A novel mutation (R271X) in the myotubularin gene causes a severe miotubular myopathy

The mutation is a C to T transition at nucleotide 811 of the MTM1 gene (OMIM 310400) leading to premature termination of translation at codon 271 of the myotubularin protein (R271X).

[Congenital ataxias of genetic origin with structural anomalies of the cerebellum]

Congenital ataxia is not a rare condition for who is involved in the practice of pediatric neurology. After a brief description on the normal development of the cerebellum, we present an extensive review on the neurological disorders due to malformations or metabolic disorders associated with hypoplasia of the cerebellum and congenital ataxia.

Mutations of SURF-1 in Leigh disease associated with cytochrome c oxidase deficiency

Leigh disease associated with cytochrome c oxidase deficiency (LD[COX-]) is one of the most common disorders of the mitochondrial respiratory chain, in infancy and childhood. No mutations in any of the genes encoding the COX-protein subunits have been identified in LD(COX-) patients. Using complementation assays based on the fusion of LD(COX-) cell lines with several rodent/human rho0 hybrids, we demonstrated that the COX phenotype was rescued by the presence of a normal human chromosome 9. Linkage analysis restricted the disease locus to the subtelomeric region of chromosome 9q, within the 7-cM interval between markers D9S1847 and D9S1826. Candidate genes within this region include SURF-1, the yeast homologue (SHY-1) of which encodes a mitochondrial protein necessary for the maintenance of COX activity and respiration. Sequence analysis of SURF-1 revealed mutations in numerous DNA samples from LD(COX-) patients, indicating that this gene is responsible for the major complementation group in this important mitochondrial disorder.

X-linked adrenoleukodystrophy: first report of the Italian Study Group

In this paper we report Italian data on X-linked adrenoleukodystrophy (ALD) collected from 1985 to 1997. This disease appears to be the most common of the peroxisomal disorders and is associated with a functional defect of the peroxisomal very long chain fatty acid (VLCFA) oxidation. In Italy 117 cases have been recognized, but many cases may be unrecognized due to the heterogeneous clinical manifestations that vary from mild to very severe forms. To control the devastating course of this disease two therapeutic approaches are under evaluation: bone marrow transplantation (BMT) and dietary treatment based on a mixture of glyceroyl trioleate (GTO) and glyceroyl trierucate (GTE). Our experience of 68 subjects submitted to dietary treatment shows that almost all patients with signs of cerebral involvement at the beginning of treatment worsened or died, patients with the milder form, adrenomyeloneuropathy (AMN), remained stable, while 4 of the 15 presymptomatic subjects developed neurological signs of the disease. In recent years a more accurate selection of patients and donors for BMT has given favourable results, but some strict criteria should be respected.

Giant dystrophin deletion associated with congenital cataract and mild muscular dystrophy

We report a patient with a large intragenic dystrophin deletion of exons 17-51 inclusive associated with congenital cataract and mild Becker muscular dystrophy. The cataract was similar to the congenital cataract described in the mdx mouse. The loss of 68% of the rod domain including hinge 2 and 3 regions did not adversely affect the correct localization of the dystrophin and the association with the dystrophin-associated glycoprotein complex. This observation may have implications for minigenes suitable for gene therapy.

A novel insertion mutation (A169i) in the CLN1 gene is associated with infantile neuronal ceroid lipofuscinosis in an Italian patient

Infantile neuronal ceroid lipofuscinosis (INCL) is a progressive encephalopathy characterized by psychomotor deterioration, early visual loss, and an evanishing EEG. Mutations in the CLN1 gene encoding palmitoyl-protein thioesterase (ppt) have been reported in all Finnish INCL patients and in several non-Finnish North European patients. No cases have been contributed from the Mediterranean area thus far. We identified a single adenine insertion at nucleotide position 169 (A169i) in the CLN1 gene in a family in which the proband suffered from an INCL-like syndrome. The novel mutation was homozygous in blood from the proband, heterozygous in his healthy parents, and not found in control alleles. The mutation leads to an early stop codon resulting in an abnormal and truncated ppt protein. Our observations provide the first molecular characterization of an Italian INCL patient and expand the list of the known defects in INCL.

