Prenatal diagnosis of lysosomal storage diseases

The prenatal diagnosis of lysosomal storage disorders can be achieved, once the diagnosis is confirmed in the index case, by a variety of techniques including analysis of amniotic fluid, asay of enzymic activity in cultured amniotic fluid cells, cultured chorionic villus cells and by direct assay of activity in chorionic villus samples. These studies can be accompanied by ultrastructural observations which give an independent means of diagnosis. In some instances molecular genetic studies for mutation detection or linkage analysis are appropriate for prenatal diagnosis. Pseudodeficiencies of some of the lysosomal enzymes, which cause no clinical problems, can complicate the initial diagnosis particularly in metachromatic leucodystrophy where the pseudodeficiency is more common than the disease itself. Mutation analysis as well as enzyme assay is necessary not only in the index case but also in the parents before the same techniques are applied to a sample for prenatal diagnosis. A large number of lysosomal storage disorders may present as fetal hydrops and the diagnosis can be established at this late stage by fetal blood sampling and examination by microscopy as well as by biochemical assay of the appropriate enzyme or metabolite in amniotic fluid. All prenatal diagnoses in which an affected fetus is indicated should have confirmation of the diagnosis as soon as possible to reassure anxious parents, and to act as audit of the laboratory's competence to undertake prenatal diagnosis. A combined approach to prenatal diagnosis involving biochemical, molecular genetic and morphological studies is recommended.

Exclusion of late infantile neuronal ceroid lipofuscinosis (LINCL) in a fetus by assay of tripeptidyl peptidase I in chorionic villi

We report the exclusion of late infantile neuronal ceroid lipofuscinosis in a fetus by assay of tripeptidyl peptidase I activity and by mutational analysis in chorionic villi. This is the first pregnancy at risk for LINCL to be monitored by enzyme assay. No morphological abnormalities were detected.

Cytochrome oxidase immunohistochemistry: clues for genetic mechanisms

Cytochrome c oxidase (COX) is encoded by three mitochondrial and nine nuclear genes. COX deficiency is genetically heterogeneous but current diagnostic methods cannot easily distinguish between mitochondrial and nuclear defects. We hypothesized that there may be differential expression of COX subunits depending on the underlying mutation. COX subunit expression was investigated in five patients with known mtDNA mutations. Severe and selective reduction of mtDNA-encoded COX subunits I and II was consistently observed in all these patients and was restricted to COX-deficient fibres. Immunostaining of nuclear-encoded subunits COX IV and Va was normal, whilst subunit VIc, also nuclear-encoded, was decreased. Twelve of 36 additional patients with histochemically defined COX deficiency also had this pattern of staining, suggesting that they had mtDNA defects. Clinical features in this group were heterogeneous, including infantile encephalopathy, multisystem disease, cardiomyopathy and childhood-onset isolated myopathy. The remaining patients did not have the same pattern of immunostaining. Fourteen had reduced staining of all subunits, whilst 10 had normal staining of all subunits despite reduced enzyme activity. Patients with COX deficiency secondary to mtDNA mutations have a specific pattern of subunit loss, but the majority of children with COX deficiency do not have this pattern of subunit loss and are likely to have nuclear gene defects.

Lymphocyte inclusions in Finnish-variant late infantile neuronal ceroid lipofuscinosis (CLN5)

Electron microscopic reinvestigation of archival samples of peripheral blood lymphocytes of four patients with Finnish-variant late infantile neuronal ceroid lipofuscinosis (CLN5) showed inclusions with dark globules and particles showing fingerprint profiles. Findings, in contrast to an earlier report, show that the lymphocytes in this disease carry pathognomonic cytosomes like all other forms of neuronal ceroid lipofuscinosis in childhood.

A missense mutation of cytochrome oxidase subunit II causes defective assembly and myopathy

We report the first missense mutation in the mtDNA gene for subunit II of cytochrome c oxidase (COX). The mutation was identified in a 14-year-old boy with a proximal myopathy and lactic acidosis. Muscle histochemistry and mitochondrial respiratory-chain enzymology demonstrated a marked reduction in COX activity. Immunohistochemistry and immunoblot analyses with COX subunit-specific monoclonal antibodies showed a pattern suggestive of a primary mtDNA defect, most likely involving CO II, for COX subunit II (COX II). mtDNA-sequence analysis demonstrated a novel heteroplasmic T-->A transversion at nucleotide position 7,671 in CO II. This mutation changes a methionine to a lysine residue in the middle of the first N-terminal membrane-spanning region of COX II. The immunoblot studies demonstrated a severe reduction in cross-reactivity, not only for COX II but also for the mtDNA-encoded subunit COX III and for nuclear-encoded subunits Vb, VIa, VIb, and VIc. Steady-state levels of the mtDNA-encoded subunit COX I showed a mild reduction, but spectrophotometric analysis revealed a dramatic decrease in COX I-associated heme a3 levels. These observations suggest that, in the COX protein, a structural association of COX II with COX I is necessary to stabilize the binding of heme a3 to COX I.

