Carmen Gaudiano

Muscle biopsy and in vitro contracture test in subjects with idiopathic HyperCKemia.

Background:Persistent high creatine kinase (CK) levels may reflect underlying subclinical myopathies. In most cases, pathogenesis is unknown and clinical management is unclear. Though clinically asymptomatic, these subjects are potentially susceptible to malignant hyperthermia. Methods:The authors analyzed 37 subjects with persistent elevation of CK without significant weakness or other neurologic symptoms. Neurologic examination was performed according to manual muscle testing. Muscle biopsy and the in vitro contracture test were performed in all subjects. Results:Twenty-three subjects (51.1%) were completely asymptomatic. The others had minor symptoms such as occasional cramps (11 subjects, 24.4%), fatigue (5 subjects, 11.1%), a combination of cramps and fatigue (5 subjects, 11.1%), and muscle pain (1 case, 2.2%). Muscle biopsy enabled precise diagnosis in 3 cases and was normal in 3 cases. The more frequent changes were variation in fiber size (31.1%), a combination of nuclear internalization and variation in fiber size (26.6%), nuclear internalization (6.6%), minor mitochondrial changes (4.4%), and neurogenic atrophy (4.4%). Immunocytochemical analysis was normal in all patients. In vitro contracture testing detected one malignant hyperthermia–susceptible and one malignant hyperthermia–equivocal subject. Conclusions:The evidence of malignant hyperthermia susceptibility by in vitro contracture test seems to be relatively infrequent among subjects with idiopathic hyperCKemia, but the incidence of true malignant hyperthermia in idiopathic hyperCKemia is unknown. Muscle biopsy should be considered a useful, though not very sensitive, diagnostic tool in idiopathic hyperCKemia, because it enables potentially treatable disorders, such as inflammatory myopathies, to be discovered. No uniform morphologic finding typical of idiopathic hyperCKemia or malignant hyperthermia susceptibility was identified by muscle biopsy.

A novel heteroplasmic tRNASer(UCN) mtDNA point mutation associated with progressive external ophthalmoplegia and hearing loss

Abstract We sequenced all mitochondrial tRNA genes from a patient with sporadic external ophthalmoplegia (PEO) and 5% COX-negative fibers in muscle biopsy, who had no detectable large mtDNA deletions. Direct sequencing showed a heteroplasmic mutation at nucleotide 7506 in the dihydrouridine stem of the tRNA Ser(UCN) gene. RFLP analysis confirmed that 30% of muscle and 20% of urinary epithelium mtDNA harbored the mutation, which was absent in other tissues of the proband as well as in mtDNA of his mother and 100 patients with various encephalomyopathies. Several point mutations on mitochondrial tRNA genes have been reported in PEO patients without large-scale rearrangements of mtDNA but no point mutations have hitherto been found in the gene coding for tRNA Ser(UCN) .

Peripheral neuropathy in late-onset Krabbe disease: report of three cases

Late-onset Krabbe disease may have variable misleading clinical manifestations and be a puzzling problem for physicians. We report clinical and peripheral nerve studies of three patients with adult-onset Krabbe disease. Two cases had a predominantly spastic paraparesis; in one case, the symptoms mimicked a cerebrovascular disorder. Predominantly, demyelinating neuropathy was observed in one case and axonal neuropathy in two cases. In all cases, no typical intracytoplasmic inclusions were found. These observations suggest that peripheral neuropathy in adult-onset Krabbe disease has variable clinical and pathological characteristics, different from those described in the classic form.

A second MNGIE patient without typical mitochondrial skeletal muscle involvement

Mitochondrial neurogastrointestinal encephalomyopathy (MNGIE) is an autosomal recessive disease caused by mutations in the gene encoding thymidine phosphorylase (TYMP). Clinically, MNGIE is characterized by gastrointestinal dysmotility, cachexia, ptosis, ophthalmoparesis, peripheral neuropathy and leukoencephalopathy. Most MNGIE patients have signs of mitochondrial dysfunction in skeletal muscle at morphological and enzyme level, as well as mitochondrial DNA depletion, multiple deletions and point mutations. A case without mitochondrial skeletal muscle involvement and with a TYMP splice-acceptor site mutation (c. 215–1 G>C) has been reported. Here, we describe an Italian patient with the same mutation and without mitochondrial skeletal muscle involvement, suggesting a possible genotype–phenotype correlation.

Chronic progressive external ophthalmoplegia: A new heteroplasmic tRNALeu(CUN) mutation of mitochondrial DNA

We sequenced all genes of mitochondrial tRNAs of a patient with chronic progressive external ophthalmoplegia with 5% ragged red fibres and 15% COX-negative fibres but without macrorearrangements of mitochondrial DNA (mtDNA). Direct sequencing showed a novel heteroplasmic G>A substitution in position 12316 of tRNA(Leu(CUN)) gene. This change destroys a highly conserved G-C base coupling in tRNA TpsiC branch. By RFLP analysis we could demonstrate different degrees of heteroplasmy in different patients tissues. This alteration, absent in a population of 110 patients with different encephalomyopathies, can be considered pathogenic: it is the tenth tRNA(Leu(CUN)) pathogenic mutation described up to date.