Fulminant Leigh syndrome and sudden unexpected death in a family with the T9176C mutation of the mitochondrial ATPase 6 gene

We report an Italian family in which the T-to-C point mutation at nucleotide 9176 of the mitochondrial adenosine triphosphate synthetase (mtATPase) 6 gene is associated with an early-onset fulminant form of Leigh syndrome and with sudden unexpected death in two siblings, respectively. Polymerase chain reaction single-strand conformation polymorphism (PCR-SSCP) analysis and direct sequencing revealed that the mutation was homoplasmic in mitochondrial DNA of the proband. The T9176C mutation changes a highly conserved leucine to a proline in subunit 6 of the mtATPase gene and is maternally inherited, but the maternal relatives are asymptomatic. This point mutation was initially described in two brothers with bilateral striatal necrosis, a milder variant of Leigh syndrome.

Familial spastic paraplegia, axonal sensory-motor polyneuropathy and bulbar amyotrophy with facial dysmorphia: new cases of Troyer-like syndrome

We studied two Libyan siblings, born to healthy consanguineous parents, who had suffered from a progressive neurological disorder, characterized by facial dysmorphia, ataxia, spastic paraplegia and an axonal sensory-motor polyneuropathy, since the age of 3 years. The clinical picture progressed slowly over a 6-year period to involve also bulbar and distal limb muscles. Interestingly, we found unusual tubulofilamentous inclusions in peripheral nerves and presynaptic buttons at the neuromuscular junctions. Describing the clinical picture of this presumably new disorder, we comment on the difference from similar conditions.

Abnormalities of somatosensory and motor evoked potentials in adrenomyeloneuropathy: comparison with magnetic resonance imaging and clinical findings

We studied 6 patients with adrenomyeloneuropathy (AMN) showing mild signs of central nervous system involvement. All patients underwent brain and spinal magnetic resonance imaging (MRI) and somatosensory (SEP) and motor (MEP) evoked potential study. Whereas SEPs and MEPs were abnormal in all patients, only 1 patient showed brain MRI abnormalities; spinal MRI showed hypotrophy without focal abnormalities in 4 of 6 patients. Median nerve SEPs, which were recorded with noncephalic reference montage, revealed delayed or absent scalp P14 far-field potential in all patients and abnormal spinal N13 in 2. Moreover, tibial nerve SEPs revealed abnormalities of the subcortical P30 response in all 4 patients in whom scalp-to-ear recording was employed. These findings strongly suggest that in the early stages of disease neurological dysfunction is localized in the spinal cord, where it is difficult to assess using MRI. However, SEPs and MEPs, which show a typical pattern of abnormality in these patients, could be useful in disclosing signs of long tract involvement and in monitoring treatment.

New familial mitochondrial encephalopathy with macrocephaly, cardiomyopathy, and complex I deficiency

Two siblings presented with a new phenotype consisting of fatal progressive macrocephaly and hypertrophic cardiomyopathy. Onset of symptoms started in both patients at the end of the first month of life with massive brain swelling causing macrocephaly and evolving to extensive brain destruction. Light microscopy of the lesions showed extensive small-vessel proliferation and gliosis. A distinct deficiency of complex I of mitochondrial respiratory chain was established in cultured fibroblasts, skeletal muscle, and heart muscle. Specific lack of complex I protein was demonstrated by two-dimensional gel electrophoresis.

Mutations in the MTM1 gene implicated in X-linked myotubular myopathy. ENMC International Consortium on Myotubular Myopathy. European Neuro-Muscular Center

X-linked recessive myotubular myopathy (XLMTM) is characterized by severe hypotonia and generalized muscle weakness, with impaired maturation of muscle fibres. The gene responsible, MTM1, was identified recently by positional cloning, and encodes a protein (myotubularin) with a tyrosine phosphatase domain (PTP). Myotubularin is highly conserved through evolution and defines a new family of putative tyrosine phosphatases in man. We report the identification of MTM1 mutations in 55 of 85 independent patients screened by single-strand conformation polymorphism for all the coding sequence. Large deletions were observed in only three patients. Five point mutations were found in multiple unrelated patients, accounting for 27% of the observed mutations. The possibility of detecting mutations and determining carrier status in a disease with a high proportion of sporadic cases is of importance for genetic counselling. More than half of XLMTM mutations are expected to inactivate the putative enzymatic activity of myotubularin, either by truncation or by missense mutations affecting the predicted PTP domain. Additional mutations are missenses clustered in two regions of the protein. Most of these affect amino acids conserved in the homologous yeast and Caenorhabditis elegans proteins, thus indicating the presence of other functional domains.