Targeted disruption of the Cln3 gene provides a mouse model for Batten disease. The Batten Mouse Model Consortium [corrected]

Batten disease, a degenerative neurological disorder with juvenile onset, is the most common form of the neuronal ceroid lipofuscinoses. Mutations in the CLN3 gene cause Batten disease. To facilitate studies of Batten disease pathogenesis and treatment, a murine model was created by targeted disruption of the Cln3 gene. Mice homozygous for the disrupted Cln3 allele had a neuronal storage disorder resembling that seen in Batten disease patients: there was widespread and progressive intracellular accumulation of autofluorescent material that by EM displayed a multilamellar rectilinear/fingerprint appearance. Inclusions contained subunit c of mitochondrial ATP synthase. Mutant animals also showed neuropathological abnormalities with loss of certain cortical interneurons and hypertrophy of many interneuron populations in the hippocampus. Finally, as is true in Batten disease patients, there was increased activity in the brain of the lysosomal protease Cln2/TPP-1. Our findings are evidence that the Cln3-deficient mouse provides a valuable model for studying Batten disease.

Ultrastructural and electrophysiological correlation of the genotypes of NCL

Several genetically different, but clinically similar childhood forms of neuronal ceroid lipofuscinosis are now recognized. Accurate diagnosis is important so that appropriate genetic advice can be given, molecular analysis can be undertaken, and prenatal testing can be considered. A combined clinical, electrophysiological, and histological (light and electron microscopy) approach offers the most reliable means of diagnosis in the majority of patients. Patients with an unusual presentation will also be identified.

A new locus for variant late infantile neuronal ceroid lipofuscinosis-CLN7

To date two genes are known to be involved in variant LINCL, CLN5 and CLN6, which map to chromosomes 13q21 and 15q21-23. A subset of Turkish families with a variant phenotype has been identified. Affected individuals have curvilinear bodies and fingerprint profiles on EM but are recombinant at CLN5 and CLN6. These families appear to represent a new locus. Homozygosity mapping is being used to map this locus, which has been designated CLN7.

A murine model for juvenile NCL: gene targeting of mouse Cln3

JNCL is a neurodegenerative disease of childhood caused by mutations in the CLN3 gene. A mouse model for JNCL was created by disrupting exons 1-6 of Cln3, resulting in a null allele. Cln3 null mice appear clinically normal at 5 months of age; however, like JNCL patients, they exhibit intracellular accumulation of autofluorescent material. A second approach will generate mice in which exons 7 and 8 of Cln3 are deleted, mimicking the common mutation in JNCL patients.

Genetic and physical mapping of the CLN6 gene on chromosome 15q21-23

CLN6, the gene for a variant late infantile neuronal ceroid lipofuscinosis, has been mapped to chromosome 15q21-23 by homozygosity mapping. At present the family resource consists of 31 families. By the analysis of additional polymorphic markers in this resource the critical region has been narrowed down from 12 cM to less than 4 cM. A physical map is being constructed using YAC and PAC clones as a prerequisite to transcript mapping.

Skin fragility and hypohidrotic ectodermal dysplasia resulting from ablation of plakophilin 1

We report a 2-year-old boy with an unusual autosomal recessively inherited skin disease comprising trauma-induced skin fragility and congenital ectodermal dysplasia affecting hair, nails and sweat glands. Skin biopsy showed widening of intercellular spaces between keratinocytes and ultrastructural findings of small, poorly formed desmosomes with reduced connections to the keratin filament cytoskeleton. Immunohistochemical analysis revealed a complete absence of staining for the accessory desmosomal plaque protein plakophilin 1 (PKP1; band 6 protein). The affected individual was a compound heterozygote for null mutations on both alleles of the PKP1 gene. Both mutations occurred within the amino terminus of PKP1, the domain which normally binds the cytoskeletal keratin filament network to the cell membrane. Apart from its localization within desmosomal plaques, PKP1 may also be present within the cytoplasm and nucleus and has putative roles in signal transduction and regulation of gene activity. The clinicopathological observations in this patient demonstrate the relevance of PKP1 to desmosome formation, cutaneous cell-cell adhesion and epidermal development and demonstrate the specific manifestations of human functional knockout mutations in this gene.

Pyloric atresia-junctional epidermolysis bullosa syndrome: mutations in the integrin beta4 gene (ITGB4) in two unrelated patients with mild disease

Junctional epidermolysis bullosa associated with pyloric atresia (EB-PA; OMIM 226730) is a rare autosomal recessively inherited disease in which mucocutaneous fragility is associated with gastrointestinal atresia. This disease is usually fatal within the first few weeks or months of life even following surgical correction of the intestinal obstruction. Recently, mutations in the genes encoding the epithelial integrin alpha6beta4 (ITGA6 and ITGB4) have been identified in several patients with EB-PA. We report two unrelated patients with this disease who have survived into early childhood with mild cutaneous involvement, in whom we have identified pathogenetic mutations in ITGB4. The first patient was a compound heterozygote for a splice site mutation in exon 30 (3793 + 1G-to-A) and a non-sense mutation in exon 36 (W1478X), and the second was a compound heterozygote for a missense mutation in exon 3 (C38R) and a 1 bp deletion in exon 36 (4776delG). Although the non-sense and deletion mutations are predicted to result in markedly reduced beta4 integrin mRNA levels, the presence of the missense or splice site mutation on the second allele may enable the synthesis of some functional, albeit perturbed, beta4 polypeptide. Determination of the molecular mechanisms in these two cases increases our understanding of EB-PA and may enable correlation between genotype and phenotype.

