Neuronal expression of the fukutin gene

Fukuyama-type congenital muscular dystrophy (FCMD), a relatively common autosomal recessive disorder in Japan, is characterized by severe congenital muscular dystrophy in combination with cortical dysgenesis (polymicrogyria). The gene responsible for FCMD encodes a novel protein, fukutin, which is likely to be an extracellular protein. Pathological study of brain tissue from FCMD fetuses revealed frequent breaks in the glia limitans and basement membrane complex. Disruption of the basal lamina in FCMD muscle was also seen. Thus, structural alteration of the basal lamina appears to play a key role in the pathophysiology of FCMD. To investigate the role of fukutin in brain anomalies, we examined fukutin mRNA expression in the human brain. Northern blot and RT-PCR analysis revealed that the fukutin gene is expressed at similar levels in fetal and adult brain, whereas its expression is much reduced in FCMD brains. Tissue in situ hybridization analysis revealed fukutin mRNA expression in the migrating neurons, including Cajar-Retzius cells and adult cortical neurons, as well as in hippocampal pyramidal cells and cerebellar Purkinje cells. However, we observed no expression in the glia limitans, the subpial astrocytes (which contribute to basement membrane formation) or other glial cells. In the FCMD brain, neurons in regions with no dysplasia showed fair expression, whereas transcripts were nearly undetectable in the overmigrated dysplastic region. These observations suggest that fukutin function may influence neuronal migration itself rather than formation of the basement membrane. Furthermore, differences in mRNA levels among neurons in early developmental stages may partially differentiate normal and abnormal regions.

Age and origin of the FCMD 3'-untranslated-region retrotransposal insertion mutation causing Fukuyama-type congenital muscular dystrophy in the Japanese population

Fukuyama-type congenital muscular dystrophy (FCMD), an autosomal recessive disorder with a high prevalence in the Japanese population, is characterised by severe muscular dystrophy associated with brain malformation (cortical dysgenesis) and mental retardation. In Japan, 87% of FCMD-bearing chromosomes carry a 3-kb retrotransposal insertion of tandemly repeated sequences within the disease gene recently identified on chromosome 9q31, and most of them share a common founder haplotype. FCMD is the first human disease known to be caused primarily by an ancient retrotransposal integration. By applying two methods for the study of linkage disequilibrium between flanking polymorphic markers and the disease locus, and of its decay over time, the age of the insertion mutation causing FCMD in Japanese patients is calculated to be approximately 102 generations (95% confidence interval: 86-117 g), or slightly less. The estimated age dates the most recent common ancestor of the mutation-bearing chromosomes back to the time (or a few centuries before) the Yayoi people started migrating to Japan from the Korean peninsula. This finding makes the molecular population genetics of FCMD understandable in the context of Japan's history and the founder effect consistent with the prevalent theory on the origins of the modern Japanese population.

Marked elevation in serum apolipoprotein E in a case of heterozygous cholesteryl ester transfer protein deficiency

The subject was a 57-year-old Japanese woman with a body mass index of 21.2 kgm(-2). Her serum total cholesterol (TC), triglycerides (TG) and HDL-cholesterol levels were 7.11 mmoll(-1), 0.53 mmoll(-1) and 2.05 mmoll(-1), respectively. She had a marked increase of serum apolipoprotein (Apo) E concentration of 25 mgdl(-1) with normal concentrations of serum Apo A-I, A-II, B, C-II and C-III. Polymerase chain reaction-restriction fragments length polymorphism analysis of the cholesteryl ester transfer protein (CETP) gene from this subject revealed the heterozygous nucleotide change causing a Asp442 to Gly substitution (D442G) in the CETP protein. For comparison, 11 unrelated female subjects with this mutation (age, 57+/-5.1 years; BMI, 22+/-1.5 kgm(-2); TC, 7.23+/-1.16 mmoll(-1); TG, 1.44+/-0.80 mmoll(-1); HDL-C, 2.47+/-0.53 mmoll(-1)) were found to have a serum Apo E concentration of 7+/-1.5 mgdl(-1), about a third of the patient's concentration. The lipoprotein profile of the proband's serum analyzed by disk polyacrylamide gel electrophoresis showed a trace amount of VLDL. A vitamin A fat-loading test showed little increase in serum triglycerides and retinyl palmitate levels compared with control subjects at 2, 4 and 6 h after fat loading. Ultracentrifugation analysis of her serum revealed no detectable Apo E in the VLDL fraction but showed a large amount of Apo E in the HDL fraction, in contrast to a normal control, who had Apo E in the VLDL fraction as well as in the HDL fraction. Sequence analysis of the Apo E gene from the subject showed no nucleotide changes in exon 3 and exon 4, which code the mature Apo E protein, indicating there is no structural abnormality in the Apo E protein. Direct sequence analysis of the LDL receptor gene also did not show any nucleotide change. Based on these findings, it was hypothesized that the marked increase of Apo E in the patient's serum was caused by a decreased transfer of Apo E from HDL particles to TG-rich lipoproteins or impaired uptake of Apo E-containing HDL by LDL receptor or remnant receptor, due presumably to a dysfunction of these receptors in the patient.

