- Email: [email protected]
A Novel Nonsense Mutation (515del4) in Muscle Carnitine Palmitoyltransferase II Deficiency
Molecular Genetics and Metabolism 75, 181–185 (2002) doi:10.1006/mgme.2001.3281, available online at http://www.idealibrary.com on
MUTATION REPORT A Novel Nonsense Mutation (515del4) in Muscle Carnitine Palmitoyltransferase II Deficiency Marcus Deschauer,* ,1 Thomas Wieser,* Rolf Schro¨der,† and Stephan Zierz* *Department of Neurology, Martin-Luther-Universita¨t Halle-Wittenberg, Ernst-Grube-Strasse 40, 06097 Halle/Saale, Germany; and †Department of Neurology, Rheinische Friedrich-Wilhelms-Universita¨t Bonn, Sigmund-Freud-Strasse 25, 53105 Bonn, Germany Received November 19, 2001, and in revised form November 26, 2001
in an autosomal recessive trait. The milder muscle form with infantile or adult onset is the most common disorder of lipid metabolism affecting skeletal muscle and the most frequent case of hereditary myoglobinuria. Attacks of exercise-induced muscle pain and weakness, rhabdomyolysis, and paroxysmal myoglobinuria eventually leading to renal failure are the prominent features of this disease. The severe multisystemic infantile form with onset during the first 2 years of life presents with attacks of liver failure with hypoketotic hypoglycemia, cardiomyopathy, or cardiac arrhythmias. Finally it is possible that the multisystemic infantile form manifests neonatally leading to death in the first month (1,2). The human CPT II gene is located at chromosome 1 and spans 20 kb containing 5 exons (3). In patients with the muscle form of CPT II deficiency a common S113L mutation was identified in about 60% of mutant alleles (4,5). Subsequently several rare disease causing mutations were communicated that can be associated with the muscle form of CPT II deficiency. We report on a new nonsense mutation in a patient with a severe course of the muscle form.
We identified a novel nonsense mutation in the carnitine palmitoyltransferase (CPT; EC 2.3.1.21) II gene in a patient with biochemical evidence of CPT II deficiency. The 39-year-old man suffered from the muscle form of CPT II deficiency. Attacks of myalgia and muscle weakness started in childhood and led to renal failure five times. A mild proximal weakness of the lower limbs was left as a residue. Molecular genetic analysis revealed the common S113L mutation on one allele. On the other allele a novel 4-bp deletion starting at codon 515 (515del4) was found leading to frameshift that results in a stop codon 15 codons upstream. Our data further expand the genetic heterogeneity in patients with CPT II deficiency. © 2002 Elsevier Science (USA) Key Words: carnitine palmitoyltransferase II; nonsense mutation.
The carnitine palmitoyltransferase (CPT) system (EC 2.3.1.21) is made up of two proteins, one located in the outer mitochondrial membrane (CPT I) and the other in the inner membrane (CPT II). They are important for the transport of long-chain fatty acids into the mitochondrial matrix. CPT II in contrast to CPT I exists only in one isoform across various tissues and CPT II deficiency presents as different phenotypes that are inherited
CASE REPORT
1 To whom correspondence should be addressed at Klinik und Poliklinik fu¨r Neurologie, Martin-Luther-Universita¨t Halle-Wittenberg, Ernst-Grube-Strasse 40, 06097 Halle/Saale, Germany. Fax: ⫹49 345 557 2020. E-mail: [email protected].
A 39-year-old man complained of attacks with myalgia and muscle weakness starting in childhood after he was sent to school. He had difficulties in sports in school because of muscle pain. Attacks 181 1096-7192/02 $35.00 © 2002 Elsevier Science (USA) All rights reserved.
182
DESCHAUER ET AL.