Hepatic mitochondrial 3-hydroxy-3-methylglutaryl-coenzyme a synthase deficiency

There are at least two isoenzymes of 3-hydroxy-3-methylglutaryl (HMG)-CoA synthase (EC 4.1.3.5) located in the mitochondrial matrix and the cytoplasm of hepatocytes, respectively. The mitochondrial enzyme is necessary for the synthesis of ketone bodies, which are important fuels during fasting. We report a child with a deficiency of this isoenzyme. He presented at 16 mo with hypoglycemia. There was no rise in ketone bodies during fasting or after a long chain fat load but there was a small rise after a leucine load. Measurement of beta-oxidation flux in fibroblasts was normal. Using antibodies specific for mitochondrial HMG-CoA synthase, no immunoreactive material could be detected on Western blotting. Total HMG-CoA synthase activity in liver homogenate was only slightly lower than in control samples. Presumably, as there was no mitochondrial HMG-CoA synthase enzyme protein, this activity arose from the cytoplasmic or other (e.g. peroxisomal) isoenzymes. With avoidance of fasting, our patient has had no problems since presentation and is developing normally at 4 y of age.

E210K mutation in the gene encoding the beta3 chain of laminin-5 (LAMB3) is predictive of a phenotype of generalized atrophic benign epidermolysis bullosa

Pathogenetic mutations in the genes encoding the hemidesmosome-anchoring filament complex proteins, laminin-5 and the 180 kDa bullous pemphigoid antigen, have been identified in patients with the inherited mechanobullous disease, junctional epidermolysis bullosa (EB). Furthermore, there is some evidence to suggest that precise definition of the nature of mutations in these genes may correlate to specific phenotypes of disease. We report three junctional EB patients who carry an identical missense mutation, E210K, on one allele of the gene encoding the beta3 subunit chain of laminin-5 (LAMB3) in addition to different nonsense mutations on the second allele. Two of the patients are adults and display a specific phenotype of non-lethal junctional EB known as generalized atrophic benign EB, which is associated with trauma-induced blisters, nail dystrophy and alopecia. As the third patient is a young child with fewer features of this subtype to date, identification of E210K in combination with a nonsense LAMB3 mutation may be predictive of the subsequent development of a generalized atrophic benign EB phenotype both in this child and in other junctional EB patients with the E210K mutation. Identification of this particular mutation has important implications for clinical management and counselling.

Liver failure associated with mitochondrial DNA depletion

BACKGROUND/AIMS

Liver failure in infancy can result from several disorders of the mitochondrial respiratory chain. In some patients, levels of mitochondrial DNA are markedly reduced, a phenomenon referred to as mitochondrial DNA depletion. To facilitate diagnosis of this condition, we have reviewed the clinical and pathological features in five patients with mitochondrial DNA depletion.

METHODS

Cases were identified by preparing Southern blots of DNA from muscle and liver, hybridising with appropriate probes and quantifying mitochondrial DNA relative to nuclear DNA.

RESULTS

All our patients with mitochondrial DNA depletion died of liver failure. Other problems included hypotonia, hypoglycaemia, neurological abnormalities (including Leigh syndrome) and cataracts. Liver histology showed geographic areas of fatty change, bile duct proliferation, collapse of liver architecture and fibrosis; some cells showed decreased cytochrome oxidase activity. Muscle from three patients showed mitochondrial proliferation, with loss of cytochrome oxidase activity in some fibres but not in others; in these cases, muscle mitochondrial DNA levels were less than 5% of the median control value. The remaining two patients (from a single pedigree) had normal muscle histology and histochemistry associated with less severe depletion of mitochondrial DNA in muscle.

CONCLUSIONS

Liver failure is common in patients with mitochondrial DNA depletion. Associated clinical features often include neuromuscular disease. Liver and muscle histology can be helpful in making the diagnosis. Mitochondrial DNA levels should be measured whenever liver failure is thought to have resulted from respiratory chain disease.

