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P4.54 Splicing mutations in PNPLA2 gene cause neutral lipid storage disease with asymmetric myopathy with rimmed vacuoles
Abstracts / Neuromuscular Disorders 20 (2010) 596–680
P4.54 Splicing mutations in PNPLA2 gene cause neutral lipid storage disease with asymmetric myopathy with rimmed vacuoles C. Yan, W. Li, Y. Zhao, T. Dai, B. Wen, S. Liu, J. Wu, D. Li Qilu Hospital of Shandong University, Neurology, Jinan, China Neutral lipid storage disease (NLSD) is a rare nonlysosomal, autosomal recessive lipid storage disorder characterized by systemic triacylglyceral deposition in multiple tissues. There are two subtypes of NLSD, NLSDI (NLSD with ichthyosis) and NLSDM (NLSD with myopathy), which are caused by mutations in CGI-58 and ATGL gene respectively. So far, only nine patients with NLSDM from eight families have been reported in Japan and Europe. Most of them were caused by deletion or duplication in PNPLA2 gene. We reported two Chinese NLSDM patients with rimmed vacuoles formation caused by splicing mutation in PNPLA2 gene. Patient 1, a 44-yearold male, was in good health until he experienced difficulty walking and lifting heavy objects at age 41. Muscle weakness and atrophy were asymmetrical and proximally dominant. Patient 2, a 48-yearold women with consanguinous parents, complained of progressive muscle weakness over the past 3 years. Both proximal and distal muscles were asymmetrically involved, but distal muscle weakness and atrophy were more severe. Neck muscle involvement and fasciculation were noticed in each patient. Muscle pathology of these two patients were quite similar, including lipid storage in both types of fibers and most prominent in type one. In addition, rimmed vacuoles were observed scattered in limited regions. Direct sequence of all coding exons of PNPLA2 gene revealed a heterozygous mutations (c.749A>C mutation causing amino acid substitution Q250P and in 50 splicing site, IVS6+2T>C) in patient 1 and homozygous mutation (in 50 splice site, IVS6+1G>T) in patients 2. By RTPCR, only the transcript with c.749A>C mutation was detected in patient 1, indicating the absence of the other transcript resulted from the IVS6+2T>C splicing mutation. For patient 2, both of the transcripts were almost gone according to cDNA analysis.Our data discloses that splicing mutation in PNPLA2 gene may cause neutral lipid storage disease with asymmetric myopathy with rimmed vacuoles doi:10.1016/j.nmd.2010.07.250
P4.55 Molecular genetic analysis in 45 patients with muscle carnitine palmitoyltransferase (CPT) II deficiency P.R. Joshi, S. Zierz, M. Deschauer Martin-Luther-University, Dept. of Neurology, Halle, Germany Carnitine palmitoyltransferase (CPT) II deficiency is the most common inherited disorder of long-chain fatty acid oxidation affecting muscle. There is a lethal neonatal form, a severe infantile hepato-cardio-muscular form and a myopathic form characterized by exerciseinduced myalgia, weakness, and myoglobinuria. Genetic studies have identified a common S113L mutation in the myopathic form. We report on molecular genetic and clinical data in a large cohort of 45 patients (36 index patients) with muscle CPT II deficiency. Twentysix patients were previously described and 19 patients were newly diagnosed. In those 19 patients screening of the S113L, P50H and 413delAG-F448 mutations was performed initially. In patients with biochemical evidence of CPT II deficiency the CPT II gene was sequenced if screening of those three mutations did not identify mutations on both alleles. The S113L mutation was detected in 34 index patients (94%) in at least one allele. The allele frequency of this muta-
675
tion was 0.80. Allele frequencies of the two rather common mutations were 0.05 for the P50H mutation and 0.04 for the 413delAG-F448 mutation. Apart from these three common mutations, 8 other mutations were identified (7 mutations in single cases and one R231W in two cases; all in compound heterozygote form). One mutation – a splice site mutation IVS3+1G>A – was novel extending the list of mutations in patients with CPT II deficiency. However, in one patient who was heterozygous for the S113L mutation no second mutation was identified. Residual enzyme activity in muscle showed only mild reduction suggesting a manifesting heterozygote consistent with moderate symptoms with myalgia and weakness without myoglobinuria after extensive sports. In contrast, 79% of the patients with mutations on both alleles suffered from myoglobinuria. Although the myopathic form is often called adult form, in 61% of the patients, the age of onset was in childhood (1–12 years). doi:10.1016/j.nmd.2010.07.251