Quantitation by (1)H-NMR of dolichol, cholesterol and choline-containing lipids in extracts of normal and phathological thyroid tissue

Proton magnetic resonance spectroscopy at 1.9 T was used to quantify dolichols, cholesterols, choline-containing phospholipids and double bonds in unsaturated acyl chains in lipid extracts of four types of thyroid tissue [normal (n = 27), papillary cancer (n = 15), adenoma (n = 13) and Basedow disease (n = 6)]. In normal thyroid the mean concentrations of dolichol, cholesterol and phospholipids were 1.2, 3.6 and 2.1 micromol/g wet weight, respectively. The concentrations of these lipids exhibited positive mutual correlations and positive correlations with patient age. The increase in dolichol in elderly human thyroid may be due to the accumulation of lysosomes and may help to compensate for the decrease in the activity of lysosomal enzymes and in thyroid hormone production and release. Dolichol concentrations were significantly lower in papillary cancer (0.4 micromol/g) and Basedow disease (0.3 micromol/g) compared to normal thyroid (p < 0.01 and p < 0.05, respectively), while cholesterol was enhanced only in cancer tissue (10.7 micromol/g). Benign adenoma exhibited normal levels of both dolichol and cholesterol. These results suggest that the synthesis and accumulation of isoprenoids are normal in adenoma but not in cancer.

Virus-mediated transduction of apolipoprotein E (ApoE)-sendai develops lipoprotein glomerulopathy in ApoE-deficient mice

Lipoprotein glomerulopathy (LPG) is a unique renal disease characterized by thrombus-like substances in markedly dilated glomerular capillaries, dysbetalipoproteinemia, and elevated plasma concentrations of apoE. Recent studies identified several apoE mutations in patients with LPG, including apoE2(R145P) Sendai (apoE-Sendai). Virus-mediated transduction of apoE-Sendai in apoE-deficient hypercholesterolemic mice resulted in insufficient correction of hypercholesterolemia and a marked and temporal induction of plasma triglyceride levels. In vitro binding studies showed that apoE-Sendai has a reduced affinity for the low density lipoprotein receptor, suggesting that dysbetalipoproteinemia in LPG is caused by the apoE mutation. Furthermore, histological examination revealed marked intraglomerular depositions of apoE-containing lipoproteins in mice injected with apoE-Sendai virus. These LPG-like depositions were detected 6 days after virus injection and were sustained for at least 60 days. Our results demonstrated that apoE-Sendai is an etiological cause of LPG.

Augmentation of mitochondrial reduced glutathione by S-adenosyl-L-methionine administration in ischemia-reperfusion injury of the rat steatotic liver induced by choline-methionine-deficient diet

We examined whether warm ischemia-reperfusion (I/R) damage of the rat steatotic liver can be reduced by administration of S-adenosyl-L-methionine (SAMe). We examined the effect of SAMe on the mitochondrial reduced-glutathione (GSH) pool. Sixty minutes of partial left lobar vascular clamping followed by 2 h of reperfusion were employed for a model of hepatic warm ischemia. Either 5% dextrose or SAMe was injected intraperitoneally 2 h before I/R in steatotic rats (S-D5% or S-SAMe group). Serum liver enzyme concentrations 2 h after reperfusion were significantly lower in the S-SAMe group than in the S-D5% group. The cytosolic and mitochondrial GSH concentrations after I/R were significantly higher in the S-SAMe group than in the S-D5% group (p < 0.05). The cytosolic and mitochondrial oxidized-glutathione/GSH ratios after I/R were significantly greater in the S-D5% group than in the S-SAMe group (p < 0.01). The adenosine triphosphate concentration was higher in the S-SAMe group than in the S-D5% group (p = 0.0515). These results show that hepatocellular and mitochondrial oxidative stress after I/R in the steatotic liver can be reduced by administration of SAMe. The results also show that mitochondrial function and hepatocellular integrity can be restored by administration of SAMe in steatotic rats.

