0, its use will help prevent life-threatening onset of the hypoglycemic form of CPT II deficiency.

Low carnitine palmitoyltransferase 1 activity is a risk factor for narcolepsy type 1 and other hypersomnia

Study Objectives

Narcolepsy type 1 (NT1) is associated with metabolic abnormalities but their etiology remains largely unknown. The gene for carnitine palmitoyltransferase 1B (CPT1B) and abnormally low serum acylcarnitine levels have been linked to NT1. To elucidate the details of altered fatty acid metabolism, we determined levels of individual acylcarnitines and evaluated CPT1 activity in patients with NT1 and other hypersomnia.

Methods

Blood samples from 57 NT1, 51 other hypersomnia patients, and 61 healthy controls were analyzed. The levels of 25 major individual acylcarnitines were determined and the C0/(t[C16] + t[C18]) ratio was used as a CPT1 activity marker. We further performed transcriptome analysis using independent blood samples from 42 NT1 and 42 healthy controls to study the relevance of fatty acid metabolism. NT1-specific changes in CPT1 activity and in expression of related genes were investigated.

Results

CPT1 activity was lower in patients with NT1 (p = 0.00064) and other hypersomnia (p = 0.0014) than in controls. Regression analysis revealed that CPT1 activity was an independent risk factor for NT1 (OR: 1.68; p = 0.0031) and for other hypersomnia (OR: 1.64; p = 0.0042). There was a significant interaction between obesity (BMI <25, ≥25) and the SNP rs5770917 status such that nonobese NT1 patients without risk allele had better CPT1 activity (p = 0.0089). The expression levels of carnitine-acylcarnitine translocase (CACT) and CPT2 in carnitine shuttle were lower in NT1 (p = 0.000051 and p = 0.00014, respectively).

Conclusions

These results provide evidences that abnormal fatty acid metabolism is involved in the pathophysiology of NT1 and other hypersomnia.

The frequencies of very long-chain acyl-CoA dehydrogenase deficiency genetic variants in Japan have changed since the implementation of expanded newborn screening

Very long-chain acyl-CoA dehydrogenase (VLCAD) deficiency has been a target of expanded newborn screening (ENBS) using tandem mass spectrometry in Japan. Since the implementation of ENBS, a number of novel ACADVL variants responsible for VLCAD deficiency have been identified. In this study, genotypic differences in Japanese patients with VLCAD deficiency were investigated before and after ENBS. The ACADVL variants in 61 subjects identified through ENBS (ENBS group) and in 40 patients who subsequently developed clinical symptoms without undergoing ENBS (pre-ENBS group) were compared. Subjects in the ENBS group underwent genetic testing and/or VLCAD enzyme activity measurements. Patients in the pre-ENBS group were stratified into three clinical phenotypes and underwent genetic testing. This study revealed that the variants p.K264E, p.K382Q and c.996dupT were found in both groups, but their frequencies were lower in the ENBS group (5.2%, 3.1% and 4.2%, respectively) than in the pre-ENBS group (16.5%, 12.7% and 10.1%, respectively). In addition, p.C607S, p.T409M, p.M478I, p.G289R, p.C237R, p.T260M, and p.R229* were exclusively identified in the ENBS group. Among these variants, p.C607S exhibited the highest frequency (18.8%). The patients who were heterozygous for p.C607S demonstrated 7-42% of control enzyme activity. p.C607S is suspected to be unique to Japanese individuals. According to a comparison of enzyme activity, patients with the p.C607S variant may exhibit higher enzyme activity than those with the p.A416T, p.A180T, p.R450H, and p.K264E variants, which are responsible for the myopathic form of the disease. The VLCAD deficiency genotypes have changed since the initiation of ENBS in Japan.

Pilot Study on Neonatal Screening for Methylmalonic Acidemia Caused by Defects in the Adenosylcobalamin Synthesis Pathway and Homocystinuria Caused by Defects in Homocysteine Remethylation

Neonatal screening (NS) for methylmalonic acidemia uses propionylcarnitine (C3) as a primary index, which is insufficiently sensitive at detecting methylmalonic acidemia caused by defects in the adenosylcobalamin synthesis pathway. Moreover, homocystinuria from cystathionine β-synthase deficiency is screened by detecting hypermethioninemia, but methionine levels decrease in homocystinuria caused by defects in homocysteine remethylation. To establish NS detection of methylmalonic acidemia and homocystinuria of these subtypes, we evaluated the utility of indices (1) C3 ≥ 3.6 μmol/L and C3/acetylcarnitine (C2) ≥ 0.23, (2) C3/methionine ≥ 0.25, and (3) methionine < 10 μmol/L, by retrospectively applying them to NS data of 59,207 newborns. We found positive results in 116 subjects for index (1), 37 for (2), and 15 for (3). Second-tier tests revealed that for index 1, methylmalonate (MMA) was elevated in two cases, and MMA and total homocysteine (tHcy) were elevated in two cases; for index 2 that MMA was elevated in one case; and for index 3 that tHcy was elevated in one case. Though data were anonymized, two cases identified by index 1 had been diagnosed with maternal vitamin B₁₂ deficiency during NS. Methylene tetrahydrofolate reductase deficiency was confirmed for the case identified by index 3, which was examined because an elder sibling was affected by the same disease. Based on these data, a prospective NS study is underway.

Urea cycle disorders in India: clinical course, biochemical and genetic investigations, and prenatal testing

Background

Urea cycle disorders (UCDs) are inherited metabolic disorders that present with hyperammonemia, and cause significant mortality and morbidity in infants and children. These disorders are not well reported in the Indian population, due to lack of a thorough study of the clinical and molecular profile.

Results

We present data from two major metabolic centres in India, including 123 cases of various UCDs. The majority of them (72/123, 58%) presented in the neonatal period (before 30 days of age) with 88% on or before day 7 of life (classical presentation), and had a high mortality (64/72, 88%). Citrullinemia type 1 was the most common UCD, observed in 61/123 patients. Ornithine transcarbamylase (OTC) deficiency was the next most common, seen in 24 cases. Argininosuccinic aciduria was diagnosed in 20 cases. Deficiencies of arginase, N-acetylglutamate synthase, carbamoyl phosphate synthetase, citrin, and lysinuric protein intolerance were also observed.