TABLE 1 Primers and PCR Conditions Primer
PCR conditions
Sense Exon Exon Exon Exon Exon Exon
I II III IVa IVb V
nt nt nt nt nt nt
39 to 63 ⫺65 to ⫺38 (intron 1) ⫺49 to ⫺27 (intron 2) ⫺47 to ⫺21 (intron 3) 1122 to 1144 ⫺56 to ⫺32 (intron 4)
Antisense nt nt nt nt nt nt
76 to 52 (intron 1) 46 to 23 (intron 2) 33 to 6 (intron 3) 1178 to 1152 73 to 48 (intron 4) 2115 to 2091
MgCl 2 1.0 1.5 1.5 1.5 1.5 1.5
Annealing
DMSO
54°C 60°C 58°C 60°C 60°C 60°C
3% — — — — —
mM mM mM mM mM mM
Note. Sequencing primers and amplification conditions for the entire coding region of the CPT II gene. Nucleotide positions for exonic primers according to cDNA sequence published by Finocchiaro et al. (3).
occurred after exercise, exposure to cold, infections, and fasting. Meanwhile he has problems after the slightest exercise. Up to now he had five severe episodes with myoglobinuria leading to acute renal failure and dialysis. None of his family members had similar symptoms. During the last episode with renal failure creatine phosphokinase was elevated to 35000 IU/L. One month later CK was normalized. Neurological examination at this moment revealed a moderate proximal paresis of the lower limbs. The patient had difficulty arising from a squat. Needle EMG of the deltoid and vastus lateralis muscle showed a myopathic pattern. Muscle biopsy showed histologically unspecific myopathic changes with atrophic fibers, increased variability in fiber size, perimysial fibrosis, and fat increase. There was little endomysial lymphatic and mononuclear cell infiltration. METHODS Biochemical Analysis of CPT in Muscle CPT activity in muscle homogenate was determined using the isotope forward assay under optimal conditions, and after preincubation with Triton X-100 (0.5%), and with the addition of malonyl-CoA (0.2 mM) (6,7). Molecular Genetic Studies Genomic DNA was extracted from muscle by standard methods. The common S113L mutation was identified by restriction fragment length polymorphism (RFLP) of polymerase chain reaction (PCR) products with the enzyme BstXI (4). For detection of
new mutations direct sequencing of PCR products was performed. For this purpose the coding region of the CPT II gene was amplified with six matching primer pairs (Table 1). Both strands of the PCR products were sequenced directly with the same primers used for amplification. Sequences were compared with the genomic structure of the CPT II gene according to Finocchiaro et al. (3). RFLP of a 699-bp PCR product containing the first part of exon 4 was performed with the enzyme StuI to confirm a new deletion in exon 4 and to exclude it in controls. Wild-type DNA was cut into fragments of 523 and 176 bp. In contrast deleted DNA was not cut. Fragments were visualized in a 2% agarose gel (Fig. 2). RESULTS Total CPT activity was normal (2.3 nmol ⫻ min ⫺1 ⫻ mg noncollagen protein). Residual activity after preincubation with Triton X-100 was 5% (normal 40.2 ⫾ 3.4%) and with addition of malonyl-CoA 5% (normal 56.7 ⫾ 6.4%). PCR-RFLP revealed that the patient was heterozygous for the S113L mutation. By direct sequencing a novel 4-bp deletion from position 1646 –1649 was observed in the heterozygous state in exon 4. This deletion starting at codon 515 (515del4) leads to a frameshift that results in a stop codon 15 codons upstream (Fig. 1). PCRRFLP confirmed that the patient was heterozygous for this mutation (Fig. 2). PCR-RFLP of the family members showed that the mother was heterozygous for the 515del4 mutation and the father was heterozygous for the S113L mutation. Two of
183
NONSENSE MUTATION 515del4
FIG. 1. Direct sequencing of PCR-amplified genomic DNA of exon 4 of CPT II gene. At codon 515 a 4-bp deletion is starting that deletes the third base of codon 515 (C) and all bases of codon 516 (TTT). The frameshift results in a stop codon 15 codons upstream.
the three asymptomatic brothers of the patient carried the S113L mutation on one allele. The third brother carried none of the mutant alleles
(Fig. 3). The mutation was not found in 110 alleles of 55 normal controls by PCR-RFLP. DISCUSSION Biochemically an abnormal regulation of CPT II was identified as it was shown previously in patients with the muscle form of CPT II deficiency (6,7). The identified 515del4 mutation is likely to be pathogenic for the following reasons: (1) the stop codon results in premature termination of protein translation after 529 amino acids, resulting in a truncated peptide missing 20% of the enzyme mole-
FIG. 2. A 2% agarose gel of a 699-bp PCR product containing the first part of exon 4 after restriction enzyme digestion with StuI. Wild-type DNA was cut into fragments of 523 and 176 bp whereas deleted DNA was not cut. Lane 1: marker. Lane 2: control. Lane 3: index patient.