[The effects of human atrial natriuretic peptide on the pediatric recipients of living-related renal transplantation]

We evaluated the effects of human natriuretic peptide (hANP) on the recipients of living-related renal transplantation in children. Anesthesia was maintained with nitrous-oxide and isoflurane in oxygen. The recipients were divided into two groups: the hANP group (n = 8) received continuous infusion of hANP (0.1 microgram.kg-1.min-1), and the control group (n = 5) received no hANP infusion. Intravenous hANP infusion was started at the loading time of fresh frozen plasma in the recipients until the 12 hours after operation. There were no differences between the groups with regards to age, height, body weight, changes in heart rate and systolic arterial pressure, urine volume during operation, and the levels of blood uremic nitrogen and creatinine. The hANP group showed minimal change in CVP during operation and body weight between the values during and after operation compared with control group. The control group needed significantly more fluid than hANP group during operation. We concluded that continuous i.v. hANP infusion in the pediatric recipients of living-related renal transplantation was useful for maintaining sufficient urination and prevention of heart failure or lung edema.

Proton transport by sensory rhodopsins and its modulation by transducer-binding

The study of light-induced proton transfers in the archaeal sensory rhodopsins (SR), phototaxis receptors in Halobacterium salinarum, has contributed important insights into their mechanism of signaling to their cognate transducer subunits in the signaling complex. Essential features of the bacteriorhodopsin (BR) pumping mechanism have been conserved in the evolution of the sensors, which carry out light-driven electrogenic proton transport when their transducers are removed. The interaction of SRI with its transducer blocks proton-conducting channels in the receptor thereby inhibiting its proton pumping, indicating that the pump machinery, rather than the transport activity itself, is functionally important for signaling. Analysis of SRII mutants has shown that the salt bridge between the protonated Schiff base and its counterion Asp73 constrains the receptor in its inactive conformation. Similarly, in BR, the corresponding salt bridge between the protonated Schiff base and Asp85 contributes to constraining the protein in a conformation in which its cytoplasmic channel is closed. Transducer chimera studies further indicate that the receptor conformational changes are transmitted from the sensors to their cognate transducers through transmembrane helix-helix interaction. These and other results reviewed here support a signaling mechanism in which tilting of helices on the cytoplasmic side (primarily outward tilting of helix F), similar to that which occurs in BR in its open cytoplasmic channel conformation, causes structural alterations in the transducer transmembrane helices.

[Azithromycin in dentistry and oral surgery]

Azithromycin has adequate tissue levels for 7 days with a 3 day treatment regimen. The antibacterial activity is excellent. In dental infections, recurrence of infection happens when antibiotics cause a temporary improvement in symptoms but the etiologic agent is not eradicated. Azithromycin produces a "focused" cure and is an appropriate antibiotic for these infections. For this reason, the antibiotic was approved.

In vivo and in vitro evidence for the glycoxidation of low density lipoprotein in human atherosclerotic plaques