Molecular genetic analysis revealed two common ASS1 mutations: c.470G > A (p.Arg157His) and c.1168G > A (p.Gly390Arg) (36 of 55 tested patients). In addition, few recurrent point mutations in ASL gene, and a deletion of the whole OTC gene were also noted. A total of 24 novel mutations were observed in the various genes studied. We observed a poor clinical outcome with an overall all time mortality of 63% (70/110 cases with a known follow-up), and disability in 70% (28/40) among the survivors. Prenatal diagnosis was performed in 30 pregnancies in 25 families, including one pre-implantation genetic diagnosis.

Conclusions

We report the occurrence of UCDs in India and the spectrum that may be different from the rest of the world. Citrullinemia type 1 was the most common UCD observed in the cohort. Increasing awareness amongst clinicians will improve outcomes through early diagnosis and timely treatment. Genetic diagnosis in the proband will enable prenatal/pre-implantation diagnosis in subsequent pregnancies.

Electronic supplementary material

The online version of this article (10.1186/s13023-018-0908-1) contains supplementary material, which is available to authorized users.

A variant at 9q34.11 is associated with HLA-DQB1*06:02 negative essential hypersomnia

Essential hypersomnia (EHS) is a lifelong disorder characterized by excessive daytime sleepiness without cataplexy. EHS is associated with human leukocyte antigen (HLA)-DQB1*06:02, similar to narcolepsy with cataplexy (narcolepsy). Previous studies suggest that DQB1*06:02-positive and -negative EHS are different in terms of their clinical features and follow different pathological pathways. DQB1*06:02-positive EHS and narcolepsy share the same susceptibility genes. In the present study, we report a genome-wide association study with replication for DQB1*06:02-negative EHS (408 patients and 2247 healthy controls, all Japanese). One single-nucleotide polymorphism, rs10988217, which is located 15-kb upstream of carnitine O-acetyltransferase (CRAT), was significantly associated with DQB1*06:02-negative EHS (P = 7.5 × 10^-9, odds ratio = 2.63). The risk allele of the disease-associated SNP was correlated with higher expression levels of CRAT in various tissues and cell types, including brain tissue. In addition, the risk allele was associated with levels of succinylcarnitine (P = 1.4 × 10^-18) in human blood. The leading SNP in this region was the same in associations with both DQB1*06:02-negative EHS and succinylcarnitine levels. The results suggest that DQB1*06:02-negative EHS may be associated with an underlying dysfunction in energy metabolic pathways.

Acute encephalopathy with biphasic seizures and late reduced diffusion associated with Streptococcus sanguinis sepsis

Acute encephalopathy with biphasic seizures and late reduced diffusion (AESD) develops in association with systemic as well as central nervous system (CNS) viral or bacterial infections. AESD is most often noted with influenza or human herpesvirus 6 infection in previously healthy infants. However, AESD has also been reported in an infant with developmental retardation and in a mentally and motor-disabled adolescent. Here, we report the case of a 4- year-old female with significant development delay due to spinal muscular atrophy, who developed AESD during Streptococcus sanguinis sepsis with no apparent CNS infection. Although the patient had extremely high serum procalcitonin (45.84 ng/mL, reference; <0.4) on admission indicating a poor prognosis, she was successfully managed for sepsis and AESD.

National survey of Japanese patients with mevalonate kinase deficiency reveals distinctive genetic and clinical characteristics

OBJECTIVES

Mevalonate kinase deficiency (MKD), a rare autosomal recessive autoinflammatory syndrome, is caused by disease-causing variants of the mevalonate kinase (MVK) gene. A national survey was undertaken to investigate clinical and genetic features of MKD patients in Japan.

METHODS

The survey identified ten patients with MKD. Clinical information and laboratory data were collected from medical records and by direct interviews with patients, their families, and their attending physicians. Genetic analysis and measurement of MVK activity and urinary excretion of mevalonic acid were performed.

RESULTS

None of the 10 patients harbored MVK disease-causing variants that are common in European patients. However, overall symptoms were in line with previous European reports. Continuous fever was observed in half of the patients. Elevated transaminase was observed in four of the 10 patients, two of whom fulfilled the diagnostic criteria for hemophagocytic lymphohistiocytosis. About half of the patients responded to temporary administration of glucocorticoids and NSAIDs; the others required biologics such as anti-IL-1 drugs.

CONCLUSION

This is the first national survey of MKD patients in a non-European country. Although clinical symptoms were similar to those reported in Europe, the incidence of continuous fever and elevated transaminase was higher, probably due to differences in disease-causing variants.

Newborn screening for carnitine palmitoyltransferase II deficiency using (C16+C18:1)/C2: Evaluation of additional indices for adequate sensitivity and lower false-positivity

BACKGROUND

Carnitine palmitoyltransferase (CPT) II deficiency is one of the most common forms of mitochondrial fatty acid oxidation disorder (FAOD). However, newborn screening (NBS) for this potentially fatal disease has not been established partly because reliable indices are not available.

METHODS

We diagnosed CPT II deficiency in a 7-month-old boy presenting with hypoglycemic encephalopathy, which apparently had been missed in the NBS using C16 and C18:1 concentrations as indices. By referring to his acylcarnitine profile from the NBS, we adopted the (C16+C18:1)/C2 ratio (cutoff 0.62) and C16 concentration (cutoff 3.0nmol/mL) as alternative indices for CPT II deficiency such that an analysis of a dried blood specimen collected at postnatal day five retroactively yielded the correct diagnosis. Thereafter, positive cases were assessed by measuring (1) the fatty acid oxidation ability of intact lymphocytes and/or (2) CPT II activity in the lysates of lymphocytes. The diagnoses were then further confirmed by genetic analysis.