P4.56 Early and severe axonal motor neuropathy and cardiomyopathy in a patient with mitochondrial trifunctional protein deficiency A.N. Nascimento Osorio 1, C.O. Ortez 1, A.G. Gutierrez 1, C.J.M. Jimenez-Mallebrera 1, J.G.V. Garcia Villoria 2, T.R. Ribes 2, M.V. Vilaseca 3, J.C. Colomer 1 1
Hospital Sant Joan de Deu, Unidad de patología Neuromuscular, Servicio de Neurologia, Barcelona, Spain, 2 Instituto de Bioquimica Clinica y Genetica Molecular, Barcelona, Spain, 3 Hospital Sant Joan de Deu, Bioquímica, Barcelona, Spain Mitochondrial trifunctional protein (MTP) is a heterocomplex composed by four alpha and four beta subunits that catalyzes three steps in mitochondrial beta-oxidation of fatty acids. MTP deficiency is an autosomal recessive disorder that causes a clinical spectrum of disease ranging from severe infantile cardiomyopathy to mild chronic progressive polyneuropathy. Case report: An 18 months old boy is the first child from non-consanguineous healthy parents. Pregnancy and birth were normal. First, clinical symptoms were noticed at six months of age characterized by mild hypotonia, areflexia and failure to thrive. Developmental milestones were delayed. A systolic cardiac buff was detected at the age of 10 months and a dilated cardiomyopathy was diagnosed. At age of 15 months presented congestive heart failure symptoms requiring hospital admission and diuretic treatment. Physical examination showed normal cognitive and social interactions, growth retardation, wasting and weakness of proximal muscles, hypotonia and areflexia. The patient died at 18 months of age due to an advanced cardiac failure. Biochemical studies showed hyperlactacidemia, decreased plasma free carnitine, normal glucose and CK. Blood spot analysis of the acylcarnitine profile showed an increase of 3hydroxy species: 3-OH-palmitoylcarnitine, 3-OH-linoleylcarnitine and 3-OH-oleylcarnitine. Electromyogram showed a reduced interference pattern, spontaneous positive sharp waves and fibrillations; nerve conduction studies were normal. Muscle biopsy: variation in muscular fibre size and fibre type grouping were observed. In vitro acylcarnitine profiling of fibroblasts incubated with palmitate gave a compatible profile with LCHAD or MTP deficiency; the genetic study is being performed currently. Comments: the presence of early onset of axonal neuropathy associated with cardiomyopathy should make us think about this metabolic disorder to guide the diagnosis and an earlier implementation of therapeutic measures. doi:10.1016/j.nmd.2010.07.252
P4.54 Splicing mutations in PNPLA2 gene cause neutral lipid storage disease with asymmetric myopathy with rimmed vacuoles C. Yan, W. Li, Y. Zhao, T. Dai, B. Wen, S. Liu, J. Wu, D. Li Qilu Hospital of Shandong University, Neurology, Jinan, China Neutral lipid storage disease (NLSD) is a rare nonlysosomal, autosomal recessive lipid storage disorder characterized by systemic triacylglyceral deposition in multiple tissues. There are two subtypes of NLSD, NLSDI (NLSD with ichthyosis) and NLSDM (NLSD with myopathy), which are caused by mutations in CGI-58 and ATGL gene respectively. So far, only nine patients with NLSDM from eight families have been reported in Japan and Europe. Most of them were caused by deletion or duplication in PNPLA2 gene. We reported two Chinese NLSDM patients with rimmed vacuoles formation caused by splicing mutation in PNPLA2 gene. Patient 1, a 44-yearold male, was in good health until he experienced difficulty walking and lifting heavy objects at age 41. Muscle weakness and atrophy were asymmetrical and proximally dominant. Patient 2, a 48-yearold women with consanguinous parents, complained of progressive muscle weakness over the past 3 years. Both proximal and distal muscles were asymmetrically involved, but distal muscle weakness and atrophy were more severe. Neck muscle involvement and fasciculation were noticed in each patient. Muscle pathology of these two patients were quite similar, including lipid storage in both types of fibers and most prominent in type one. In addition, rimmed vacuoles were observed scattered in limited regions. Direct sequence of all coding exons of PNPLA2 gene revealed a heterozygous mutations (c.749A>C mutation causing amino acid substitution Q250P and in 50 splicing site, IVS6+2T>C) in patient 1 and homozygous mutation (in 50 splice site, IVS6+1G>T) in patients 2. By RTPCR, only the transcript with c.749A>C mutation was detected in patient 1, indicating the absence of the other transcript resulted from the IVS6+2T>C splicing mutation. For patient 2, both of the transcripts were almost gone according to cDNA analysis.Our data discloses that splicing mutation in PNPLA2 gene may cause neutral lipid storage disease with asymmetric myopathy with rimmed vacuoles doi:10.1016/j.nmd.2010.07.250