Leukoencephalopathy in 21-β hydroxylase deficiency: Report of a family

21-hydroxylase deficiency is the most common cause of congenital adrenal hyperplasia, an autosomal recessive disorder characterized by impaired synthesis of cortisol from cholesterol by the adrenal cortex. Subclinical involvement of brain white matter has been reported in subjects with congenital adrenal hyperplasia. Here we report a woman with a genetically assessed classic congenital adrenal hyperplasia and brain white matter abnormalities. Both the carrier parents also showed signs of leucoencephalopathy. Common causes of leukoencephalopathy were excluded by appropriate analyses. Our observation suggests that white matter anomalies may also be present in carriers of a mutation in the CYP21 gene. We therefore suggest performing CYP21 gene analysis in subjects with brain MRI evidence of white matter abnormalities that cannot otherwise be explained.

A case of ovarioleukodystrophy without eIF2B mutations

A new association of Vanishing White Matter (VWM) and premature ovarian failure (POF) was recently described as a sole entity called ovarioleukodystrophy. Seven out of eight patients reported by Fogli et al. had translation initiation factor (eIF2B) mutations, specific to the VWM. The only patient without mutations had a distinctive neurological presentation that included cognitive deterioration without motor signs and white matter abnormalities restricted to the frontal lobe. We describe here a case suggestive of ovarioleukodistrophy carrying no eIF2B mutations.

Motor-sensory neuropathy without minifascicles in a patient with 46XY gonadal dysgenesis

We report a 36-year-old patient with 46XY pure gonadal dysgenesis (GD), who manifested a syndrome of progressive motor-sensory neuropathy. Sural nerve biopsy showed severe axonal neuropathy. Since reported cases of chronic motor-sensory neuropathy and pure gonadal dysgenesis have been characterized by nerve biopsy evidence of minifascicle formation, we suggest that this clinical association may be a new type of hereditary motor-sensory neuropathy, not necessarily associated with minifascicle formation.

Inheritance of a novel RYR1 mutation in a family with myotonic dystrophy type 1

To the Editor: The presence of two genetically distinct myopathic disorders segregating in a family has rarely been reported. We report a 24-year-old woman, an only child of unrelated parents, whose mother was diagnosed with myotonic muscular dystrophy (DM1: 600 CTG repeat in the DM1 gene) (Fig. 1d) and died of conductive cardiac pathology at the age of 50 years. Developmental milestones were normal. She had difficulty climbing stairs and rising from sitting from the age of 10 years. Neurological examination at 22 years showed weakness of the pelvic girdle, moderate calf hypertrophy, hyperlordosis and joint hyperlaxity. Serum creatine kinase (CK) level was normal. Electrocardiogram and echocardiogram were normal. Electromyogram (EMG) showed widespread myopathic signs and the absence of myotonia. Muscle biopsy showed moderate variation in fiber size and 30% nuclear internalization (Fig. 1a). There was type I uniformity, with multiple small and welldelimited areas devoid of oxidative activity (Fig. 1b). Molecular investigation of the RYR1 gene (polymerase chain reaction (PCR)–denaturing high-performance liquid chromatography (DHPLC) screening of genomic sequence, followed by direct sequencing of PCR products with abnormal DHPLC profile) identified a new missense mutation in exon 101 (14537C.T), resulting in a A4846V substitution (Fig. 1c). The same mutation was present in the mother, in addition to the DM1 mutation already mentioned. No mutation in the DM1 gene was detected in the proband. The mother manifested weakness and gait problems from childhood. At age 32, she was not able to climb stairs, and by 45, she was confined to a wheelchair. An electrocardiogram showed atrioventricular blockade. From age 47, she needed nocturnal ventilation. At 48 years, neurological examination showed alopecia, bilateral ptosis, myotonic phenomenon elicitable in the hands and severe generalized weakness. Walking unaided was impossible. CK level was increased (607IU/l; normal value (NV) , 170). In the last period, she was respirator dependent. At 49 years, she died suddenly likely of a heart attack’. The maternal grandfather also died suddenly of heart attack at the age of 42 years. He was reported to have severe difficulty in walking. The new mutation detected in this family (A4846V) maps to the RYR1 C-terminus (exon 101), a region that forms the calcium channel pore of the protein and has been identified as a central core disease (CCD) mutation hotspot. This mutation is in fact quite close to the R4861H mutation, previously reported in CCD families (1, 2). The combination of RYR1 and DM1 gene mutations does not explain the severe phenotype of the mother and possibly of the maternal grandfather. Although heart rhythm and conduction anomalies are among the major clinical manifestations in the evolution of myotonic dystrophy, sudden death because of heart involvement is not a frequent event and is presumably correlated with a more severe phenotype and with greater numbers of repeats. On the other hand, cardiac arrhytmias are not a reported finding associated with RYR1 mutation, even in patients with a severe phenotype. Strong variability in clinical manifestations may be observed within families or among individuals carrying the same RYR1 gene mutation (1, 3, 4). Curiously, the high percentage of internal centralization observed in the proband could be indicative of DM1, but this finding is also typical of CCD. To our knowledge, no case of CCD and MD1 has been described before in the same subject. It is noteworthy that although RYR1 and DMPK genes map quite close on the same chromosome (in 19q13.1 and 19q13.2-q13.3, respectively), they segregate independently and the association must therefore be regarded as coincidental. This case emphasizes the need to screen for mutations in other genes in a family with a history of one-muscle disease but where