Although there have been suggestions that the glycation and oxidation of low density lipoprotein (LDL) might increase its atherogenic potential, little is known about the presence of glycoxidative LDL in human atherosclerotic lesions. We developed specific antibodies against different immunological epitopes of AGE structures, including N(epsilon)-(carboxymethyl)lysine-protein adduct (CML), a glycoxidation product, and structure(s) other than CML (nonCML), and a monoclonal antibody against oxidized phosphatidylcholine (oxPC), as an epitope of oxidized LDL. Immunohistochemical analysis demonstrated that the CML- and oxPC-epitopes were accumulated mainly in macrophage-derived foam cells in atherosclerotic lesions, including fatty streaks and atherosclerotic plaques. On the other hand, the nonCML-epitope and apolipoprotein B were localized mainly in extracellular matrices of atherosclerotic lesions. The CML- and oxPC-epitopes were characterized by a model antigen-generating system using the copper ion-induced peroxidation and/or glucose-induced glycation of LDL. The glycoxidation of LDL caused the formation of CML-epitope with increasing concentrations of copper ion and glucose. It was also formed to some extent in LDL incubated with high concentrations (500 mM) of glucose. However, no CML-epitope was observed in oxidized LDL induced by copper ion alone. On the other hand, the formation of oxPC-epitope in LDL was dependent on copper ion-induced peroxidation, but independent of glucose-induced glycation. The addition of chelators, ethylenediaminetetraacetic acid and diethylenetriaminepentaacetic acid, reduced the increase in electrophoretic mobility and TBARS caused by the peroxidation and glycoxidation of LDL, but had no effects on the formation of fructosamine caused by the glycation and glycoxidation of LDL. Chelators as well as aminoguanidine protected the formation of CML-epitope in glycated or glycoxidative LDL. Although the formation of oxPC-epitope was completely inhibited by the addition of chelators, it was partially protected by aminoguanidine. These in vitro results suggest that the glycoxidative modification of LDL may occur in the arterial intima, and may contribute to the development of human atherosclerotic lesions.

Comparison of gyrA and parC mutations and resistance levels among fluoroquinolone-resistant isolates and laboratory-derived mutants of oral streptococci

Laboratory-derived fluoroquinolone-resistant mutants were obtained by serial passage of Streptococcus sanguis and Streptococcus anginosus isolates on agar containing increasing concentrations of old and new fluoroquinolones, ofloxacin and DU-6859a, respectively. Sequencing of an S. sanguis isolate exposed to DU-6859a showed that resistance was associated with two mutations in the quinolone resistance determining region (QRDR) of the gyrA gene (Ser83-->Phe; Glu87-->Lys), and with a mutation in the parC gene (Ser79-->Ile). However, different mutations in the gyrA gene (Ser83-->Tyr) and parC gene (Ser79-->Phe) were found in a S. sanguis isolate exposed to ofloxacin. A fluoroquinolone-resistant isolate, QR-95101, from a dental infection, had a single mutation in the gyrA gene (Ser83-->Phe) and in the parC gene (Ser79-->Phe). Two fluoroquinolone-resistant mutants, QS-701OFm and QS-701DUm, were obtained from S. anginosus QS-701, by exposure to ofloxacin and DU-6859a, respectively. These mutants showed a common substitution at codon 83 (Ser-->Phe) in the gyrA gene but had different substitutions at codon 87 (QS-701OFm, Glu-->Gln; QS-701DUm, Glu-->Lys). They also had different substitutions at codons 79 and 135 in the parC gene (QS-701OFm, Ser79-->Leu but no change at Glu135; QS-701DUm, Ser79-->Ile and Glu135-->Gln). The resistance levels of the DU-6859a-selected resistant S. sanguis mutant QS-951DUm to DU-6859a, ofloxacin, ciprofloxacin and norfloxacin were higher than those of the ofloxacin-selected resistant mutant QS-951OFm. However, ampicillin susceptibilities of these mutants were not different from the parental strains. In S. anginosus, the DU-6859a-selected fluoroquinolone-resistant mutant QS-701DUm was resistant to all the fluoroquinolones tested, while the ofloxacin-selected mutant QS-701OFm was resistant to three fluoroquinolones, but not DU-6859a. The results indicate that different fluoroquinolones select distinct mutations in the QRDR of the gyrA and parC genes in oral streptococci. The gyrA or parC mutation in oral streptococci may determine the levels of fluoroquinolone resistance.

Underexpression of neural cell adhesion molecule and neurotrophic factors in rat brain following thromboxane A(2)-induced intrauterine growth retardation

Intrauterine growth retardation (IUGR) often results in clinical neurodevelopmental disorders. To clarify the influence of uteroplacental insufficiency on central nervous system development, we have created a model of IUGR in rats using maternal administration of synthetic thromboxane A(2). We investigated expression patterns of neural cell adhesion molecule (NCAM) and reelin in this model by semiquantitative competitive polymerase chain reactions. On postnatal day 2, NCAM expression was decreased in rat cerebral cortex, and reelin expression was decreased in hippocampus from levels in controls without maternal thromboxane exposure. No significant differences in NCAM expression were seen in hippocampus, nor did reelin expression differ in cerebral cortex between control and IUGR groups. We also examined expression of two neurotrophic factors, brain-derived neurotrophic factor (BDNF) and neurotrophin-3 (NT-3). In cerebral cortex the IUGR group showed less BDNF and NT-3 expression than controls. Delay of neuronal migration and histological changes observed in our IUGR rats may be related to altered expression of these molecules.