Neurophysiological abnormalities in adrenoleukodystrophy carriers. Evidence of different degrees of central nervous system involvement

We studied 19 women, heterozygous for adrenoleukodystrophy (ALD) in whom the carrier status was demonstrated by abnormally high plasma levels of very-long-chain fatty acids. Clinical examination revealed slight neurological signs in two patients. Clear-cut neurological deficits in three, and it was fully normal in the remaining 14. All subjects underwent motor evoked potential (MEP) and somatosensory evoked potential (SEP) studies. Seventeen out of 19 subjects underwent brain MRI which demonstrated various degrees of abnormality in one asymptomatic and five symptomatic subjects; SEPs and MEPs revealed CNS involvement in 12 and 8 out of the 19 subjects, respectively. Symptomatic patients showed severe neurophysiological abnormalities, whereas milder but unequivocal EP abnormalities were found in seven of the 14 patients with normal clinical examination. Our data thus suggest CNS involvement in the majority of the ALD carriers, evident also in preclinical stages and progressively severe. The possibility of assessing different degrees of neurological involvement could be relevant for therapeutical purposes. Moreover, neurophysiological studies could provide the only objective marker of functional nervous system involvement, e.g. in order to monitor the efficacy of treatment, and in clinically and radiologically silent cases.

Restrictive cardiomyopathy due to desmin accumulation in a family with evidence of autosomal dominant inheritance

OBJECTIVE

A familial case of restrictive cardiomyopathy due to desmin accumulation characterized by severe disturbances of cardiac conduction is described.

BACKGROUND

Desmin is an intermediate filament normally present in the myocardium, particularly in the Purkinje fibres, in the skeletal and in the smooth muscle.

METHODS

Resting electrocardiogram, 2-dimensional and Doppler echocardiogram, cardiac catheterization, electrophysiological study have been performed in all siblings. Informed consent for endomyocardial biopsy was obtained only in one patient.

RESULTS

The mother showed bilateral pes cavus and complained of episodes of vertigo at the age of 36 years. At that time she was submitted to electrophysiological study and to permanent pacing. After 15 years of good health conditions, she developed heart failure and underwent cardiac transplantation. A 21 year old son had a syncope; his ECG was similar to that of his mother; a permanent pacemaker was implanted and a diagnosis of restrictive cardiomyopathy with desmin accumulation was confirmed at histopathology study. Afterwards, another 24 year old sib had a syncope with head trauma: ECG showed right atrial enlargement, left bundle branch block. After electrophysiological study, he started antiarrhythmic therapy. This patient showed bilateral pes cavus.

CONCLUSIONS

The early manifestation of desmin accumulation may be intraventricular conduction disorders that can be often controlled by pacemaker implantation. Clinical symptoms of heart failure may be absent for a long period of time. Pedigree analysis is most consistent of autosomal dominant inheritance.

The inv dup(15) syndrome: a clinically recognizable syndrome with altered behavior, mental retardation, and epilepsy

The most common of the heterogeneous group of the extra structurally abnormal chromosomes (ESACs) is the inv dup(15), whose presence results in tetrasomy 15p and partial tetrasomy 15q. Inv dup(15), containing the Prader-Willi/Angelman syndrome (PWS/AS) region, are constantly associated with phenotypic abnormalities and mental retardation. We report on four additional patients with inv dup(15), whose behavioral pattern, and neurologic and physical findings further delineate the phenotype of this neurogenetic syndrome. We also provide FISH analyses on chromosomes of the observed ESACs and discuss the role of a number of genes located within the tetrasomic region.

Maternally inherited cardiomyopathy: a new phenotype associated with the A to G AT nt.3243 of mitochondrial DNA (MELAS mutation)

The A to G transition at nt.3243 of the tRNALeu(UUR) gene of mtDNA, commonly associated with MELAS, was detected in several members of a family affected by a maternally inherited form of hypertrophic cardiomyopathy. These findings suggest adding cardiomyopathy in the list of phenotypes associated with the 3243 mutation.