RESULTS

The disease was diagnosed in seven of 21 newborns suspected of having CPT II deficiency based on NBS. We also analyzed the false-negative patient and five symptomatic patients for comparison. Values for the NBS indices of the false-negative, symptomatic patient were lower than those of the seven affected newborns. Although it was difficult to differentiate the false-negative patient from heterozygous carriers and false-positive subjects, the fatty acid oxidation ability of the lymphocytes and CPT II activity clearly confirmed the diagnosis. Among several other indices proposed previously, C14/C3 completely differentiated the seven NBS-positive patients and the false-negative patient from the heterozygous carriers and the false-positive subjects. Genetic analysis revealed 16 kinds of variant alleles. The most prevalent, detected in ten alleles in nine patients from eight families, was c.1148T>A (p.F383Y), a finding in line with those of several previous reports on Japanese patients.

CONCLUSIONS

These findings suggested that CPT II deficiency can be screened by using (C16+C18:1)/C2 and C16 as indices. An appropriate cutoff level is required to achieve adequate sensitivity albeit at the cost of a considerable increase in the false-positive rate, which might be reduced by using additional indices such as C14/C3.

Screening of MCAD deficiency in Japan: 16years' experience of enzymatic and genetic evaluation

BACKGROUND

Medium-chain acyl-CoA dehydrogenase (MCAD) deficiency is a representative disorder of fatty acid oxidation and is one of the most prevalent inborn errors of metabolism among Caucasian populations. In Japan, however, it was as late as 2000 when the first patient was found, and enzymatic and genetic evaluation of MCAD deficiency began.

METHODS

We measured octanoyl-CoA dehydrogenase activity in lymphocytes of symptomatic children and newborn screening (NBS)-positive subjects who showed elevated levels of C8-acylcarnitine in blood. The results were further confirmed by direct sequencing of the ACADM gene.

RESULTS

The disease was diagnosed in 9 out of 18 symptomatic children. The affected patients showed residual activities from 0% to 3% of the normal average value, except for one patient with 10% activity. Concerning 50 NBS-positive subjects, 18 with enzymatic activities around 10% or lower and 14 with activities ranging from 13% to 30% were judged to be affected patients, and biallelic variants were detected in most of the cases tested. Newborns with higher enzymatic activities were estimated to be heterozygous carriers or healthy subjects, though biallelic variants were detected in 5 of them. Genetic analysis detected 22 kinds of variant alleles. The most prevalent was c.449_452delCTGA (p.T150Rfs), which was followed by c.50G>A (p.R17H), c.1085G>A (p.G362E), c.157C>T (p.R53C), and c.843A>T (p.R281S); these five variants accounted for approximately 60% of all the alleles examined.

CONCLUSION

Our study has revealed the unique genetic backgrounds of MCAD deficiency among Japanese, based on the largest series of non-Caucasian cases. A continuous spectrum of severity was also observed in our series of NBS-positive cases, suggesting that it is essential for every nation and ethnic group to accumulate its own information on gene variants, together with their enzymatic evaluation, in order to establish an efficient NBS system for MCAD deficiency.

Evaluation of dural sinus invasion and extension of extra-axial intracranial tumors: The advantages of a high-resolution postcontrast 3-D gradient-echo technique

Objective: To assess the usefulness of a postcontrast 3-D Fourier transform (3DFT) gradient-echo (GRE) technique in dural sinus invasion and extension of extraaxial intracranial tumors in comparison with a conventional spin-echo (SE) technique.

Material and Methods: Fourteen consecutive patients with 15 extra-axial tumors in contiguity with the dural sinus, including 14 meningiomas and 1 adenoid cystic carcinoma, underwent postcontrast T1-weighted SE and GRE MR studies. Detectability of dural sinus invasion and extension was evaluated using two sequences by two neuroradiologists in a blinded manner and compared with surgical results. Quantitative analysis was also performed to calculate the contrast-to-noise ratio (CNR) between lesion and dural sinus on SE and GRE images. The data were analyzed statistically using a matched paired t-test.

Results: In the qualitative evaluation, the detectability of dural sinus invasion in 3DFT-GRE images was superior to that using SE images. The mean CNR for all lesions was 3.86 on SE images and 5.63 on 3DFT-GRE images ( p = 0.03).

Conclusion: For evaluation of dural sinus invasion and the extension of extra-axial tumors, postcontrast 3DFT-GRE MR images were superior to conventional SE images.

Seventeen Novel Mutations in PCCA and PCCB Genes in Indian Propionic Acidemia Patients, and Their Outcomes

AIMS

The goal of this study was to identify mutations in the propionyl-CoA carboxylase alpha subunit (PCCA) and propionyl-CoA carboxylase beta subunit (PCCB) genes, and to assess their effects on propionic academia (PA) patients.

METHODOLOGY

Twenty-five Indian children with PA were enrolled in this study. Bidirectional Sanger sequencing was performed on both the coding and flanking regions of the PCCA and PCCB genes and the chromatograms were analyzed. Bioinformatic tools were used to classify novel variations into pathogenic or benign.

RESULTS

The majority of the cases (19/25, 76%) were of the early-onset (<90 days of age) type and 5 were of the late-onset type. The majority of patients had mutations in the PCCA gene (18/25). A total of 26 mutations were noted: 20 in the PCCA gene and 6 in PCCB gene. Seventeen mutations were novel (14 in PCCA and 3 in PCCB). The SNP c.937C>T (p.Arg313Ter), was noted in 9/36 (25%) alleles in the PCCA gene. All of the children were symptomatic and only three survived who are doing well with no major disabilities.

CONCLUSION

The spectrum of mutations in the PCCA and PCCB genes among Indians is distinct from other populations. The absence of a common mutation signifies the heterogeneity and admixture of various subpopulations. These findings also suggest that individuals of Indian origin may not benefit from the mutation-based "carrier screening panels" offered by many genetic laboratories.

Significance of ACADM mutations identified through newborn screening of MCAD deficiency in Japan

BACKGROUND

Since the first case was detected in 2000, there has been a remarkable increase in Japanese patients diagnosed with medium-chain acyl-CoA dehydrogenase (MCAD) deficiency. Genetic analysis has revealed a spectrum of mutations that is quite different from those observed in Caucasian populations. In 2014, Japan initiated nationwide newborn screening (NBS) for MCAD using tandem mass spectrometry (MS/MS). It is an urgent issue to assess the risk of acute metabolic decompensation from the respective novel mutations found thus far.