FIG. 3. Pedigree of the family with genotypes below the symbols. Index patient with filled symbols. Family members with one mutant allele half-filled.
184
DESCHAUER ET AL.
cule; (2) analysis of the parents’ DNA proved that the 515del4 mutation and the S113L mutation are located on different alleles in the index patient; (3) the mutation was absent in 110 alleles of 55 normal controls. Our data further expand the genetic heterogeneity in patients with CPT II deficiency. Up to now 25 mutations in the CPT II gene were communicated (1,8 –11). Seventeen of them can be associated with the muscle form of CPT II deficiency. Bonnefont et al. (1) distinguished between “mild” CPT II mutations leading to the muscle form and “severe” mutations leading to the multisystemic form if they are found in homozygosity. Since CPT II deficiency is an autosomal recessive disorder the presence of a “mild” mutation (e.g., S113L mutation) on one allele and a “severe” mutation (e.g., Y628S mutation) on the other allele seems to result in the muscle form and not the multisystemic form. On the other hand, there is a R631C mutation that does not fit in this classification because it has been reported in the homozygous state with either the muscle form or the multisystemic form (1). Besides the 515del4 mutation three other nonsense mutations were described in patients with the muscle form of CPT II deficiency that result in severe protein truncation. An R124X mutation and a 36 –38insGC mutation were each found in one patient compound heterozygous with the S113L mutation (10,12). A 413delAG-F448L mutation was found in 9 patients compound heterozygous with the S113L mutation (11,13). Homozygosity of the 413delAG-F448L mutation, however, has been found in two sibs with severe multisystemic antenatal presentation (13). This is consistent with the 413delAG-F448L mutation being classified as a severe mutation. It seems to be likely that the 515del4 mutation and the three other nonsense mutations belong to the group of “severe” mutations because nonsense mutations lead to truncated proteins. Missense mutations can be either “mild” or “severe” depending on the functional importance of the exchanged residue. Within the muscle form of CPT II deficiency, frequency and severity of the attacks are variable (2). Our patient showed a rather severe course of the disease with a mild proximal weakness between the attacks. Usually there is no muscle weakness between the attacks (2) but there are also cases with mild proximal limb weakness between the attacks (14,15). Myopathic pattern in EMG and myopathic changes in muscle biopsy underline the incomplete recovery from the attacks in our patient. It must be
elucidated if there is a genotype-phenotype correlation within the muscle form of CPT II deficiency. Possibly patients with a severe mutation on one allele combined with a mild mutation might have earlier onset, more attacks, a lower threshold for developing attacks of myoglobinuria, and persistent weakness than patients who carry mild mutations on both alleles. On the other hand, intrafamilial variability of the disease was observed (16), suggesting that factors other than genotype (e.g., hormonal factors) can modify the clinical picture. REFERENCES 1.
Bonnefont JP, Demaugre F, Prip-Buus C, Saudubray JM, Brivet M, Abadi N, Thuillier L. Carnitine palmitoyltransferase deficiencies. Mol Genet Metab 68:424 – 440, 1999.
2.
Zierz S. Carnitine palmitoyltransferase deficiency. In Myology, 2d ed. (Engel AG, Franzini-Armstrong C, Eds.). New York: McGraw-Hill, pp 1577–1586, 1994.
3.
Finocchiaro G, Taroni F, Rocchi M, Martin AL, Colombo I, Tarelli GT, DiDonato S. cDNA cloning, sequence analysis, and chromosomal localisation of the gene for human carnitine palmitoyltransferase. Proc Natl Acad Sci USA 88:661– 665, 1991.
4.
Taroni F, Verderio E, Dworzak F, Willems PJ, Cavadini P, DiDonato S. Identification of a common mutation in the carnitine palmitoyltransferase II gene in familial recurrent myoglobinuria patients. Nature Genet 4:314 –319, 1993.
5.
Zierz S, Engel AG, Olek K. The Ser113Leu mutation in the carnitine palmitoyltransferase deficiency. Muscle Nerve (Suppl 1), S129, 1994.
6.
Zierz S, Engel AG. Regulatory properties of a mutant carnitine palmitoyltransferase in human skeletal muscle. Eur J Biochem 149:207–214, 1985.
7.