Homozygosity mapping of Hallervorden-Spatz syndrome to chromosome 20p12.3-p13

Hallervorden-Spatz syndrome (HSS) (OMIM #234200) is a rare, autosomal recessive neurode-generative disorder with brain iron accumulation as a prominent finding. Clinical features include extrapyramidal dysfunction, onset in childhood, and a relentlessly progressive course. Histologic study reveals massive iron deposits in the basal ganglia. Systemic and cerebrospinal fluid iron levels are normal, as are plasma levels of ferritin, transferrin and ceruloplasmin. Conversely, in disorders of systemic iron overload, such as haemochromatosis, brain iron is not increased, which suggests that fundamental differences exist between brain and systemic iron metabolism and transport. In normal brain, non-haem iron accumulates regionally and is highest in basal ganglia. Pathologic brain iron accumulation is seen in common disorders, including Parkinson's disease, Alzheimer's disease and Huntington disease. In order to gain insight into normal and abnormal brain iron transport, metabolism and function, our approach was to map the gene for HSS. A primary genome scan was performed using samples from a large, consanguineous family (HS1) (see Fig. 1). While this family was immensely powerful for mapping, the region demonstrating homozygosity in all affected members spans only 4 cM, requiring very close markers in order to detect linkage. The HSS gene maps to an interval flanked by D20S906 and D20S116 on chromosome 20p12.3-p13. Linkage was confirmed in nine additional families of diverse ethnic backgrounds.

Spinal muscular atrophies: recent insights and impact on molecular diagnosis

Spinal muscular atrophies (SMA) are a group of motor neuron diseases characterized by degeneration of anterior horn cells of the spinal cord and by muscular atrophy. Childhood-onset SMA is one of the most frequent autosomal recessive diseases and a leading cause of infant mortality. The underlying biochemical defect of SMA is unknown. Recently two genes have been isolated from the critical region at 5q13, the survival motor neuron (SMN) gene and the neuronal apoptosis inhibitor protein (NAIP) gene. Both genes are frequently deleted in SMA patients. NAIP is deleted in at least 45% of severely affected patients but less frequently in the milder forms. Homozygous deletions of exon 7 of SMN are found in approximately 95% of patients independently of clinical severity. A few point mutations and microdeletions in SMN have also been reported. This high frequency of deletions makes SMN analysis an important molecular diagnostic tool for childhood-onset SMA and greatly facilitates prenatal diagnosis. SMN analysis has also proven useful for the diagnosis of adult-onset SMA and variant forms. Although questions such as phenotype-genotype correlation must still be solved, the isolation of SMN and adjacent genes constitutes an important step towards the understanding of the molecular basis of the disease.

X-linked neurodegenerative syndrome with congenital ataxia, late-onset progressive myoclonic encephalopathy and selective macular degeneration, linked to Xp22.33-pter

Linkage analysis was performed in a previously described family segregating for an X-linked progressive neurological disorder [Bertini et al., 1992]. In three generations, the disease was inherited from the mothers in seven affected males (Fig. 1). Five had severe congenital hypotonia and died during the first year of life. Two other boys (maternal cousins) were found to have severe congenital ataxia, late-onset progressive myoclonic encephalopathy, and selective macular degeneration; brain CT-scan showed moderate cerebellar vermis hypoplasia. Linkage analysis was carried out in 12 informative relatives using 35 microsatellite markers (Généthon) evenly distributed on the X chromosome. A multipoint analysis showed a significant linkage (Z > 2) between the disease and three markers in the Xp22.33 region: DYS403 (Z = 2.37, theta = 0) which maps in the pseudoautosomal region, DXS7099 (Z = 2.45, theta = 0), and DXS7100 (Z = 2.48, theta = 0). Further linkage analysis with more telomeric markers will refine the location of this severe X-linked encephalopathy.

Hypoparathyroidism in mitochondrial trifunctional protein deficiency

Mitochondrial trifunctional protein deficiency, a recently identified disorder of fatty-acid oxidation, may show characteristic features such as peripheral neuropathy, pigmentary retinopathy, and acute fatty liver degeneration in pregnant women with an affected fetus. We describe a patient with trifunctional protein deficiency whose clinical picture consisted of severe calcium and phosphate abnormalities caused by hypoparathyroidism.