METHODS

To evaluate the pathogenic effect of each mutation, we established a eukaryotic cell expression system and prepared 11 mutant proteins identified in five symptomatic patients and eight MS/MS-NBS-positive newborns, as well as two common Caucasian mutations, p.K329E (c.985G>A) and p.Y67H (c.157C>T) for comparison.

RESULTS

The expression of four mutant proteins (p.Q45R, p.P92L, p.P128X and p.Y397N) were severely impaired, whereas the others expressed normally, as did p.K329E and p.Y67H. Based on their dehydrogenase activities toward n-octanoyl-CoA, we determined three mutations (p.R53C, p.R281S and p.G362E) to be disease-causing, two mutations having (p.R17H and p.M274V) to be of marginal risk, and two mutations (p.K271E and p.I416T) as benign. Their allele-specific activities were as a whole in accordance with those estimated from the results of measurement in peripheral blood mononuclear cells.

CONCLUSION

As most of the mutations detected in the Japanese population are unique, prudent genetic and enzymatic analysis is essential to precisely evaluate the latent risk of clinical onset for screening-positive newborns.

High incorporation of long-chain fatty acids contributes to the efficient production of acylated ghrelin in ghrelin-producing cells

The mechanisms for supplying octanoic acid for ghrelin acylation in X/A-like cells are incompletely understood. We found that long-chain fatty acids were incorporated at a higher rate in the ghrelin-producing cell line MGN3-1 than in MIN6 cells, in part due to higher expression level of long-chain fatty acyl-CoA synthetase family member 1 (Acsl1). Inhibition of ACSLs by triacsin C profoundly suppressed acylated ghrelin production. These results suggest that high incorporation of long-chain fatty acids into the ghrelin-producing cells plays a role in the supply of octanoic acid for ghrelin acylation.

Clinical, biochemical and molecular investigation of adult-onset glutaric acidemia type II: Characteristics in comparison with pediatric cases

INTRODUCTION

An increasing number of adult patients have been diagnosed with fatty acid β-oxidation disorders with the rising use of diagnostic technologies. In this study, clinical, biochemical, and molecular characteristics of 2 Japanese patients with adult-onset glutaric acidemia type II (GA2) were investigated and compared with those of pediatric cases.

METHODS

The patients were a 58-year-old male and a 31-year-old male. In both cases, episodes of myopathic symptoms, including myalgia, muscle weakness, and liver dysfunction of unknown cause, had been noted for the past several years. Muscle biopsy, urinary organic acid analysis (OA), acylcarnitine (AC) analysis in dried blood spots (DBS) and serum, immunoblotting, genetic analysis, and an in vitro probe acylcarnitine (IVP) assay were used for diagnosis and investigation.

RESULTS

In both cases, there was no obvious abnormality of AC in DBS or urinary OA, although there was a increase in medium- and long-chain ACs in serum; also, fat deposits were observed in the muscle biopsy. Immunoblotting and gene analysis revealed that both patients had GA2 due to a defect in electron transfer flavoprotein dehydrogenase (ETFDH). The IVP assay indicated no special abnormalities in either case.

CONCLUSION

Late-onset GA2 is separated into the intermediate and myopathic forms. In the myopathic form, episodic muscular symptoms or liver dysfunction are primarily exhibited after later childhood. Muscle biopsy and serum (or plasma) AC analysis allow accurate diagnosis in contrast with other biochemical tests, such as analysis of AC in DBS, urinary OA, or the IVP assay, which show fewer abnormalities in the myopathic form compared to intermediate form.

White matter abnormalities in an adult patient with l-2-hydroxyglutaric aciduria

l-2-Hydroxyglutaric aciduria (l-2-HGA) is a rare inborn error of metabolism. Mainly, patients with this disorder exhibit neurological symptoms and characteristic neuroradiological findings, such as subcortical white matter abnormalities, which are believed to be caused by the toxicity of the accumulation of l-2-hydroxyglutaric acid. A genotype-first approach of the whole exome sequence was used to identify compound heterozygous mutations, c.584A>G (p.Y195C) and c.772T>C (p.C258R), in L2HGDH, the gene responsible for this disorder, in an adult patient with intellectual disability and intractable epilepsy. A retrospective assay confirmed the increased concentrations of 2-hydroxyglutaric acid in the urine. These results suggested that neuroradiological findings of subcortical white matter abnormalities are characteristic of l-2-HGA and that clinical exome sequencing has sufficient power to compensate for insufficient clinical evaluations.

Inborn errors of ketone body utilization

Succinyl-CoA:3-ketoacid CoA transferase (SCOT) deficiency and mitochondrial acetoacetyl-CoA thiolase (beta-ketothiolase or T2) deficiency are classified as autosomal recessive disorders of ketone body utilization characterized by intermittent ketoacidosis. Patients with mutations retaining no residual activity on analysis of expression of mutant cDNA are designated as severe genotype, and patients with at least one mutation retaining significant residual activity, as mild genotype. Permanent ketosis is a pathognomonic characteristic of SCOT-deficient patients with severe genotype. Patients with mild genotype, however, may not have permanent ketosis, although they may develop severe ketoacidotic episodes similar to patients with severe genotype. Permanent ketosis has not been reported in T2 deficiency. In T2-deficient patients with severe genotype, biochemical diagnosis is done on urinary organic acid analysis and blood acylcarnitine analysis to observe characteristic findings during both ketoacidosis and non-episodic conditions. In Japan, however, it was found that T2-deficient patients with mild genotype are common, and typical profiles were not identified on these analyses. Based on a clinical study of ketone body utilization disorders both in Japan and worldwide, we have developed guidelines for disease diagnosis and treatment. These diseases are treatable by avoiding fasting and by providing early infusion of glucose, which enable the patients to grow without sequelae.