Zierz S, Mundegar RR, Jerusalem F. Biochemical evidence for heterozygosity in muscular carnitine palmitoyltransferase deficiency. Clin Invest 72:77– 83, 1993.
8.
Bruno C, Bado M, Minetti C, Cordone G, DiMauro S. Novel mutation in the CPT II gene in a child with periodic febrile myalgia and myoglobinuria. J Child Neurol 15:390 –393, 2000.
9.
Martin MA, Rubio JC, De Bustos F, Del Hoyo P, Campos Y, Garcia A, Bornstein B, Cabello A, Arenas J. Molecular analysis in Spanish patients with muscle carnitine palmitoyltransferase deficiency. Muscle Nerve 22:941–943, 1999.
10.
Martin MA, Rubio JC, del Hoyo P, Garcia A, Bustos F, Campos Y, Cabello A, Culebras JM, Arenas J. Identification of novel mutations in Spanish patients with muscle carnitine palmitoyltransferase II deficiency. Hum Mutat 15:579 – 580, 2000.
11.
Taggart RT, Smail D, Apolito C, Vladutiu GD. Novel mutations associated with carnitine palmitoyltransferase II deficiency. Hum Mutat 13:210 –220, 1999.
12.
Yang BZ, Ding JH, Roe D, Dewese T, Day DW, Roe CR. A novel mutation identified in carnitine palmitoyltransferase II deficiency. Mol Genet Metab 63:110 –115, 1998.
NONSENSE MUTATION 515del4 13.
Elpeleg ON, Hammerman C, Saada A, Shaag A, Golzand E, Hochner-Celnikier D, Berger I, Nadjari M. Antenatal presentation of carnitine palmitoyltransferase II deficiency. Am J Med Genet 102:183–187, 2001. 14. Gieron MA, Korthals JK. Carnitine palmityltransferase deficiency with permanent weakness. Pediatr Neurol 3:51–53, 1987.
15.
185
Kieval RI, Sotrel A, Weinblatt ME. Chronic myopathy with a partial deficiency of the carnitine palmityltransferase enzyme. Arch Neurol 46:575–576, 1989. 16. Handig I, Dams E, Taroni F, Van Laere S, de Barsy T, Willems PJ. Inheritance of the S113L mutation within an inbred family with carnitine palmitoyltransferase enzyme deficiency. Hum Genet 97:291–293, 1996.
MUTATION REPORT A Novel Nonsense Mutation (515del4) in Muscle Carnitine Palmitoyltransferase II Deficiency Marcus Deschauer,* ,1 Thomas Wieser,* Rolf Schro¨der,† and Stephan Zierz* *Department of Neurology, Martin-Luther-Universita¨t Halle-Wittenberg, Ernst-Grube-Strasse 40, 06097 Halle/Saale, Germany; and †Department of Neurology, Rheinische Friedrich-Wilhelms-Universita¨t Bonn, Sigmund-Freud-Strasse 25, 53105 Bonn, Germany Received November 19, 2001, and in revised form November 26, 2001
in an autosomal recessive trait. The milder muscle form with infantile or adult onset is the most common disorder of lipid metabolism affecting skeletal muscle and the most frequent case of hereditary myoglobinuria. Attacks of exercise-induced muscle pain and weakness, rhabdomyolysis, and paroxysmal myoglobinuria eventually leading to renal failure are the prominent features of this disease. The severe multisystemic infantile form with onset during the first 2 years of life presents with attacks of liver failure with hypoketotic hypoglycemia, cardiomyopathy, or cardiac arrhythmias. Finally it is possible that the multisystemic infantile form manifests neonatally leading to death in the first month (1,2). The human CPT II gene is located at chromosome 1 and spans 20 kb containing 5 exons (3). In patients with the muscle form of CPT II deficiency a common S113L mutation was identified in about 60% of mutant alleles (4,5). Subsequently several rare disease causing mutations were communicated that can be associated with the muscle form of CPT II deficiency. We report on a new nonsense mutation in a patient with a severe course of the muscle form.