P4.55 Molecular genetic analysis in 45 patients with muscle carnitine palmitoyltransferase (CPT) II deficiency P.R. Joshi, S. Zierz, M. Deschauer Martin-Luther-University, Dept. of Neurology, Halle, Germany Carnitine palmitoyltransferase (CPT) II deficiency is the most common inherited disorder of long-chain fatty acid oxidation affecting muscle. There is a lethal neonatal form, a severe infantile hepato-cardio-muscular form and a myopathic form characterized by exerciseinduced myalgia, weakness, and myoglobinuria. Genetic studies have identified a common S113L mutation in the myopathic form. We report on molecular genetic and clinical data in a large cohort of 45 patients (36 index patients) with muscle CPT II deficiency. Twentysix patients were previously described and 19 patients were newly diagnosed. In those 19 patients screening of the S113L, P50H and 413delAG-F448 mutations was performed initially. In patients with biochemical evidence of CPT II deficiency the CPT II gene was sequenced if screening of those three mutations did not identify mutations on both alleles. The S113L mutation was detected in 34 index patients (94%) in at least one allele. The allele frequency of this muta-
675
tion was 0.80. Allele frequencies of the two rather common mutations were 0.05 for the P50H mutation and 0.04 for the 413delAG-F448 mutation. Apart from these three common mutations, 8 other mutations were identified (7 mutations in single cases and one R231W in two cases; all in compound heterozygote form). One mutation – a splice site mutation IVS3+1G>A – was novel extending the list of mutations in patients with CPT II deficiency. However, in one patient who was heterozygous for the S113L mutation no second mutation was identified. Residual enzyme activity in muscle showed only mild reduction suggesting a manifesting heterozygote consistent with moderate symptoms with myalgia and weakness without myoglobinuria after extensive sports. In contrast, 79% of the patients with mutations on both alleles suffered from myoglobinuria. Although the myopathic form is often called adult form, in 61% of the patients, the age of onset was in childhood (1–12 years). doi:10.1016/j.nmd.2010.07.251
P4.56 Early and severe axonal motor neuropathy and cardiomyopathy in a patient with mitochondrial trifunctional protein deficiency A.N. Nascimento Osorio 1, C.O. Ortez 1, A.G. Gutierrez 1, C.J.M. Jimenez-Mallebrera 1, J.G.V. Garcia Villoria 2, T.R. Ribes 2, M.V. Vilaseca 3, J.C. Colomer 1 1
Hospital Sant Joan de Deu, Unidad de patología Neuromuscular, Servicio de Neurologia, Barcelona, Spain, 2 Instituto de Bioquimica Clinica y Genetica Molecular, Barcelona, Spain, 3 Hospital Sant Joan de Deu, Bioquímica, Barcelona, Spain Mitochondrial trifunctional protein (MTP) is a heterocomplex composed by four alpha and four beta subunits that catalyzes three steps in mitochondrial beta-oxidation of fatty acids. MTP deficiency is an autosomal recessive disorder that causes a clinical spectrum of disease ranging from severe infantile cardiomyopathy to mild chronic progressive polyneuropathy. Case report: An 18 months old boy is the first child from non-consanguineous healthy parents. Pregnancy and birth were normal. First, clinical symptoms were noticed at six months of age characterized by mild hypotonia, areflexia and failure to thrive. Developmental milestones were delayed. A systolic cardiac buff was detected at the age of 10 months and a dilated cardiomyopathy was diagnosed. At age of 15 months presented congestive heart failure symptoms requiring hospital admission and diuretic treatment. Physical examination showed normal cognitive and social interactions, growth retardation, wasting and weakness of proximal muscles, hypotonia and areflexia. The patient died at 18 months of age due to an advanced cardiac failure. Biochemical studies showed hyperlactacidemia, decreased plasma free carnitine, normal glucose and CK. Blood spot analysis of the acylcarnitine profile showed an increase of 3hydroxy species: 3-OH-palmitoylcarnitine, 3-OH-linoleylcarnitine and 3-OH-oleylcarnitine. Electromyogram showed a reduced interference pattern, spontaneous positive sharp waves and fibrillations; nerve conduction studies were normal. Muscle biopsy: variation in muscular fibre size and fibre type grouping were observed. In vitro acylcarnitine profiling of fibroblasts incubated with palmitate gave a compatible profile with LCHAD or MTP deficiency; the genetic study is being performed currently. Comments: the presence of early onset of axonal neuropathy associated with cardiomyopathy should make us think about this metabolic disorder to guide the diagnosis and an earlier implementation of therapeutic measures. doi:10.1016/j.nmd.2010.07.252