Mutations in the palmitoyl-protein thioesterase gene (PPT; CLN1) causing juvenile neuronal ceroid lipofuscinosis with granular osmiophilic deposits

A subtype of neuronal ceroid lipofuscinosis (NCL) is well recognized which has a clinical course consistent with juvenile NCL (JNCL) but the ultrastructural characteristics of infantile NCL (INCL): granular osmiophilic deposits (GROD). Evidence supporting linkage of this phenotype, designated vJNCL/GROD, to the INCL region of chromosome 1p32 was demonstrated (pairwise lod score with D1S211 , Z max = 2.63, straight theta = 0.00). The INCL gene, palmitoyl-protein thioesterase (PPT ; CLN1), was therefore screened for mutations in 11 vJNCL/GROD families. Five mutations in the PPT gene were identified: three missense mutations, Thr75Pro, Asp79Gly, Leu219Gln, and two nonsense mutations, Leu10STOP and Arg151STOP. The missense mutation Thr75Pro accounted for nine of the 22 disease chromosomes analysed and the nonsense mutation Arg151STOP for seven. Nine out of 11 patients were shown to combine a missense mutation on one disease chromosome with a nonsense mutation on the other. Mutations previously identified in INCL were not observed in vJNCL/GROD families. Thioesterase activity in peripheral blood lymphoblast cells was found to be markedly reduced in vJNCL/GROD patients compared with controls. These results demonstrate that this subtype of JNCL is allelic to INCL and further emphasize the correlation which exists between genetic basis and ultrastructural changes in the NCLs.

Loci for classical and a variant late infantile neuronal ceroid lipofuscinosis map to chromosomes 11p15 and 15q21-23

The childhood neuronal ceroid lipofuscinoses (NCLs) are a group of autosomal recessive neurodegenerative disorders characterised by progressive visual failure, neurodegeneration, epilepsy and the accumulation of an autofluorescent lipopigment in neurones and other cells. Three main subtypes have been identified according to age of onset, clinical features and ultrastructural morphology. These are infantile NCL (INCL; CLN1), classical late infantile NCL (LINCL; CLN2) and juvenile NCL (JNCL; CLN3). Several atypical forms of late infantile NCL (LINCL) have also been described including a Finnish variant LINCL (CLN5). The CLN2 gene has been excluded from the CLN1, CLN3 and CLN5 loci. A genome search was initiated using a homozygosity mapping strategy in five classical LINCL and two variant LINCL consanguineous families. A common region of homozygosity was identified on chromosome 11p15 in two of the classical families. Analysis of a further 33 classical LINCL families supported linkage in this region (Zmax = 3.07 at theta = 0.06 at D11S1338). A common region of homozygosity was also observed on chromosome 15q21-23 in the two variant LINCL families. Extension of the analysis to include a further seven families of identical ultrastructural phenotype established linkage to this region (Zmax = 6.00 at theta = 0.00 at D15S1020).

Salla disease--rare or underdiagnosed?

Salla disease is described in two English children. Eighty-seven of the 89 cases so far reported come from Finland. It may be genuinely rare outside Finland or possibly underdiagnosed. Although a lysosomal disorder, it lacks many of their more characteristic features. Deterioration, for example, in the paediatric age range is rare. The clinical features are, however, consistent and specific. Definitive diagnosis is achieved by demonstrating increased amounts of free sialic acid in cultured skin fibroblasts. If the colorimetric method in widespread use is employed for this, a false negative result may be obtained. High-pressure liquid chromatography is sufficiently sensitive. It is possible therefore that Salla disease is under-reported, both from lack of clinical awareness and from lack of appropriate laboratory confirmation.

Congenital muscular dystrophy with severe retrocollis and mental retardation: a report of two siblings

Two siblings with a congenital muscular dystrophy and severe mental retardation which was not due to dystrophin, merosin, or adhalin deficiency are described. These cases overlap with congenital muscular dystrophy of the Fukuyama-type but are less severe. Atypical features include limited facial involvement, retained ambulation, and severe retrocollis.

Light and electron microscopic studies on subunit c in cultured fibroblasts in late infantile and juvenile Batten disease

Immunohistochemical and ultrastructural studies were undertaken to determine whether accumulation of subunit c of mitochondrial ATP synthase could be detected microscopically in fibroblasts cultured from patients with late infantile and with juvenile Batten disease. Cells were grown for five weeks with and without colchicine to inhibit cell division, and were studied grown on slides, as cytospin preparations or as centrifuged pellets. The two different immunohistochemical detection methods used (peroxidase/DAB and immunogoldsilver) gave different results, but neither method indicated any accumulation of subunit c. There was no ultrastructural or electronhistochemical evidence of storage. The published biochemical results which give apparently conflicting evidence of excess amounts of subunit c in cultured fibroblasts can be explained by quantitative differences and sensitivity of the detection methods.

Bone marrow transplantation in late infantile Batten disease and juvenile Batten disease

Two patients, one each with LINCL and JNCL, underwent BMT in an attempt to alter the course of their disease. The LINCL patient received two transplants, one when asymptomatic, which was rapidly rejected, and a second BMT at age 3 years 9 months when the EEG had become abnormal. He has deteriorated in the following 2 years and now has only a few words, limited vision and feeding difficulties. Only two major seizures have occurred, but minor seizures are frequent. Although he is less severely affected than his sister at the same age, it is difficult to know if BMT has had any effect. The most significant difference is the relative mildness of seizure activity. The JNCL patient, transplanted at 8 years, when her visual problems had already started, is still in mainstream school, has good speech and good quality of life at age 9 1/2 years. No regression has been found, but EEG changes are now present and her vision has further deteriorated. The effect of BMT, if any, will not become apparent for several years in the more slowly progressive JNCL.