Citrin deficiency: A treatable cause of acute psychosis in adults

Citrin deficiency is an autosomal recessive genetic disorder caused by a defect in the mitochondrial aspartate/glutamate antiporter, citrin. The disorder manifests either as neonatal intra-hepatic cholestasis or occurs in adulthood with recurrent hyperammonemia and neuropsychiatric disturbances. It has a high prevalence in the East Asian population, but is actually pan-ethnic. We report the case of a 26-year-old male patient presenting with episodes of abnormal neuro-psychiatric behavior associated with hyperammonemia, who was diagnosed to be having citrin deficiency. Sequencing of the SLC25A13 gene revealed two novel mutations, a single base pair deletion, c. 650delT (p.Phe217SerfsFNx0133) in exon 7, and a missense mutation, c. 869T>C (p.Ile290Thr) in exon 9. Confirmation of the diagnosis allowed establishment of the appropriate management. The latter is an essential pre-requisite for obtaining a good prognosis as well as for family counseling.

The first case in Asia of 2-methyl-3-hydroxybutyryl-CoA dehydrogenase deficiency (HSD10 disease) with atypical presentation

2-Methyl-3-hydroxybutyryl-CoA dehydrogenase (2M3HBD) deficiency (HSD10 disease) is a rare inborn error of metabolism, and <30 cases have been reported worldwide. This disorder is typically characterized by progressive neurodegenerative disease from 6 to 18 months of age. Here, we report the first patient with this disorder in Asia, with atypical clinical presentation. A 6-year-old boy, who had been well, presented with severe ketoacidosis following a 5-day history of gastroenteritis. Urinary organic acid analysis showed elevated excretion of 2-methyl-3-hydroxybutyrate and tiglylglycine. He was tentatively diagnosed with β-ketothiolase (T2) deficiency. However, repeated enzyme assays using lymphocytes showed normal T2 activity and no T2 mutation was found. Instead, a hemizygous c.460G>A (p.A154T) mutation was identified in the HSD17B10 gene. This mutation was not found in 258 alleles from Japanese subjects (controls). A normal level of the HSD17B10 protein was found by immunoblot analysis but no 2M3HBD enzyme activity was detected in enzyme assays using the patient's fibroblasts. These data confirmed that this patient was affected with HSD10 disease. He has had no neurological regression until now. His fibroblasts showed punctate and fragmented mitochondrial organization by MitoTracker staining and had relatively low respiratory chain complex IV activity to those of other complexes.

Distinguishing imaging features between spinal hyperplastic hematopoietic bone marrow and bone metastasis

BACKGROUND AND PURPOSE

Systematic investigations of the distinguishing imaging features between spinal hyperplastic hematopoietic bone marrow and bone metastasis have not been reported, to our knowledge. The purpose of this study was to determine the distinguishing imaging features of the 2 entities.

MATERIALS AND METHODS

We retrospectively reviewed the radiologic images of 8 consecutive male patients (age range, 52-78 years; mean, 64 years) with suspected spinal metastasis on MR imaging and FDG-PET, which was later confirmed as hyperplastic hematopoietic bone marrow. MR imaging, FDG-PET, CT, and bone scintigraphy images were qualitatively and/or quantitatively evaluated. Imaging findings in 24 patients with spinal metastasis were compared, and differences were statistically analyzed.

RESULTS

All 8 vertebral hyperplastic hematopoietic bone marrow lesions were hypointense on T1- and T2-weighted images; lesions contiguous with the adjacent vertebra were significantly more often seen in hyperplastic hematopoietic bone marrow than in metastasis (P = .035). T2 signal intensity of the lesion was significantly different between the 2 entities (P = .033). FDG-PET showed slightly higher uptake in all hyperplastic hematopoietic bone marrow lesions; their maximum standard uptake value was significantly lower than that of metastatic lesions (P = .037). CT attenuation of hyperplastic hematopoietic bone marrow was equal to or slightly higher than that of adjacent normal-appearing vertebra; the CT appearances of hyperplastic hematopoietic bone marrow and metastasis were significantly different (P < .01). Bone scintigraphy showed normal uptake for all vertebrae with hyperplastic hematopoietic bone marrow; the uptake was significantly different from that of metastasis (P < .01).

CONCLUSIONS

If a lesion was isointense to hyperintense to normal-appearing marrow on MR imaging or had a maximum standard uptake value of >3.6, the lesion was considered metastatic. A normal appearance on CT or bone scintigraphy excluded metastasis.

Biotin and carnitine deficiency due to hypoallergenic formula nutrition in infants with milk allergy

Amino acid formulas and hydrolyzed formulas given to infants in Japan with milk allergies theoretically contain little, if any, biotin and carnitine. We assessed biotin and carnitine insufficiency in six infants with milk allergy who were fed amino acid formulas and/or hydrolyzed formulas, by measuring urine 3-hydroxyisovaleric acid (3-HIA) and serum free carnitine (C0), respectively. All patients presented with elevated urine 3-HIA and lowered serum C0 compared with post-menstrual age-matched infants who were fed breast milk or standard infant formulas. Supplementation with biotin and L-carnitine immediately improved the insufficiency. Care should be taken to avoid biotin and carnitine deficiency in allergic infants fed amino acid or hydrolyzed formulas.

VLCAD deficiency in a patient who recovered from ventricular fibrillation, but died suddenly of a respiratory syncytial virus infection

VLCAD deficiency is an autosomal recessive disorder caused by a defect of fatty acid oxidation. The phenotype is classified into three clinical forms on the basis of the onset of symptoms: a severe form with neonatal onset; a milder form with childhood onset; and a late-onset form. The neonatal form is the most common, and has a higher mortality rate than the others. We report the case of a newborn infant with VLCAD deficiency who developed ventricular fibrillation, which was successfully treated by intensive care, but who suddenly died after a respiratory syncytial virus infection. Early institution of i.v. glucose treatment and active immunization with vaccine, such as palivizumab (anti-RSV mAb), may be important to reduce the frequency and severity of life-threatening episodes.

Comparison of dynamic contrast-enhanced 3T MR and 64-row multidetector CT angiography for the localization of spinal dural arteriovenous fistulas

BACKGROUND AND PURPOSE

For the localization of spinal dural arteriovenous fistulas, it is not determined whether dynamic contrast-enhanced MRA is more reliable than multidetector CTA. The aim of this study was to compare the agreement between intra-arterial DSA, dynamic contrast-enhanced MRA at 3T, and 64-row multidetector CTA for the localization of spinal dural arteriovenous fistulas.