A gene for familial paroxysmal dyskinesia (FPD1) maps to chromosome 2q

Dyskinesias are hyperkinetic and involuntary movements that may result from any of a number of different genetic, infectious, and drug-induced causes. Some of the hereditary dyskinetic syndromes are characterized by paroxysmal onset of the abnormal movements. The classification of the familial paroxysmal dyskinesias (FPD) recognizes several distinct, although overlapping, phenotypes. Different forms of the disorder include attacks that are (1) induced by sudden movement (kinesiogenic); (2) spontaneous (non-kinesiogenic); and (3) induced by prolonged periods of exertion. Linkage analysis was pursued in a family segregating an autosomal dominant allele for non-kinesiogenic FPD. The disease allele was mapped to a locus on chromosome 2q31-36 (LOD score 4.64, theta = 0). Identification of distinct genetic loci for the paroxysmal dyskinesias will lead to a new genetic classification and to better understanding of these disorders.

High dose immunoglobulin IV treatment in adrenoleukodystrophy

X-linked adrenoleukodystrophy (ALD) is an inborn error of peroxisomal metabolism characterised by progressive demyelination of the central nervous system and by hypoadrenalism. The biochemical defect of ALD results in an impairment in degradation of very long chain fatty acids (VLCFA) with their accumulation in plasma and tissues. Many therapeutic approaches have been tried. Recently, a restricted diet and glycerol trioleate/erucic (GTOE) supplementation have shown normalisation of VLCFA plasma levels, although they are not effective in altering the clinical course of X-linked ALD. The preliminary results are presented of a twelve month trial of immunomodulation by intravenous high-dose immunoglobulins in six patients, mean (SD) age 10.48 (2.8) affected by X-linked ALD, on VLCFA restricted diet plus GTOE supplementation therapy. Six patients aged 9.30 (1.5) with similar clinical characteristics and on the same restricted VLCFA regime of GTO/GTE therapy were studied as the control group. After two months VLCFA levels fell to normal values and remained so for all patients throughout the study. These data show that immunoglobulins are not able to arrest the progression of the disease. The MRI and clinical symptoms deteriorated to the same extent in both groups.

Autosomal recessive hypermyelinating neuropathy

We studied three patients from two kinships, affected by early onset hereditary motor and sensory neuropathy with probable autosomal recessive inheritance (HMSN type III). Morphological studies of sural nerve biopsies revealed an abnormal myelin proliferation. Two adult patients with long-term follow up, lost ability to walk at 28 and 22 years and showed severe involvement of the cranial nerves. Our observations suggest that "hypermyelination neuropathy" with early onset is a progressive disease with poor long-term prognosis. In one kinship the occurrence of the disease in two sibs of both sexes but not in parents, is consistent with an autosomal recessive inheritance. Familial cases of hypermyelination neuropathy have not been described in previous reports. Morphological aspects of this condition are compared with other forms of hypermyelination neuropathy.

Bilateral, reversible, selective thalamic involvement demonstrated by brain MR and acute severe neurological dysfunction with favorable outcome

We report on two children who presented acute, severe, neurological dysfunction with bilateral, reversible, selective thalamic lesions demonstrated by brain MRI. In both children neurological symptoms appeared two weeks after a febrile respiratory illness. Clinical conditions worsened in a few days to a stuporous state and tetraplegia in one and to coma with decerebrate posturing in the other. Three weeks after the onset, both children improved and recovered within one month. During the acute phase, brain MRI showed in both children bilateral hyperintense areas on T2-weighted sequences limited to both thalamic regions. During the follow-up, repeated brain MRI showed complete disappearance of abnormalities in one patient and a small residual left thalamic lesion in the other. In both patients hematological routine exams were normal. Bacterial and viral studies of serum and CSF were negative. CSF findings showed elevated white blood cell count and protein levels, with no oligoclonal IgG bands. Urine and CSF organic acids by GC/MS and plasma as well as CSF amino acids were normal. We believe that the benign evolution of this disorder and CSF findings strongly suggest a postinfectious process of the central nervous system.

Reducing body myopathy and desmin storage in skeletal muscle: morphological and biochemical findings

We describe clinical, morphological and biochemical findings of a patient with reducing body myopathy (RBM). This 15-year-old patient was affected by severe limb-girdle progressive myopathy with asymmetric distribution. Muscle biopsy showed many fibers with cytoplasmic polymorphic masses, which stained dark purple with modified Gomori's trichrome, associated with proliferation of cytoplasmic bodies. Cytoplasmic polymorphic masses showed marked reducing activity with menadione-nitro blue tetrazolium reaction. Ultrastructurally, there was great amount of highly electron-dense tubular-filamentous structures of 16-17 nm in diameter. Immunohistochemistry showed that many fibers were positive for desmin. Sodium dodecyl sulfate-electrophoresis disclosed an increase in two bands of approximately 53 and 70 kDa, and Western blot demonstrated that the 53-kDa band was desmin. It was not possible to characterize the 70-kDa protein further.