Abnormal cerebral neuronal migration in a rat model of intrauterine growth retardation induced by synthetic thromboxane A(2)

Many reports have associated intrauterine growth retardation (IUGR) with adverse neurological outcome, but the underlying pathology is imperfectly understood. We have developed a new rat model of IUGR using maternal administration of synthetic thromboxane A(2) (STA(2)). In the present study, the effect of this insult on neuronal migration in the rat cerebral cortex was examined. Bromodeoxyuridine (BrdU), a time-specific cell marker was administered intraperitoneally to the mothers on embryonic day (E) 19. At postnatal day (P) 3, P4, P5, and P6, pups were terminally anesthetized and brains were removed. BrdU-labeled cells were detected immunohistochemically and counted in cerebrum, which was divided into the cortical plate (CP), the intermediate zone, and the subventricular/ventricular zone (SVZ+VZ). Numbers of labeled cells in the three areas over time were compared between IUGR and control animals. Numbers of labeled cells in SVZ+VZ were significantly greater in IUGR than in controls at P3, 5, and 6 (P<0.05). In contrast, labeled cells in the CP were significantly less abundant in IUGR animals than in controls at P3, 4, and 6 (P<0.05). We concluded that neuronal migration was delayed in IUGR rats.

Descending necrotizing mediastinitis due to odontogenic infections

OBJECTIVE

Acute purulent mediastinitis caused by oropharyngeal infection is termed descending necrotizing mediastinitis. Such infections usually have a fulminate course, leading to sepsis and frequently to death. The purpose of this study is to show the importance of early diagnosis, aggressive surgical intervention, and optimal antibiotics chemotherapy in controlling this fatal infectious disease.

STUDY DESIGN

Two patients with descending necrotizing mediastinitis due to odontogenic infection who were treated at our institution are described.

RESULTS

Both patients survived.

CONCLUSIONS

From the patients, 23 different aerobic and anaerobic bacteria were isolated. All of the isolates were susceptible to carbapenem. Early evaluation by means of cervicothoracic computed tomography scanning was extremely useful for diagnosis and surgical planning. Knowledge of anatomic pathways from the mouth to the mediastinum is essential. We believe that tracheostomy is not always necessary. In both of the cases presented, mediastinal drainage was completed through use of a transcervical approach. However, a more aggressive drainage including tracheostomy might be necessary when the infection extends below the carina.

[Preliminary report: first identification of known mutation in the ryanodine receptor gene in a Japanese malignant hyperthermia pedigree]

In Japan, the rate of Ca-induced Ca release (CICR) using skinned fibers of skeletal muscle has been employed as a diagnostic test for malignant hyperthermia (MH) susceptibility, since most of the typical fulminant MH patients showed an enhancement of CICR rate. Recently the Ca releasing channel responsible for the CICR was reported to be mainly the ryanodine binding Ca protein which was identified as the causative site of MH muscle according to recent genetic studies. Among patients with enhanced CICR rate, one point mutation for Arg 2434 His was recognized in a family. Although this site is related to the central core disease (CCD), this pathological change could not be observed in this patient. This is the first report describing a gene mutation in a MH family identified in Japan.

[A patient with advanced gastric cancer who obtained downstaging and underwent radical surgery by neoadjuvant chemotherapy]

The patient was a 74-year-old man with extremely advanced gastric cancer. A CT scan of the abdomen showed enlargement of many huge abdominal para-aortic lymph nodes. Neoadjuvant chemotherapy (NAC) was planned in order to reduce or eliminate the tumor. Two cycles of FLP combination therapy (5-fluorouracil, leucovorin, cisplatin) were given. After NAC, a CT scan revealed marked shrinkage of the No. 16 lymph nodes, and a distal gastrectomy with extended radical lymph node dissection including the No. 16 nodes was performed. The histological effect was judged to be grade 2. There were no viable cancer cells in the No. 16 lymph nodes. The FLP combination therapy as NAC was so effective that it induced downstaging from stage IVb to IIIb.

