Fukuyama type congenital muscular dystrophy (FCMD) is an autosomal recessive severe muscular dystrophy associated with an anomaly of the brain. Twenty-one FCMD families, 13 of them with consanguineous marriages, were analysed by genetic linkage analyses with polymorphic microsatellite markers to map the FCMD gene. Significant lod scores were obtained with the markers D9S58 (Zmax = 5.81 at theta = 0.06), D9S59 (Zmax = 4.33 at theta = 0.02), and HXB (Zmax = 3.28 at theta = 0.09) on chromosome 9q31-33. Multipoint analysis placed FCMD between D9S58 and D9S59, with a maximum lod score of 16.93. These markers will be useful for presymptomatic, prenatal and carrier diagnosis of family members carrying FCMD, and they represent important resources for the identification of a gene responsible for FCMD.

The pathological findings for a sural nerve biopsy specimen in a case of neonatal adrenoleukodystrophy are described. The density and total number of myelinated fibers in the patient showed no significant changes compared with controls. On electric microscopy, however, thickness of the myelin was smaller in the patient than in controls. Some linear or trilamellar inclusion bodies were found in Schwann cells and fibroblasts, similar to those found in X-linked adrenoleukodystrophy. Büngner's bands were also seen on electron microscopy, and myelin ovoids and balls were seen in teased fibers. These results show that a sural nerve biopsy is useful for the diagnosis of neonatal adrenoleukodystrophy. We suspect that axonal or neuronal degeneration occurs with changes in myelin in neonatal adrenoleukodystrophy.

The sural nerves of 2 siblings, 7 and 6 years of age with Group A xeroderma pigmentosum, were biopsied. The densities of myelinated fibers, 5,808/mm2 and 5,163/mm2, respectively, were strikingly decreased in comparison to control data. Both large and small myelinated fibers were reduced. Electron microscopy demonstrated many collagen fibers in the endoneurium and some collagen pockets. The loss of myelinated fibers was less severe than in previously reported patients. This discrepancy may be due to age differences at biopsy; our patients were biopsied at the ages of 7 and 6 years, while those patients reported previously were 10 years of age or older. The incidence of neurologic manifestations in xeroderma pigmentosum may increase after 6 years of age.

A boy diagnosed as having glycogenosis type II at three years of age, underwent a sural nerve biopsy at the age of seven years. The distribution of the diameters of myelinated nerve fibers did not clearly demonstrate a bimodal pattern. However, larger fibers of 8 μm or more in diameter were more abundant. This finding correlated with the motor conduction velocity which was within normal limits for his age. A striking feature was the accumulation of glycogen particles in Schwann cells of both myelinated and unmyelinated nerve fibers. The accumulation of glycogen particles was more prominent in Schwann cells of myelinated nerve fibers than in those of unmyelinated ones. The reason for this finding is unclear. The accumulation of glycogen particles in nerve fibers was less than that found in muscle fibers. These morphologic differences between muscle and peripheral nerve fibers may represent an intrinsic difference between the two tissues; glycogen turnover may be faster in muscle than in nerve cells.

We report the case of a 16-year-old girl with a variant form of citrullinemia who had been treated with anticonvulsants for uncontrolled epilepsy during the last 4 years. The diagnosis of citrullinemia was made because she had elevated values for serum citrulline (about 10 times control levels), elevated blood ammonia (over 400 micrograms/dl) and reduced activity of argininosuccinate synthetase in the biopsied liver tissue. Her EEG showed high voltage slow activity, but not triphasic waves, when she had high concentrations of blood ammonia. Treatment with a low-protein diet and sodium benzoate resulted in a normalized blood ammonia level, but her plasma citrulline levels remained unchanged. After the therapy she had neither convulsions nor seizure discharges on EEG, even when all anticonvulsant drug therapy was stopped. Thus it is suggested that hyperammonemia may account for the observed abnormal EEG findings, and triphasic waves on EEG are not always recorded in cases of hyperammonemia.

The quantitative histological study was achieved on the sural nerves obtained at autopsy from three neonates without neurological disorders. The distributions of the myelinated fiber diameters were unimodal and the peaks of the size frequency distributions were at 2-3 microns. These findings coincide with those for children under two years of age, and the latter dose with those for children over 2 months old and adults reported up to now. There were many smaller myelinated fibers under 4 microns in the neonates in comparison with in the children over 2 years old or adults. The densities were higher than those for children over 2 months old, and the ratio of unmyelinated to myelinated fibers was approximately twice as large as that in the children over 2 years old.

A 19-month-old girl with moderate hypotonia was studied. Histochemical and electronmicroscopic findings revealed that many skeletal muscle fibers contained an excess amount of glycogen. The phosphorylase reaction was normalized only after activation with 5' AMP. Biochemical studies showed an increased glycogen content and decreased activities of phosphorylase "a" and an active form of phosphorylase kinase, whereas activities of total phosphorylase, total phosphorylase kinase, and cyclic AMP-dependent protein kinase were all in the normal range. Thus, phosphorylase kinase in the patient's muscle seemed to be a variant form, which was activated partially under the physiologic condition. This condition may be inherited as an X-linked recessive trait.

A sural nerve obtained three hours after death from a patient with hypertyrosinemia due to 4-hydroxyphenylpyruvic acid oxidase deficiency was examined. The diameter of the myelinated fibers, as seen on the histogram, was similar to those in an age matched control. However, the number of smaller fibers was greater. Electron-microscopically, the findings of de- and hypomyelination were noted, and occasional dense bodies and multimembranous bodies were seen in some axoplasms. Since his mother was also suffering from hypertyrosinemia, the serum tyrosine level during the fetal and newborn infant periods seemed to be constantly elevated, which may have caused the abnormalities of nerve fibers observed in the present case.

Histological, ultrastructural, and morphometric studies were performed on nerve and muscle biopsies from three patients with de Sanctis-Cacchione syndrome. Sural nerves showed marked loss of the myelinated fibers, in proportion to decrease in nerve conduction velocities and in inverse proportion to the severity of the clinical symptoms, which were related to the survival length. The larger fibers were involved earlier and more markedly than the smaller. The unmyelinated fibers were also decreased in number. Electron-microscopic studies showed the presence of primary degeneration of myelin sheaths or Schwann cells. Muscle biopsies showed grouping of type I and type II fibers in all three patients. Therefore, peripheral nerve involvement in de Sanctis-Cacchione syndrome was suggested to result from chronic degeneration of the neuronal cells and Schwann cells.

Measurements have been made of the diameters of both myelinated and ummyelinated fibers in the sural nerves obtained at autopsy from 10 children without neurological disorders. The distributions of the myelinated fiber diameters were unimodal, except for two cases in which showed bimodal patterns as seen in adults. The second peak in bimodal histograms may appear around age 2 years. The densities of both myelinated and unmyelinated fibers were calculated in the same nerves. The fascicular areas of the same nerves were also measured. The densities of both myelinated and unmyelinated fibers, and the estimated numbers of both myelinated and unmyelinated fibers showed a tendency toward decrease, but the fascicular areas did a tendency to increase with aging. Although a definite proposal regarding the correlation cannot be made at present, it is interesting that the ratio of unmyelinated to myelinated fibers decreases with age. This tendency may be related to development of myelination.