A form of juvenile Batten disease with granular osmiophilic deposits

The clinical, neurophysiological and pathological features of a patient who presented with the clinical features of juvenile Batten disease, yet who had storage of granular osmiophilic deposits (GROD) on ultrastructural examination of biopsy and postmortem tissues is described. The ultrastructural features are those usually found in the infantile form of Batten disease. The postmortem study showed marked neuronal storage of a lipofuscin-like material in an atrophic brain without loss of myelin. The cerebellum showed almost complete loss of Purkinje cells and loss of the granule cells. No accumulation of subunit c of mitochondrial ATP synthase was found. The clinical and neurophysiological findings are compared with those of the classical juvenile form and with those of the few reported cases of juvenile Batten disease with GROD. The importance of correct classification of patients with Batten disease and its impact on the molecular genetic studies is emphasised. The pathogenesis of this form of the disease is considered to be similar to that for infantile Batten disease.

Deficiency of respiratory chain complex I is a common cause of Leigh disease

We reviewed the clinical features and etiologies of Leigh disease in 66 patients from 60 pedigrees. Biochemical or molecular defects were identified in 50% of all pedigrees, and in 74% of the 19 pedigrees with pathologically proved Leigh disease. Isolated deficiency of respiratory chain complex I was found in 7 patients, though the complex was only assayed in 25 patients, making this the second most common biochemical abnormality after complex IV deficiency. Mutations at residue 8993 of mitochondrial DNA were found in only 2 patients. No correlation was found between the clinical features and etiologies. No defects were identified in the 8 patients with normal lactate concentrations in the cerebrospinal fluid.

Inherited ichthyoses: a review of the histology of the skin

The histology of skin biopsies from 46 cases of different forms of congenital ichthyosis was reviewed. Sections were examined for hyperkeratosis, follicular keratosis, appearance of the granular layer, epidermal thickness, tonofilament clumps, epidermal vacuolation, spongiosis, bullae and dyskeratosis, appearance of the basal layer, inflammation, mitoses, and adnexae. A detailed description of the histological features of each type of ichtnyosis studied is presented. Some ichthyoses can be recognized on routine hematoxylin and eosin staining (bullous ichthyosiform erythroderma, Netherton's syndrome, and neutral lipid storage disease); some forms require frozen sections to demonstrate fat (neutral lipid storage disease) or enzyme activity (Sjögren-Larsson syndrome). Protein electrophoresis and enzymology are necessary for X-linked recessive ichthyosis. A close liaison with the clinicians is essential for the diagnosis of all types of ichthyosis, and combined studies including routine histopathology, electron microscopy, and frozen sections may be required for the diagnosis.

First trimester DNA-based exclusion of recessive dystrophic epidermolysis bullosa from chorionic villus sampling

A 28-year-old woman, who previously had had a child affected with the hereditary blistering skin disorder, recessive dystrophic epidermolysis bullosa, presented at 7 weeks' gestation for prenatal diagnosis. Genomic DNA, obtained from her, her husband (who is a first cousin), their unaffected child, and their previously affected child, was used to screen all 118 exons of the type VII collagen gene (COL7A1) by polymerase chain reaction (PCR) amplification followed by heteroduplex analysis of the PCR products. Established common polymorphisms within the NC-1 region of COL7A1 were informative for both the normal maternal and paternal alleles. In addition, a putative homozygous mutation, a G to C transversion at nucleotide position 7708, was identified in the affected child. This substitution converts a glycine residue (GGT) within the Gly-X-Y region of the type VII collagen triple helix into an arginine residue (CGT), and leads to the creation of a new MnlI restriction site. Both parents and the healthy sibling were shown to be clinically normal heterozygous carriers of this mutation. A chorionic villus biopsy was performed at 10 weeks' gestation and DNA was extracted from the villi. Assessment of informative intragenic markers, and the putative mutation, revealed that the fetus had inherited both the normal maternal and paternal COL7A1 alleles. Thus, first trimester DNA-based prenatal diagnosis predicts that this child is neither affected with recessive dystrophic epidermolysis bullosa, nor is an unaffected carrier of this genodermatosis.

Junctional epidermolysis bullosa and pyloric atresia: a distinct entity. Clinical and pathological studies in five patients

Junctional epidermolysis bullosa (JEB) associated with pyloric atresia (PA) is a distinct entity which is inherited as an autosomal recessive disorder. We describe five patients with this association; four died in the neonatal period and one is still alive at 4 years of age. The cutaneous lesions in these patients are identical or similar to those in other JEB subtypes. Urinary tract involvement is part of the syndrome and presents a problem for long-term survival. Using the monoclonal antibody GB3 we investigated skin biopsies from three of our patients and showed normal expression in all of them, unrelated to the outcome of their disease. This indicates that the GB3 monoclonal antibody is without prognostic significance in this syndrome. It is clear that JEB with PA is a distinct entity. The molecular basis as yet is unknown.