A new syndrome with ethylmalonic aciduria and normal fatty acid oxidation in fibroblasts

We describe four Italian male infants with a novel clinical phenotype characterized by orthostatic acrocyanosis, relapsing petechiae, chronic diarrhea, progressive pyramidal signs, mental retardation, and brain magnetic resonance imaging abnormalities. The first symptoms appeared after the termination of breast-feeding and introduction of formula feeding. Marked persistent 2-ethylmalonic aciduria was associated with abnormal excretion of C4-C5(n-butyryl-, isobutyryl-, isovaleryl-, and 2-methylbutyryl-)acylglycines and acylcarnitines and with intermittent lactic acidosis. Short- and branched-chain plasma acylcarnitine levels were also elevated. 2-Ethylmalonic aciduria is generally regarded as being indicative of a defect in fatty acid oxidation. Extensive studies of cultured fibroblasts failed to reveal such a defect. The observation of intermittent urinary excretion of 2-ethylhydracrylic acid pointed to involvement of the isoleucine R pathway in ethylmalonate biosynthesis. This hypothesis was tentatively corroborated by the biochemical responses to an oral isoleucine challenge in two patients. However, fibroblast studies showed normal oxidation rates of (14C)isoleucine (ul), indicating that this is not a defect of isoleucine oxidation expressed in skin fibroblasts. In one of two patients tested, cytochrome c oxidase activity was partially reduced (45%) in cultured fibroblasts. This unique clinical and biochemical phenotype identifies a new metabolic encephalopathy of yet undetermined cause.

Cardiomyopathy may be the only clinical manifestation in female carriers of Duchenne muscular dystrophy

Cardiomyopathy was reported in a few Duchenne muscular dystrophy (DMD) carriers with clinical evidence of myopathy. We report two carriers with dilated cardiomyopathy, increased serum CK, and no symptoms of muscle weakness. In heart biopsies of both patients, dystrophin-the protein product of DMD locus--was absent in many fibers. Dilated cardiomyopathy may be the only manifestation of dystrophin gene mutation in carriers.

Myopathy and hypertrophic cardiomyopathy with selective lysis of thick filaments

We present a undescribed condition in a girl who died at 8 years of hypertrophic cardiomyopathy. Muscle and endomyocardial biopsies disclosed a selective loss of thick filaments ultrastructurally. In muscle biopsy histochemical abnormalities of myofibrillar AT-Pase were confined to type 1 fibres. Gel electrophoresis of muscle homogenate showed no qualitative abnormalities of slow and fast myosin heavy chains (MHC) and light chains, and the amount of the different myosin isozymes was in agreement with histochemical myofibrillar ATPase findings. The pathogenetic mechanisms have not been elucidated in this case but we suspect an abnormality of the beta-cardiac MHC gene, the only gene expressed in the heart and in type 1 skeletal muscle fibres.

Manifesting heterozygotes in McArdle's disease: clinical, morphological and biochemical studies in a family

We report a family with McArdle's disease with several affected individuals in two generations. This unusual pedigree for an autosomal recessive disease is explained by the existence of manifesting heterozygotes in the maternal line. The presence of symptoms in heterozygotes seems to be due to a decrease in myophosphorylase activity below a critical threshold, ranging between 30% and 45% of normal mean value. The occurrence of several manifesting heterozygotes in the maternal line only can be explained by compound heterozygosity of a defective allele and a pseudodeficient allele for myophosphorylase, or by a genetic factor which regulates the phenotypic expression of the gene.

Presymptomatic diagnosis of SMA III by genotype analysis

Linkage analysis and prenatal prediction in families segregating autosomal recessive spinal muscular atrophy (SMA) has become feasible since the assignment of the locus responsible for type I-III SMA to region 5q12-q13.3. We have performed a segregation study of SMA in Italian families using molecular probes and highly informative PCR-based polymorphic markers. In one family, a 7-year-old boy affected with type III SMA and an 8-year-old apparently healthy brother had identical haplotypes. These findings prompted us to reexamine the apparently unaffected child. His neurological exam was normal. However, the electromyography (EMG) showed a pattern consistent with chronic SMA. To our knowledge this is the first example of presymptomatic diagnosis of SMA based on genotype analysis.