We identified a novel nonsense mutation in the carnitine palmitoyltransferase (CPT; EC 2.3.1.21) II gene in a patient with biochemical evidence of CPT II deficiency. The 39-year-old man suffered from the muscle form of CPT II deficiency. Attacks of myalgia and muscle weakness started in childhood and led to renal failure five times. A mild proximal weakness of the lower limbs was left as a residue. Molecular genetic analysis revealed the common S113L mutation on one allele. On the other allele a novel 4-bp deletion starting at codon 515 (515del4) was found leading to frameshift that results in a stop codon 15 codons upstream. Our data further expand the genetic heterogeneity in patients with CPT II deficiency. © 2002 Elsevier Science (USA) Key Words: carnitine palmitoyltransferase II; nonsense mutation.
The carnitine palmitoyltransferase (CPT) system (EC 2.3.1.21) is made up of two proteins, one located in the outer mitochondrial membrane (CPT I) and the other in the inner membrane (CPT II). They are important for the transport of long-chain fatty acids into the mitochondrial matrix. CPT II in contrast to CPT I exists only in one isoform across various tissues and CPT II deficiency presents as different phenotypes that are inherited
CASE REPORT
1 To whom correspondence should be addressed at Klinik und Poliklinik fu¨r Neurologie, Martin-Luther-Universita¨t Halle-Wittenberg, Ernst-Grube-Strasse 40, 06097 Halle/Saale, Germany. Fax: ⫹49 345 557 2020. E-mail: [email protected].
A 39-year-old man complained of attacks with myalgia and muscle weakness starting in childhood after he was sent to school. He had difficulties in sports in school because of muscle pain. Attacks 181 1096-7192/02 $35.00 © 2002 Elsevier Science (USA) All rights reserved.
182
DESCHAUER ET AL.
TABLE 1 Primers and PCR Conditions Primer
PCR conditions
Sense Exon Exon Exon Exon Exon Exon
I II III IVa IVb V
nt nt nt nt nt nt
39 to 63 ⫺65 to ⫺38 (intron 1) ⫺49 to ⫺27 (intron 2) ⫺47 to ⫺21 (intron 3) 1122 to 1144 ⫺56 to ⫺32 (intron 4)
Antisense nt nt nt nt nt nt
76 to 52 (intron 1) 46 to 23 (intron 2) 33 to 6 (intron 3) 1178 to 1152 73 to 48 (intron 4) 2115 to 2091
MgCl 2 1.0 1.5 1.5 1.5 1.5 1.5
Annealing
DMSO
54°C 60°C 58°C 60°C 60°C 60°C
3% — — — — —
mM mM mM mM mM mM
Note. Sequencing primers and amplification conditions for the entire coding region of the CPT II gene. Nucleotide positions for exonic primers according to cDNA sequence published by Finocchiaro et al. (3).
occurred after exercise, exposure to cold, infections, and fasting. Meanwhile he has problems after the slightest exercise. Up to now he had five severe episodes with myoglobinuria leading to acute renal failure and dialysis. None of his family members had similar symptoms. During the last episode with renal failure creatine phosphokinase was elevated to 35000 IU/L. One month later CK was normalized. Neurological examination at this moment revealed a moderate proximal paresis of the lower limbs. The patient had difficulty arising from a squat. Needle EMG of the deltoid and vastus lateralis muscle showed a myopathic pattern. Muscle biopsy showed histologically unspecific myopathic changes with atrophic fibers, increased variability in fiber size, perimysial fibrosis, and fat increase. There was little endomysial lymphatic and mononuclear cell infiltration. METHODS Biochemical Analysis of CPT in Muscle CPT activity in muscle homogenate was determined using the isotope forward assay under optimal conditions, and after preincubation with Triton X-100 (0.5%), and with the addition of malonyl-CoA (0.2 mM) (6,7). Molecular Genetic Studies Genomic DNA was extracted from muscle by standard methods. The common S113L mutation was identified by restriction fragment length polymorphism (RFLP) of polymerase chain reaction (PCR) products with the enzyme BstXI (4). For detection of
new mutations direct sequencing of PCR products was performed. For this purpose the coding region of the CPT II gene was amplified with six matching primer pairs (Table 1). Both strands of the PCR products were sequenced directly with the same primers used for amplification. Sequences were compared with the genomic structure of the CPT II gene according to Finocchiaro et al. (3). RFLP of a 699-bp PCR product containing the first part of exon 4 was performed with the enzyme StuI to confirm a new deletion in exon 4 and to exclude it in controls. Wild-type DNA was cut into fragments of 523 and 176 bp. In contrast deleted DNA was not cut. Fragments were visualized in a 2% agarose gel (Fig. 2). RESULTS Total CPT activity was normal (2.3 nmol ⫻ min ⫺1 ⫻ mg noncollagen protein). Residual activity after preincubation with Triton X-100 was 5% (normal 40.2 ⫾ 3.4%) and with addition of malonyl-CoA 5% (normal 56.7 ⫾ 6.4%). PCR-RFLP revealed that the patient was heterozygous for the S113L mutation. By direct sequencing a novel 4-bp deletion from position 1646 –1649 was observed in the heterozygous state in exon 4. This deletion starting at codon 515 (515del4) leads to a frameshift that results in a stop codon 15 codons upstream (Fig. 1). PCRRFLP confirmed that the patient was heterozygous for this mutation (Fig. 2). PCR-RFLP of the family members showed that the mother was heterozygous for the 515del4 mutation and the father was heterozygous for the S113L mutation. Two of
183
NONSENSE MUTATION 515del4
FIG. 1. Direct sequencing of PCR-amplified genomic DNA of exon 4 of CPT II gene. At codon 515 a 4-bp deletion is starting that deletes the third base of codon 515 (C) and all bases of codon 516 (TTT). The frameshift results in a stop codon 15 codons upstream.