Use of type VII collagen gene (COL7A1) markers in prenatal diagnosis of recessive dystrophic epidermolysis bullosa

Generalised recessive dystrophic epidermolysis bullosa (EB) is a severe inherited disease in which patients suffer from blistering and scarring of the skin and mucous membranes after minor mechanical trauma. Tight genetic linkage has been established to the type VII collagen gene (COL7A1) at 3p21, with no evidence of locus heterogeneity. Several COL7A1 mutations have now been identified in recessive dystrophic EB patients. Prenatal diagnosis has been performed by examination of a fetal skin biopsy taken at about 16 weeks' gestation, and relies on identification of characteristic ultrastructural and immunohistochemical changes. We have now achieved a first trimester prenatal diagnosis using intragenic and flanking COL7A1 markers in a pregnancy at risk for recessive dystrophic EB. Segregation of the informative markers predicted the baby would be an unaffected carrier. The pregnancy continued to term and a healthy baby was born, confirming this result.

Late-infantile Batten disease: purification of the subunit c of the mitochondrial ATP synthase from storage material

The accumulation of subunit c of the mitochondrial ATP synthase in late-infantile neuronal lipofuscinosis (LINCL) and juvenile neuronal lipofuscinosis (JNCL) is well documented. The purification of the subunit from diverse sources has been reported previously, although not from the brain of Batten disease patients. This proteolipid has now been purified from late-infantile Batten disease brain. The procedures used were an original combination of the conventional solubilisation, differential centrifugation, organic solvent extractions, preparative gel electrophoresis, and FPLC. Gel filtration of the purified protein indicated molecular mass equal to or greater than 2 x 10(6) Da; however, electrophoresis of this pure protein suggested a molecular mass of approximately 3,500 Da, which is a characteristic of subunit c. The pure protein may be solubilised in aqueous buffer containing < 1% lithium dodecyl sulphate (LDS). The protein binds dicyclohexylcarbodiimide (DCCD) and shows immunoreactivity to antibodies raised against ovine storage bodies.

Bone marrow transplantation in Batten disease (neuronal ceroid-lipofuscinosis). Will it work? Preliminary studies on coculture experiments and on bone marrow transplant in late infantile Batten disease

Lymphocytes from a patient with preclinical late infantile Batten disease were cultured alone and with lymphocytes from donors, and the fate of the curvilinear inclusions characteristic of the disease was monitored by electron microscopy. There was no evidence of transfer of deficient enzyme or factor that might have caused removal of the stored material, and the curvilinear profiles remained in the cultured cells without signs of degradation. Cells stimulated to divide with phytohaemaglutinin did not exhibit storage in culture suggesting that storage is a function of the age of the cell. The patient received a bone marrow transplant at 2 7/12 years while still clinically unaffected, and the effect on lymphocytes and cells in skin and rectal biopsies was monitored by electron microscopy over a period of 9 months until the donor marrow became displaced by the host cells. He has had one seizure and now has neurophysiological evidence of late infantile Batten's disease. Bone marrow transplant may have no effect on material already stored but might prevent further build-up and halt the onset of the clinical symptoms although very recent studies on early (fetal) transplants in sheep with a form of Batten disease have shown no benefit.

Tissue and cellular distribution of subunit c of ATP synthase in Batten disease (neuronal ceroid-lipofuscinosis)

The major protein component of the storage bodies in the late infantile (LIB) and juvenile (JB) forms of Batten diseases is subunit c of ATP synthase (subunit c). Ultrastructurally the stored material may appear as curvilinear bodies, fingerprint profiles, or a mixture of both, dependent upon the form of Batten disease and the cell type. The mnd/mnd mouse, an animal model for Batten disease, also stores subunit c and has loosely stacked lamellae within the neurons of the brain and in other cells and tissues. Using a range of tissue samples, immunolocalization, using avidin-biotin techniques at the LM level and postembedding immunogold-labelling (5 nm) with silver enhancement at the EM level, were used to investigate specific subunit c immunoreactivity. Subunit c storage was displayed in a number of cells, including neurons, muscle cells, adipocytes, macrophages, endothelial and some epithelial cells, and exocrine and endocrine cells. By EM, subunit c was localized to all curvilinear-type storage bodies, but to nowhere else within the cell. It was not present over fingerprint profiles, the characteristic storage pattern of neurons within the JB gut, possibly due to steric factors. Preliminary studies in the mnd mouse showed subunit c immunoreactivity localized to storage profiles seen ultrastructurally in neurons of the brain, and liver and heart cells. We suggest that accumulation and distribution of subunit c within a variety of cell types, and its consistent absence in others, may be related to the particular cell type's longevity and its metabolic demand.

The natural history of human dermatosparaxis (Ehlers-Danlos syndrome type VIIC)

Dermatosparaxis (Ehlers-Danlos syndrome type VIIC) has only recently been identified in human subjects. Although well documented in animals, to date only three human cases have been recorded, all aged 2 years or under. We document a 15-year-old girl with this newly recognized condition to emphasize the remarkable similarity of physical signs in all four cases. The striking skin fragility which attends the phenotype is highly distinctive, so that the diagnosis may be suspected on clinical grounds. The confirmatory diagnostic procedures are discussed.