Clinical significance of p53 functional loss in squamous cell carcinoma of the oropharynx

We examined the frequency of p53 mutations in 38 oropharyngeal squamous cell carcinomas (SCC), using both a yeast functional assay and a conventional immunohistochemical staining method (IHC) to detect p53 mutations. We also explored the clinical importance of p53 mutations in oropharyngeal SCC. An accumulation of p53 protein was detected in 17 of the 38 (45%) tumors by IHC, whereas the yeast-based assay detected 6 additional p53 mutations, for a total of 23 tumors (61%) with p53 mutations. The cDNA sequencing analysis revealed that the 6 mutations undetected by IHC consisted of 3 frameshift, 1 nonsense and 2 missense mutations. Thus, the yeast functional assay was more sensitive than conventional IHC for detecting p53 mutations. Subsequently, the relationship between p53 mutations and the clinico-pathological parameters in oropharyngeal SCC was evaluated using the results of the functional assay. Mutation of p53 was not associated with the patient age, sex, tumor stage or degree of tumor cell differentiation. Interestingly, heavy drinking had a significant positive correlation with the p53 mutation, but heavy smoking did not, suggesting that prolonged exposure to alcohol is more related to p53 mutation in oropharyngeal SCC than to tobacco consumption. Radiation sensitivity was examined by comparing tumor size on magnetic resonance images before and after completion of therapy with 45 Gy radiation, in the 18 cases of T2 oropharyngeal SCC that were initially treated by radiotherapy. The results showed that tumors with wild-type p53 decreased in size significantly compared to those with mutant p53. In 33 patients treated with curative intent, the overall survival after the completion of therapy was better in patients with a wild-type p53 tumor than in patients with a mutant p53 tumor. We conclude that p53 mutation is associated with radiation resistance and a decreased probability of survival in oropharyngeal SCC.

Marked decrease in plasma apolipoprotein A-I and high density lipoprotein-cholesterol in a case with Werner syndrome

The patient was a 39-year-old Japanese male with a body height of 160 cm and weight of 48 kg who was diagnosed as Werner syndrome of homozygote for mutation 4. His plasma total cholesterol (TC), triglycerides (TGs), high density lipoprotein-cholesterol (HDL-C) and apolipoprotein A-I (apo A-I) levels were 7.2, 2.1, 1 mmol/l and 128 mg/dl, respectively. During the clinical course of treatment of this patient, his plasma levels of HDL-C and apo A-I declined drastically to levels of as low as 0.2 mmol/l and 10 mg/dl, respectively, with concurrent reciprocal increase in plasma TG levels. Plasma HDL-C, apo A-I and TG levels gradually returned to original values. Lipoprotein lipase activity and mass in post-heparin plasma were markedly low when the apo A-I and HDL-C levels decreased to 10 mg/dl and 0.21 mmol/l, respectively, and these values improved when the apo A-I and HDL-C levels returned to more normal values of 106 mg/dl and 0.94 mmol/l, respectively. The result of direct sequence of the exon 3 and 4, and the promoter region of the apo A-I gene of the patient revealed no single nucleotide changes. These results suggest that in the present patient, impaired hydrolysis of TGs in TG-rich lipoproteins, is due at least in part to a decreased LPL enzyme level, reduced the formation of nascent HDL, resulting in unusually low plasma levels of HDL-C and apo A-I.

The Fukuyama congenital muscular dystrophy story

Fukuyama congenital muscular dystrophy is one of the most common autosomal recessive disorders in the Japanese population, characterized by congenital muscular dystrophy in combination with cortical dysgenesis (micropolygyria). Recently, we have identified the gene responsible for fukuyama congenital muscular dystrophy on 9q31, which encodes a novel 461-amino-acid protein termed fukutin. Most Fukuyama congenital muscular dystrophy-bearing chromosomes are derived from a single ancestral founder (87%), and a 3 kb-retrotransposal insertion into the 3' untranslated region of this gene was found to be a founder mutation. Two independent point mutations causing premature termination confirmed that that this gene is responsible for Fukuyama congenital muscular dystrophy. Fukuyama congenital muscular dystrophy is the first human disease to be caused by an ancient retrotransposal integration. Fukutin contains an amino-terminal signal sequence, which together with results from transfection experiments suggests that it is an extracellular protein. Discovery of the Fukuyama congenital muscular dystrophy gene represents an important step toward greater understanding of the pathogenesis of muscular dystrophies and also of normal brain development.