Biopsy diagnosis of a case of adult onset orthochromatic leukodystrophy. Clinical and brain biopsy findings

We report the intra vitam histopathological findings on the brain of a female patient presenting an adult form of orthochromatic leukodystrophy. At 38 years of age the patient began to show progressive dementia and a pseudobulbar syndrome. The pedigree revealed an autosomal dominant pattern of inheritance. The CT scan showed a wide hypodensity of the anterior white matter. Biochemical investigations showed only a slight elevation of serum VLCFA and no alteration of urinary enzymatic activities. Cortical and subcortical biopsy specimens from the right frontal lobe showed: neuronal loss in the gray matter, accumulation of autofluorescent material within residual neurons and sudanophilic material within macrophages and astrocytes, sparing of axons. Electron microscopy showed lamination and fragmentation of the myelin and the presence of electrondense bodies and vesicular material into oligodendrocytes and astrocytes. We discuss the differential diagnosis of OLD forms with adult onset, namely between Löwenberg-Hill disease and the pure form of OLD with pigmented glial cells.

Fatal infantile liver failure associated with mitochondrial DNA depletion

A 3-month-old girl was admitted to the hospital because of hypotonia and frequent vomiting. She had severe metabolic acidosis and her liver function was abnormal. Hepatomegaly and rapidly progressive liver failure developed, and she died at 4 months of age. Two half-siblings from a different mother had died in infancy of an undiagnosed myopathy. The liver was fatty and hepatocytes were filled with large and small lipid droplets. Other tissues were morphologically normal. The respiratory chain enzymes containing subunits encoded by mitochondrial DNA were markedly decreased in liver, partially decreased in muscle, but normal in other tissues. Southern blot analysis showed 90% depletion of mitochondrial DNA in liver, 53% depletion in muscle, and normal amounts in other tissues. This is the second case of fatal infantile liver failure associated with mitochondrial DNA depletion. This pathogenetic mechanism should be considered in infants with multiple respiratory chain defects and variable tissue expression.

Epilepsia partialis continua and neuronal migration anomalies

Neuronal migration anomalies commonly cause seizures that are partial in type and generally refractory to medical treatment. Epilepsia partialis continua (EPC), an unusual form of epilepsy commonly related to acute damage of the cerebral cortex or to a chronic lesion, has never been described in a patient with neuronal migration anomalies. In 50 children with epilepsy due to neuronal migration anomalies, we observed two cases of EPC. These two children had unilateral neuronal migration abnormalities with partial seizures other than EPC and contralateral hemiparesis. Epilepsia partialis continua appeared two to three years after the onset of partial attacks and was accompanied by a worsening of the children's previous hemiparesis. Although a rare seizure manifestation in children with neuronal migration anomalies, when it does appear, EPC can aggravate the clinical neurological condition and should always be investigated for in these cases. Because its clinical appearance is often subtle, as in these two children, EPC may easily remain undiagnosed.

Peripheral neuropathy with giant axons and cardiomyopathy associated with desmin type intermediate filaments in skeletal muscle

A sporadic case (female, aged 14 years) is reported who was affected by myopathy, restrictive cardiomyopathy and sensory motor polyneuropathy. A muscle biopsy showed accumulation of osmiophilic granular and filamentous material on electron microscopy, which stained positively in immunofluorescence for desmin. Increased desmin phosphorylated isoforms have been demonstrated by one- and two-dimensional electrophoresis. Sural nerve biopsy showed a peripheral neuropathy with giant axons, filled with closely packed neurofilaments. Clinical and morphological aspects of this new disease entity are discussed with regards to the classical form of giant axonal neuropathy and to other conditions of peripheral neuropathy with giant axons.