Antigenic expression of integrin alpha 6 beta 4 in junctional epidermolysis bullosa

Integrin alpha 6 beta 4 is a major component of hemidesmosomes, considered to play a central role in the adhesion of basal epidermal cells to the underlying dermis. It is therefore of considerable interest in the study of the aetiology of inherited blistering disorders. We have examined the immunohistochemical characteristics of skin from 16 patients with epidermolysis bullosa using two antibodies directed against epitopes on the beta 4 subunit of alpha beta 4 integrin (G71, 3E1), one antibody directed against an epitope on the alpha 6 subunit (GoH3), GB3 an antibody for nicein, and LH7.2, an anticollagen type VII antibody. All 10 patients with junctional epidermolysis bullosa showed markedly reduced or no immunoreactivity with G71. These patients included two with GB3-positive junctional epidermolysis bullosa associated with pyloric atresia, and four with other subtypes. By contrast, five patients with dystrophic epidermolysis bullosa and one patient with epidermolysis bullosa simplex showed normal immunoreactivity with G71. In this study, G71 is shown to have a high specificity and sensitivity for the diagnosis of junctional epidermolysis bullosa. Immunoreactivity with 3E1 and GoH3 was normal in most patients, consistent with published reports showing normal immunoreactivity with other beta 4 and alpha 6 subunit antibodies. The data suggest a modification of the beta 4 subunit of integrin alpha 6 beta 4 at the dermo-epidermal junction in junctional epidermolysis bullosa.

Neutral lipid storage disease. Case report and lipid studies

A 9-year-old boy of Greek-Cypriot origin had been diagnosed at the age of 3 years as suffering from non-bullous ichthyosiform erythroderma. However, he also had hepatomegaly and abnormal liver function tests, biochemical evidence of myopathy, early cataracts, and lipid vacuoles in white blood cells and basal keratinocytes. A diagnosis of neutral lipid (triglyceride) storage disease was confirmed by lipid studies on cultured fibroblasts.

Laryngo-onycho-cutaneous syndrome: an inherited epithelial defect

Three children with an unusual but clearly defined combination of clinical findings that appear to have been inherited in an autosomal recessive manner are described. All had developed laryngeal abnormalities, chronic skin ulceration, nail dystrophy, and conjunctival disease in infancy. In every case, dental enamel was hypoplastic and both skin and mucosal surfaces demonstrated increased susceptibility to trauma. Progression of disease occurred, to life threatening respiratory obstruction in two cases and to effective blindness and fatal respiratory obstruction in the third child. All of these children came from the Pakistani ethnic group. No medical treatment has halted progression of this disease but laser therapy has been partially successful in alleviating laryngeal manifestations. Ultrastructural and immunohistological examination of unaffected skin was undertaken in each child. No abnormality was found in the child with the mildest clinical disease. Both of the other children showed abnormal hemidesmosomes on ultrastructural examination. The most severely affected child also had abnormally weak immunoreactivity with antibodies G71 and GB3 directed against basal cell alpha 6 beta 4 integrin and the basement membrane glycoprotein nicein respectively. These abnormal findings are also seen in skin from patients with junctional epidermolysis bullosa. These three children have the laryngo-onycho-cutaneous syndrome, which may not be rare in their ethnic group. The available clinical and pathological evidence is consistent with this syndrome being caused by an inherited defect affecting the lamina lucida of the skin basement membrane zone. The laryngo-onycho-cutaneous syndrome may therefore represent a new and distinctive type of junctional epidermolysis bullosa.

A new point mutation associated with mitochondrial encephalomyopathy

Point mutations in the mitochondrial gene tRNA leucine(UUR) have been associated with maternally inherited mitochondrial myopathies including the MELAS syndrome (Mitochondrial Myopathy Encephalopathy Lactic acidosis and Stroke-like episodes). We describe a further mutation in tRNA leucine(UUR) in a patient with mitochondrial encephalomyopathy, pigmentary retinopathy, dementia, hypoparathyroidism and diabetes mellitus. The mutation was heteroplasmic in the proband's blood (30%) and muscle (76%); it was present at high levels in the proband's affected mother (50% in muscle), and at low levels (< 10%) in blood, muscle and fibroblasts of an unaffected sister. The mutation was not found in 121 normal controls or 35 other patients with mitochondrial disorders. The mutation is at a highly conserved position in the tRNA molecule, close to the 3,243 mutation which is associated with more than 80% of MELAS cases. Further more, both mutations lie within a possible transcriptional control region. This finding adds further support to the evidence that mutations in this region and in other mitochondrial tRNA genes may cause disease.