the three asymptomatic brothers of the patient carried the S113L mutation on one allele. The third brother carried none of the mutant alleles
(Fig. 3). The mutation was not found in 110 alleles of 55 normal controls by PCR-RFLP. DISCUSSION Biochemically an abnormal regulation of CPT II was identified as it was shown previously in patients with the muscle form of CPT II deficiency (6,7). The identified 515del4 mutation is likely to be pathogenic for the following reasons: (1) the stop codon results in premature termination of protein translation after 529 amino acids, resulting in a truncated peptide missing 20% of the enzyme mole-
FIG. 2. A 2% agarose gel of a 699-bp PCR product containing the first part of exon 4 after restriction enzyme digestion with StuI. Wild-type DNA was cut into fragments of 523 and 176 bp whereas deleted DNA was not cut. Lane 1: marker. Lane 2: control. Lane 3: index patient.
FIG. 3. Pedigree of the family with genotypes below the symbols. Index patient with filled symbols. Family members with one mutant allele half-filled.
184
DESCHAUER ET AL.
cule; (2) analysis of the parents’ DNA proved that the 515del4 mutation and the S113L mutation are located on different alleles in the index patient; (3) the mutation was absent in 110 alleles of 55 normal controls. Our data further expand the genetic heterogeneity in patients with CPT II deficiency. Up to now 25 mutations in the CPT II gene were communicated (1,8 –11). Seventeen of them can be associated with the muscle form of CPT II deficiency. Bonnefont et al. (1) distinguished between “mild” CPT II mutations leading to the muscle form and “severe” mutations leading to the multisystemic form if they are found in homozygosity. Since CPT II deficiency is an autosomal recessive disorder the presence of a “mild” mutation (e.g., S113L mutation) on one allele and a “severe” mutation (e.g., Y628S mutation) on the other allele seems to result in the muscle form and not the multisystemic form. On the other hand, there is a R631C mutation that does not fit in this classification because it has been reported in the homozygous state with either the muscle form or the multisystemic form (1). Besides the 515del4 mutation three other nonsense mutations were described in patients with the muscle form of CPT II deficiency that result in severe protein truncation. An R124X mutation and a 36 –38insGC mutation were each found in one patient compound heterozygous with the S113L mutation (10,12). A 413delAG-F448L mutation was found in 9 patients compound heterozygous with the S113L mutation (11,13). Homozygosity of the 413delAG-F448L mutation, however, has been found in two sibs with severe multisystemic antenatal presentation (13). This is consistent with the 413delAG-F448L mutation being classified as a severe mutation. It seems to be likely that the 515del4 mutation and the three other nonsense mutations belong to the group of “severe” mutations because nonsense mutations lead to truncated proteins. Missense mutations can be either “mild” or “severe” depending on the functional importance of the exchanged residue. Within the muscle form of CPT II deficiency, frequency and severity of the attacks are variable (2). Our patient showed a rather severe course of the disease with a mild proximal weakness between the attacks. Usually there is no muscle weakness between the attacks (2) but there are also cases with mild proximal limb weakness between the attacks (14,15). Myopathic pattern in EMG and myopathic changes in muscle biopsy underline the incomplete recovery from the attacks in our patient. It must be
elucidated if there is a genotype-phenotype correlation within the muscle form of CPT II deficiency. Possibly patients with a severe mutation on one allele combined with a mild mutation might have earlier onset, more attacks, a lower threshold for developing attacks of myoglobinuria, and persistent weakness than patients who carry mild mutations on both alleles. On the other hand, intrafamilial variability of the disease was observed (16), suggesting that factors other than genotype (e.g., hormonal factors) can modify the clinical picture. REFERENCES 1.