MATERIALS AND METHODS

We enrolled 12 consecutive patients (11 men, 1 woman; age range, 46-83 years; mean, 65 years) who underwent preoperative dynamic contrast-enhanced MRA at 3T and 64-row multidetector CTA. The spinal dural arteriovenous fistula location was confirmed by intra-arterial DSA as the reference standard. Two reviewers independently evaluated the level of the artery feeding the spinal dural arteriovenous fistula on the basis of continuity between the feeder and abnormal spinal vessels on 3T dynamic contrast-enhanced MRA and 64-row multidetector CTA images. Interobserver and intermodality agreement was determined by calculation of the κ coefficient.

RESULTS

On DSA, the vessel feeding the spinal dural arteriovenous fistula was the intercostal artery (7 cases), the lumbar artery (3 cases), and the internal iliac artery or the ascending pharyngeal artery (1 case each). For the fistula level, interobserver agreement was excellent for 3T dynamic contrast-enhanced MRA (κ = 0.97; 95% CI, 0.92-1.00) and very good for 64-row multidetector CTA (κ = 0.84; 95% CI, 0.72-0.96). Intermodality agreement with DSA was good for 3T dynamic contrast-enhanced MRA (κ = 0.78; 95% CI, 0.49-1.00) and moderate for 64-row multidetector CTA (κ = 0.41; 95% CI, 0.020-0.84).

CONCLUSIONS

For the localization of spinal dural arteriovenous fistulas, 3T dynamic contrast-enhanced MRA may be more reliable than 64-row multidetector CTA.

Biotin and carnitine profiles in preterm infants in Japan

BACKGROUND

Biotin plays an important role as a covalently bound coenzyme for carboxylases. Carnitine is essential in β-oxidation to transport long-chain fatty acids across the inner mitochondrial membrane. The present study was conducted to assess the risk of biotin and carnitine deficiencies in preterm infants who received enteral feeding with maternal milk and/or standard infant formula made in Japan.

METHODS

Forty-six infants were enrolled in the study. Urine and serum samples and dried blood spots were collected at 1 week and 1 month of age. Additionally, samples were collected at 40 and 44 weeks post-menstrual age (PMA) in preterm infants. Free carnitine and C5-OH acylcarnitine, which consist of 3-hydroxyisovalerylcarnitine as a major isomer, were measured in serum samples and dried blood spots using tandem mass spectrometry. Urine 3-hydroxyisovaleric acid (3-HIVA) was measured using gas chromatography/mass spectrometry.

RESULTS

The free carnitine levels in preterm infants were significantly lower than those in term infants, but increased with PMA in serum samples and dried blood spots. C5-OH acylcarnitine and urinary 3-HIVA levels, which were very low in term infants, were increased with PMA in preterm infants.

CONCLUSION

The present results may indicate chronic biotin deficiency in preterm infants fed maternal milk and/or standard infant formula. Analyses of carnitine profiles of dried blood spots and urine 3-HIVA are relatively non-invasive and useful for the early detection of biotin deficiency in preterm infants.

Acute severe encephalopathy related to human herpesvirus-6 infection in a patient with carnitine palmitoyltransferase 2 deficiency carrying thermolabile variants

We describe a male infant with carnitine palmitoyltransferase 2 (CPT2) deficiency who presented with acute encephalopathy related to human herpesvirus-6 (HHV-6) infection. He was hospitalized for pylexia and status epilepticus, diagnosed with acute encephalopathy, and treated with intensive supportive care including mechanical ventilation, support for hypothermia, and control of the intracranial pressure, that caused severe neurological sequelae. HHV-6 was detected in his cerebrospinal fluid, indicating HHV-6 related encephalopathy. In the acute phase, acylcarnitine analysis of blood suggested a defect of long chain fatty acid β-oxidation, and CPT2 deficiency was genetically confirmed. In addition, other gene alterations that have been previously reported as "thermolabile variants" were found. Some patients with the infantile form of CPT2 deficiency present with acute encephalopathy, but others do not develop encephalopathy. The correlation between phenotype and genotype has not been clarified. Our case may contribute to the elucidation of the genetic factor involved in acute encephalopathy in CPT2 deficiency.

Small Indian mongooses and masked palm civets serve as new reservoirs of Bartonella henselae and potential sources of infection for humans

The prevalence and genetic properties of Bartonella species were investigated in small Indian mongooses and masked palm civets in Japan. Bartonella henselae, the causative agent of cat-scratch disease (CSD) was isolated from 15.9% (10/63) of the mongooses and 2.0% (1/50) of the masked palm civets, respectively. The bacteraemic level ranged from 3.0 × 10¹ to 8.9 × 10³ CFU/mL in mongooses and was 7.0 × 10³ CFU/mL in the masked palm civet. Multispacer typing (MST) analysis based on nine intergenic spacers resulted in the detection of five MST genotypes (MSTs 8, 14, 37, 58 and 59) for the isolates, which grouped in lineage 1 with MST genotypes of isolates from all CSD patients and most of the cats in Japan. It was also found that MST14 from the mongoose strains was the predominant genotype of cat and human strains. This is the first report on the isolation of B. henselae from small Indian mongooses and masked palm civets. The data obtained in the present study suggest that these animals serve as new reservoirs for B. henselae, and may play a role as potential sources of human infection.

Can 3T MR angiography replace DSA for the identification of arteries feeding intracranial meningiomas?

BACKGROUND AND PURPOSE

For identifying the arterial feeders of meningiomas, the usefulness of 3D TOF MRA at 3T has not been systematically investigated. This study was intended to assess whether unenhanced 3D TOF MRA at 3T can replace DSA for the identification of arteries feeding intracranial meningiomas and whether it is useful for assessing their dural attachment.

MATERIALS AND METHODS

Twenty-one consecutive patients with intracranial meningiomas (18 women, 3 men; aged 42-77 years, mean 57 years) underwent DSA, conventional MR imaging, and 3D TOF MRA. Two neuroradiologists independently evaluated the primary and secondary feeders of each tumor on maximum-intensity-projection and source MRA images. They also identified the location of dural attachments based on information from MR imaging/MRA images. Interobserver and intermodality agreement was determined by calculating the κ coefficient.