Fetal tissue involvement in the late infantile type of neuronal ceroid lipofuscinosis

Prenatal diagnosis in a pregnancy at risk for late infantile neuronal ceroid lipofuscinosis (Batten's disease) was undertaken at 17 weeks' gestation by ultrastructural examination of amniotic fluid cells. The presence of curvilinear profiles indicated an affected fetus and the diagnosis was confirmed, after the pregnancy was terminated, by the finding of many typical curvilinear profiles in multiple tissues which included skin, amnion, umbilical vessels, blood, liver, and brain. Comparison between the involved cells in the amniotic fluid and fetal tissues suggests that these cells are probably derived from the periderm, and possibly also from the amnion. The prominent presence of cytosomes in the periderm and intermediate cells of the fetal epidermis and occasionally also in the endothelial cells of the dermis suggests that fetal skin may be a useful alternative site for assessing fetal involvement. Control specimens of the amniotic fluid, fetal skin, amnion, and liver showed no similar cytosomes. However, some control amniotic fluid samples did contain cells with large collections of irregular trilaminar membranes, and these could be open to misinterpretation. It is important that only typical curvilinear profiles are considered as an indication of an affected pregnancy.

Niemann-Pick disease type C: diagnosis and outcome in children, with particular reference to liver disease

The records of 52 children with Niemann-Pick disease type C were reviewed to establish whether the disease process and outcome varied with the initial clinical pattern; 34 children (65%) had cholestatic liver disease and hepatosplenomegaly in infancy; 18 were seen at a mean age of 4 years with splenomegaly or neurologic disease or both. Of the 34 children with early cholestatic liver disease, three died in the neonatal period; cholestasis and hepatomegaly subsided in the remaining 31 children, although splenomegaly persisted. Of these 31 children, 15 had persistent liver disease with elevated aminotransferase values. Serial liver biopsy specimens showed that 3 of the 15 children had normal architecture and 12 had hepatic fibrosis, with progression to cirrhosis in 5. No other significant morbidity or additional deaths were associated with the liver disease. The clinical importance of persistent liver disease was overshadowed by the subsequent development of severe neurologic disease. There was no difference in the age at onset of the disease (mean, 4.5 years) or in the pattern of neurologic disease, including supranuclear ophthalmoplegia, whether or not the child had early liver disease. Overt neurologic disease has not yet developed in seven surviving children with liver disease at onset. Sixty-seven percent of children died during the study; the main cause of death was bronchopneumonia. We conclude that the diagnosis of Niemann-Pick disease type C should be considered in patients with unexplained neonatal hepatitis, especially if splenomegaly is a persistent feature. Because liver biopsy specimens may not demonstrate storage cells, bone marrow aspiration to detect the characteristic storage cells is recommended in such patients.

Epidermolysis bullosa simplex with mottled pigmentation

A family in which epidermolysis bullosa simplex and mottled pigmentation are inherited as an autosomal dominant disorder is described. Clinical features include: non-scarring blistering, mainly affecting the limbs, mottled pigmentation, predominantly affecting the trunk and neck, warty hyperkeratotic papules of the palms and soles, small red scaly plaques, and skin atrophy. Histology showed an atrophic epidermis, basal cell lysis and significant colloid body formation in an infant from the family.

Motor neuron degeneration of mice is a model of neuronal ceroid lipofuscinosis (Batten's disease)

Pathological studies of mice homozygous for the motor neuron degeneration (Mnd) mutation show abnormalities similar to those of the human neuronal ceroid lipofuscinoses: sudanophilic, autofluorescent intraneuronal inclusions that are immunoreactive with antibodies to subunit c of mitochondrial ATP synthase. Ultrastructurally, the inclusions have the pentalaminar structure characteristic of some form of human neuronal ceroid lipofuscinosis and of canine and ovine models of neuronal ceroid lipofuscinosis. Similar inclusions are observed in many somatic organs and in the retina, which develops photoreceptor degeneration. This mutation, previously considered a model of amyotrophic lateral sclerosis, may be a useful model for molecular and genetic studies of human neuronal ceroid lipofuscinosis because mice have been well characterized genetically. Since they are inexpensive to breed and maintain, they can also be used to test therapeutic interventions.

Mucolipidosis type IV. Presentation of a mild variant

The authors report a 16-year-old girl with mucolipidosis type IV. She was referred because of deteriorating vision over the past three years. Corneal clouding with the appearance of cornea verticillata and retinal dystrophy were the main ophthalmological findings. Except for clumsiness no psychomotor retardation was present. Ultrastructural analysis of a conjunctival biopsy and cultured fibroblasts suggested a diagnosis of mucolipidosis type IV which was confirmed by biochemical studies. This patient represents the mildest described presentation of mucolipidosis type IV.

Intestinal pseudo-obstruction with deficient smooth muscle alpha-actin

We describe a 48-year-old woman with chronic constipation since early childhood who has an intestinal myopathy associated with a hitherto undescribed absence by immunostaining of smooth muscle alpha-actin confined to the intestinal circular muscle. There were no abnormalities in other contractile proteins (myosin, tropomyosin, filamin, caldesmon or desmin) and despite the abnormality of a contractile protein isoform in the circular muscle, no significant morphological changes were identified by light microscopy or ultrastructural examination. A possible developmental mechanism for the observed change is proposed. The use of specific antibodies to isoforms of contractile proteins may have potential value in the study of intestinal myopathies.