Bonnefont JP, Demaugre F, Prip-Buus C, Saudubray JM, Brivet M, Abadi N, Thuillier L. Carnitine palmitoyltransferase deficiencies. Mol Genet Metab 68:424 – 440, 1999.
2.
Zierz S. Carnitine palmitoyltransferase deficiency. In Myology, 2d ed. (Engel AG, Franzini-Armstrong C, Eds.). New York: McGraw-Hill, pp 1577–1586, 1994.
3.
Finocchiaro G, Taroni F, Rocchi M, Martin AL, Colombo I, Tarelli GT, DiDonato S. cDNA cloning, sequence analysis, and chromosomal localisation of the gene for human carnitine palmitoyltransferase. Proc Natl Acad Sci USA 88:661– 665, 1991.
4.
Taroni F, Verderio E, Dworzak F, Willems PJ, Cavadini P, DiDonato S. Identification of a common mutation in the carnitine palmitoyltransferase II gene in familial recurrent myoglobinuria patients. Nature Genet 4:314 –319, 1993.
5.
Zierz S, Engel AG, Olek K. The Ser113Leu mutation in the carnitine palmitoyltransferase deficiency. Muscle Nerve (Suppl 1), S129, 1994.
6.
Zierz S, Engel AG. Regulatory properties of a mutant carnitine palmitoyltransferase in human skeletal muscle. Eur J Biochem 149:207–214, 1985.
7.
Zierz S, Mundegar RR, Jerusalem F. Biochemical evidence for heterozygosity in muscular carnitine palmitoyltransferase deficiency. Clin Invest 72:77– 83, 1993.
8.
Bruno C, Bado M, Minetti C, Cordone G, DiMauro S. Novel mutation in the CPT II gene in a child with periodic febrile myalgia and myoglobinuria. J Child Neurol 15:390 –393, 2000.
9.
Martin MA, Rubio JC, De Bustos F, Del Hoyo P, Campos Y, Garcia A, Bornstein B, Cabello A, Arenas J. Molecular analysis in Spanish patients with muscle carnitine palmitoyltransferase deficiency. Muscle Nerve 22:941–943, 1999.
10.
Martin MA, Rubio JC, del Hoyo P, Garcia A, Bustos F, Campos Y, Cabello A, Culebras JM, Arenas J. Identification of novel mutations in Spanish patients with muscle carnitine palmitoyltransferase II deficiency. Hum Mutat 15:579 – 580, 2000.
11.
Taggart RT, Smail D, Apolito C, Vladutiu GD. Novel mutations associated with carnitine palmitoyltransferase II deficiency. Hum Mutat 13:210 –220, 1999.
12.
Yang BZ, Ding JH, Roe D, Dewese T, Day DW, Roe CR. A novel mutation identified in carnitine palmitoyltransferase II deficiency. Mol Genet Metab 63:110 –115, 1998.
NONSENSE MUTATION 515del4 13.
Elpeleg ON, Hammerman C, Saada A, Shaag A, Golzand E, Hochner-Celnikier D, Berger I, Nadjari M. Antenatal presentation of carnitine palmitoyltransferase II deficiency. Am J Med Genet 102:183–187, 2001. 14. Gieron MA, Korthals JK. Carnitine palmityltransferase deficiency with permanent weakness. Pediatr Neurol 3:51–53, 1987.
15.
185
Kieval RI, Sotrel A, Weinblatt ME. Chronic myopathy with a partial deficiency of the carnitine palmityltransferase enzyme. Arch Neurol 46:575–576, 1989. 16. Handig I, Dams E, Taroni F, Van Laere S, de Barsy T, Willems PJ. Inheritance of the S113L mutation within an inbred family with carnitine palmitoyltransferase enzyme deficiency. Hum Genet 97:291–293, 1996.