RESULTS

For the identification of primary and secondary feeders on MRA images, interobserver agreement was very good (κ=0.83; 95% CI, 0.66-1.00) and moderate (κ=0.58; 95% CI, 0.34-0.82) and intermodality agreement (consensus reading of MRA versus DSA findings) was excellent (κ=0.94; 95% CI, 0.84-1.00) and good (κ=0.72; 95% CI, 0.51-0.93), respectively. With respect to the dural attachment of meningiomas, interobserver agreement was very good (κ=0.95; 95% CI, 0.84-1.00). The agreement in the diagnosis between MR imaging/MRA and surgery was excellent (κ=1.00).

CONCLUSIONS

Unenhanced 3D TOF MRA at 3T cannot at present supplant DSA for the identification of the feeding arteries of intracranial meningiomas. This information may be useful for evaluating their dural attachment.

Long-term outcome and intervention of urea cycle disorders in Japan

Urea cycle disorders (UCDs) are one of the most frequently inherited metabolic diseases in Japan, with an estimated prevalence of 1 per 50,000 live births. Here, we investigated the clinical manifestations, treatment, and prognosis of 177 patients with UCDs who were evaluated and treated from January 1999 to March 2009. These included 77 cases of neonatal-onset UCDs and 91 cases of late-onset UCDs. The most common UCD was ornithine transcarbamylase deficiency (OTCD), which accounted for 116 out of 177 patients. This result is similar to a previous study performed between 1978 and 1995 in Japan: OTCD accounted for about two-thirds of the total number of UCD cases. We studied the relationship between prognosis and the peak blood ammonia level at the onset in 151 UCD patients. Compared with a previous survey conducted in Japan, we found that a greater number of patients survived without any mental retardation despite their peak blood ammonia levels being greater than 360 μmol/l. The 5-year survival rate of patients with OTCD improved to 86% for those with the neonatal-onset type and to 92% for those with the late-onset type. We hypothesize that the increased survival rate is due to early diagnosis and better treatments that are now available in Japan. It is very important to diagnose and treat UCDs, especially OTCD, when the blood ammonia levels in patients are low. The outcome in patients with low blood ammonia levels was better than that in patients with high blood ammonia levels.

Living-donor liver transplantation for propionic acidemia

Propionic acidemia is a rare autosomal recessive disorder affecting the catabolism of branched-chain amino acids because of a genetic defect in PCC. Despite the improvements in medical treatment with protein restriction, sufficient caloric intake, supplementation of l-carnitine, and metronidazole, patients with the severe form of propionic acidemia have life-threatening metabolic acidosis, hyperammonemia, and cardiomyopathy, which results in serious neurologic sequelae and sometimes death. This study retrospectively reviewed three children with neonatal-onset propionic acidemia who received LDLT. Between November 2005 and December 2010, 148 children underwent LDLT, with an overall patient survival of 90.5%, in our center. Three patients were indicated for transplantation because of propionic acidemia. All recipients achieved a resolution of metabolic derangement and better quality of life with protein restriction and medication, although urine methylcitrate and serum propionylcarnitine levels did not decrease markedly. LT can reduce the magnitude of progressive cardiac/neurologic disability as a result of poor metabolic control. Further evaluation is therefore required to determine the long-term suitability of this treatment modality.

Evaluation of brain and head and neck tumors with 4D contrast-enhanced MR angiography at 3T

BACKGROUND AND PURPOSE

Systematic assessment of brain and head and neck tumors with 4D-CE-MRA at 3T has not been investigated. The purpose of this study was to test the hypothesis that 4D-CE-MRA at 3T can replace DSA in the identification of feeding arteries and tumor stain to plan interventional procedures in hypervascular brain and head and neck tumors.

MATERIALS AND METHODS

Fifteen consecutive patients with brain and head and neck tumors underwent 4D-CE-MRA at 3T and DSA. 4D-CE-MRA combined randomly segmented central k-space ordering, keyhole imaging, SENSE, and half-Fourier imaging. We obtained 30 dynamic scans every 1.9 seconds at an acquired spatial resolution of 0.9 × 0.9 × 1.5 mm; the matrix was 256 × 256. Two independent observers inspected the 4D-CE-MRA images for the main arterial feeders and tumor stain. Interobserver and intermodality agreement was assessed by κ statistics.

RESULTS

For 4D-CE-MRA, the interobserver agreement was fair with respect to the main arterial feeders and very good for the degree of tumor stain (κ = 0.28 and 0.87, respectively). Intermodality agreement was moderate for the main arterial feeders (κ = 0.45) and good for the tumor stain (κ = 0.74).

CONCLUSIONS

Although 4D-CE-MRA may be useful for evaluating tumor stain in hypervascular brain and head and neck tumors, it is not able to replace DSA in planning interventional procedures.

Analysis of plasma ghrelin in patients with medium-chain acyl-CoA dehydrogenase deficiency and glutaric aciduria type II

OBJECTIVE

Ghrelin requires a fatty acid modification for binding to the GH secretagogue receptor. Acylation of the Ser3 residue of ghrelin is essential for its biological activities. We hypothesized that acyl-CoA is the fatty acid substrate for ghrelin acylation. Because serum octanoyl-CoA levels are altered by fatty acid oxidation disorders, we examined circulating ghrelin levels in affected patients.

MATERIALS AND METHODS

Blood levels of acyl (A) and des-acyl (D) forms of ghrelin and acylcarnitine of patients with medium-chain acyl-CoA dehydrogenase (MCAD) deficiency and glutaric aciduria type II (GA2) were measured.

RESULTS

Plasma acyl ghrelin levels and A/D ratios increased in patients with MCAD deficiency or GA2 when compared with normal subjects. Reverse-phase HPLC confirmed that n-octanoylated ghrelin levels were elevated in these patients.

CONCLUSION

Changing serum medium-chain acylcarnitine levels may affect circulating acyl ghrelin levels, suggesting that acyl-CoA is the substrate for ghrelin acylation.