Congenital X-linked ataxia, progressive myoclonic encephalopathy, macular degeneration and recurrent infections

We report on 2 boys (maternal cousins), with severe congenital ataxia with generalized hypotonia, psychomotor retardation and recurrent bronchopulmonary infections. Later, they developed myoclonic encephalopathy and macular degeneration. Serial brain imaging investigations showed a cyst of the septum pellucidum, persistence of the cavum vergae, corpus callosum and cerebellar vermis hypoplasia without cortical atrophy. In the maternal pedigree, 5 males had recurrent bronchopneumonia associated with severe congenital hypotonia and died during the first years of life. Neurophysiological studies, including nerve conduction velocities, brainstem auditory evoked responses, somatosensory evoked potentials were normal. Electroretinogram showed normal wave morphology. Visual evoked potentials were mildly impaired. Extensive screening for metabolic disease gave normal results. Immunologic investigations showed normal T and B cell number, T cell function and immunoglobulin levels in both patients with a reduced level of IgG2 subclass in one.

Giant axonal neuropathy: report on a case with focal fiber loss

We report on a 5 1/2 year-old boy with chronic progressive polyneuropathy, ataxia, and pyramidal signs. His hair was not curled. Sural nerve biopsy disclosed many axons enlarged by accumulation of 10-nm neurofilaments and a marked variability in the number of myelinated fibers as well as in the amount of axonal enlargements among different fascicles. These findings and the electrophysiological data were consistent with a giant axonal polyneuropathy with a multifocal fiber loss.

Peripheral sensory-motor polyneuropathy, pigmentary retinopathy, and fatal cardiomyopathy in long-chain 3-hydroxy-acyl-CoA dehydrogenase deficiency

An 11-month-old girl presented acute episodes of hypoglycaemia and hepatic encephalopathy reminiscent of Reye syndrome and 3-hydroxydicarboxylic aciduria. The patient showed peculiar clinical manifestations of severe sensory-motor neuropathy, pigmentary retinopathy, and cardiomyopathy. She died of cardiac failure. Pathological studies of peripheral nerve showed signs of axonal neuropathy and demyelination. Enzymatic studies in cultured fibroblasts showed a deficiency of mitochondrial long-chain 3-hydroxyacyl-CoA-dehydrogenase. Peripheral nerve involvement and retinal pigmentary degeneration have as yet not been described in patients with proven defects of mitochondrial beta-oxidation.

Bilateral striatal necrosis, dystonia and optic atrophy in two siblings

Two siblings developed a neurological disorder in the first decade characterised by generalised dystonia, hypokinesia, and subacute visual loss. CT and serial MRI examinations showed bilateral lesions of the striatum, mainly in the putamen. The classification of these patients is discussed in relation to infantile bilateral striatal necrosis (IBSN), Leigh's disease, and Leber's optic neuropathy. The literature shows a clinical and aetiopathogenetic overlap between these syndromes. In our cases parental consanguinity and the involvement of a single generation suggest a new clinical condition with autosomal recessive transmission.

Dominantly inherited mitochondrial myopathy with multiple deletions of mitochondrial DNA: clinical, morphologic, and biochemical studies

We studied a large family with a dominantly inherited mitochondrial myopathy characterized by progressive external ophthalmoplegia, dysphagia, cataract, lactic acidosis, exercise intolerance, and early death. Morphologic studies of muscle biopsies suggested mitochondrial heteroplasmy and revealed ragged-red fibers and decreased histochemical reactions for cytochrome c oxidase and succinate dehydrogenase. Biochemistry showed a partial defect of cytochrome c oxidase and a mild generalized reduction of other mitochondrial enzymes requiring mitochondrial DNA-encoded subunits. Southern blot analysis and PCR amplification showed mitochondrial DNA deletions in muscle of all affected members, but not in lymphocytes or fibroblasts, suggesting a tissue-specific distribution. Deletions were multiple and seemed to increase with time and to correlate with the severity of the disease.

Neuromyopathy and restrictive cardiomyopathy with accumulation of intermediate filaments: a clinical, morphological and biochemical study

The clinical, morphological and biochemical findings of a sporadic case, showing accumulation of desmin-type intermediate filaments in skeletal muscle and myocardium are described. Desmin storage was demonstrated by immunofluorescence, sodium dodecyl sulfate gel electrophoresis and two-dimensional gel electrophoresis. These findings are in agreement with those of Rappaport et al. (FEBS lett. 231:421-425, 1989). A sensory-motor polyneuropathy was established by electrophysiological studies and, ultrastructurally, intramuscular nerves showed accumulation of neurofilaments and neurotubules with formation of axonal spheroids. These findings are discussed considering all previous reports with related conditions.