Comparison of 3D FLAIR, 2D FLAIR, and 2D T2-weighted MR imaging of brain stem anatomy

BACKGROUND AND PURPOSE

Although 3D FLAIR imaging visualizes detailed structures of the brain stem, it has not been used to evaluate its normal anatomy. The purpose of this study was to evaluate whether 3D FLAIR images can provide more detailed anatomic information of the brain stem than 2D FLAIR and 2D T2WI.

MATERIALS AND METHODS

We prospectively evaluated MR images in 10 healthy volunteers. 3D and 2D FLAIR images, 2D T2WI, and DTI were obtained on a 3T MR imaging scanner. A VISTA technique was used for 3D FLAIR imaging. White matter tracts and nuclei of the brain stem were determined on 3D and 2D FLAIR images and 2D T2WI by referring to anatomic atlases and DTI color maps. The subjective assessment of the visibility by using a 4-point grading system and the contrast ratio of the structures on 3D and 2D FLAIR images and 2D T2WI were evaluated.

RESULTS

The visibility of the SCP and MCP, DSCP, CST, and CTT was higher on 3D FLAIR images than on 2D T2WI and 2D FLAIR images. The contrast ratio for the CST, SCP, MCP, DSCP, and CTT was significantly different on 3D FLAIR images and 2D T2WI and on 3D FLAIR and 2D FLAIR images; there was no significant difference in contrast ratio for the SCP at the pons on 3D FLAIR and 2D T2WI.

CONCLUSIONS

3D FLAIR images provide detailed anatomic information of the brain stem that cannot be obtained on 2D T2WI and 2D FLAIR images.

Prognostic significance of lymphovascular invasion for patients with stage I non-small cell lung cancer

AIMS

This study retrospectively investigated the clinical significance of lymphovascular invasion (LVI) following a complete resection for stage I non-small cell lung cancer (NSCLC).

METHODS

A total of 226 patients who underwent a complete resection for pathological stage I NSCLC were examined.

RESULTS

Lymphatic invasion was pathologically diagnosed as ly0 in 156 patients, ly1 in 65, and ly2 in 5 patients. The pathological vascular invasion was diagnosed as v0 in 178 patients, v1 in 35, v2 in 10, and v3 in 3 patients. The 5-year survival rate after surgery of the patients with and without lymphatic invasion was 76.8 and 90.6%, respectively. There was a significantly more unfavorable prognosis in patients with lymphatic invasion (p = 0.042). The 5-year survival rate of the patients with vascular invasion was also significantly more unfavorable (67.8%) than that of patients without vascular invasion (90.4%; p = 0.004). LVI was found to significantly correlate with tumor size and the presence of pleural invasion.

CONCLUSION

The LVI of NSCLC is a significant prognostic factor in patients with stage I tumors. In future clinical trials, it is necessary to evaluate the efficacy of adjuvant therapy for the selection of patients according to this criterion.

Quantitative blood flow measurements in gliomas using arterial spin-labeling at 3T: intermodality agreement and inter- and intraobserver reproducibility study

BACKGROUND AND PURPOSE

QUASAR is a particular application of the ASL method and facilitates the user-independent quantification of brain perfusion. The purpose of this study was to assess the intermodality agreement of TBF measurements obtained with ASL and DSC MR imaging and the inter- and intraobserver reproducibility of glioma TBF measurements acquired by ASL at 3T.

MATERIALS AND METHODS

Two observers independently measured TBF in 24 patients with histologically proved glioma. ASL MR imaging with QUASAR and DSC MR imaging were performed on 3T scanners. The observers placed 5 regions of interest in the solid tumor on rCBF maps derived from ASL and DSC MR images and 1 region of interest in the contralateral brain and recorded the measured values. Maximum and average sTBF values were calculated. Intermodality and intra- and interobsever agreement were determined by using 95% Bland-Altman limits of agreement and ICCs.

RESULTS

The intermodality agreement for maximum sTBF was good to excellent on DSC and ASL images; ICCs ranged from 0.718 to 0.884. The 95% limits of agreement ranged from 59.2% to 65.4% of the mean. ICCs for intra- and interobserver agreement for maximum sTBF ranged from 0.843 to 0.850 and from 0.626 to 0.665, respectively. The reproducibility of maximum sTBF measurements obtained by methods was similar.

CONCLUSIONS

In the evaluation of sTBF in gliomas, ASL with QUASAR at 3T yielded measurements and reproducibility similar to those of DSC perfusion MR imaging.

A Study of Surgically Resected Peripheral Non-Small Cell Lung Cancer with a Tumor Diameter of 1.0 CM or Less

Background and Aims:

The widespread use of high resolution computed tomography has increased the number of small peripheral lung cancers. This study reviewed the clinicopathological features of the patients with non-small cell lung cancer (NSCLC) with a tumor diameter of 1 cm or less, in order to explore the adequate management of such small sized lung cancers.

Material and Methods:

This study was a retrospective analysis of consecutive 58 patients (5.3% out of 1095 patients) who underwent a complete resection for a peripheral NSCLC with a diameter of 1.0 cm or less. The clinical features and outcomes were compared with 203 patients with NSCLC with a diameter between 1.1 and 2.0 cm.

Results:

The mean age was 64.5 years and there were 26 males and 32 females. Clinical stage was IA in 57 (98%) and IIIA in 1. Lobectomy was performed in 39 patients, segmentectomy in nine, and nonanatomic wedge resection in ten. Two patients, who underwent systemic lymph node dissection, had mediastinal lymph node metastasis and were diagnosed as pathological stage IIIA; however they did not relapse after surgery. One patient with pathological stage IA papillary adenocarcinoma died due to brain metastases. The five-year overall survival rate and disease free survival rate was 95.0% and 95.3%, respectively. Patients with NSCLC of 1.0 cm or less showed significantly better survival than those with tumors measuring 1.1–2.0 cm in size (p = 0.048).

Discussion:

The indications for avoiding systemic lymph node dissection for operable NSCLC should not be based on the size of the tumor. A small-sized lung cancer might be surgically treated before the tumor enlarges to more than 1.0 cm in size.