Aspartylglucosaminuria in a Canadian family.

Aspartylglucosaminuria (McKusick 208400) is a lysosomopathy associated with aspartylglucosaminidase (L-aspartamido-beta-N-acetylglucosamine amidohydrolase, EC 3.5.1.26) deficiency. It has been most frequently encountered in Finland, where the regional incidence may be as high as 1 in 3600 births. In North America it is very rare, having been reported in only 8 patients. We encountered 4 patients with aspartylglucosaminuria in a Canadian family of 12 siblings. The 4 siblings affected--2 brothers and 2 sisters--were apparently normal at birth; however, their developmental milestones, particularly speech, were slow, and they acquired only a simple vocabulary. Throughout life, there was a progressive coarsening of facial features; 3 had inguinal hernia and recurrent diarrhea; all became severely retarded and by the 4th decade showed evident deterioration of both cognitive and motor skills; 2 exhibited cyclical behavioural changes. Three of the siblings have died, at 33, 39 and 44 years of age. Two died of bronchopneumonia and 1 of asphyxiation following aspiration. In the urine of all 4 siblings, and in the 1 liver examined, we found 2-acetamido-1-N-(4-L-aspartyl)-2-deoxy-beta-D-glucosamine (GlcNAc-Asn) and alpha-D-mannose-(1,6)-beta-D-mannose-(1,4)-2-acetamido- 2-deoxy-beta-D-glucose-(1,4)-2-acetamido-1-N-(4-L-aspartyl)-2-deoxy-beta - D-glucosamine (Man2-GlcNAc2-Asn). Compared with the level of activity in controls, aspartylglucosaminidase activity was less than 2% in fibroblasts from 3 of the siblings, less than 0.5% in leukocytes from 1 sibling, and less than 1% in the liver of 1 sibling, whereas other acid hydrolase activities in these tissues were normal. Ultrastructural studies of skin showed that fibroblasts, endothelial cells and pericytes contained vacuoles with fine reticulo-floccular material. Glial and neuronal cells of the central nervous system showed similar inclusions as well as others composed of concentric or parallel membranous arrays intermingled with lipid droplets.

Acoustic and surface EMG diagnosis of pediatric muscle disease.

The ratio of acoustic myography (AMG) amplitude to surface electromyography (EMG) amplitude is proposed as a measure of mechanical output compared with electrical activity of the contractile system. AMG to EMG ratios were measured from 16 children with muscle disease diagnosed by clinical criteria, EMG, and/or muscle biopsy. These were compared with the ratios from 11 normal volunteers spanning the same age range (7-16 years). AMG to EMG ratios were significantly (P less than 0.01) different for the two populations. Using a linear discriminant function to define the normal range for AMG to EMG ratios yielded a sensitivity of 82% (13 of 16 abnormals diagnosed) and a specificity of 91% (10 of 11 normals). These findings suggest that surface recordings may provide significant diagnostic information in muscle disease. The accuracy may be improved further by using additional muscles (e.g., paraspinals) and evoked twitches.

Tay-Sachs disease: B1 variant.

This first child of non-Jewish parents had nystagmus at 4 months of age, bilateral cherry-red macular spots at 7 months of age, and hyperacusis at 8 months of age; the patient has deteriorated progressively following a clinical course typical of Tay-Sachs disease B variant. Total beta-N-acetylhexosaminidase assayed with 4-methylumbelliferyl-beta-glucosamine (4 MU GlcNAc) as substrate was within the normal range in plasma and cultured dermal fibroblasts and 2/3 the normal mean in leukocytes. The hexosaminidase A activity, assayed with the same substrate in plasma and cultured fibroblasts, approximated Tay-Sachs disease heterozygote levels; however, the activity of hexosaminidase A assayed with 4 MU Glc NAc-6-sulfate in the plasma, leukocytes, and cultured fibroblasts was less than 8, 2, and 1%, respectively of the control mean. This female infant with the B1 variant of Tay-Sachs disease demonstrated an earlier onset and more rapidly progressive course than was observed in 4 of the 5 previously reported patients with this Tay-Sachs disease variant.

Atypical severe muscular dystrophy in a male: genetic implications for female relatives.

Genetic counselling of two younger sisters of a 32-year-old man with a 28-year history of severe progressive muscular dystrophy stimulated efforts to determine his diagnosis and the mode of inheritance. The investigation was complicated by the patient's sudden death during the period of investigation. However, genetic and neurological evaluation, electromyography and nerve conduction studies, serum enzymes and reinterpretation of a muscle biopsy 23 years earlier made it unlikely that inheritance was X-linked, thereby substantially reducing his sisters' risk of bearing affected children. Precise diagnosis, especially of what is not likely in atypically presenting genetic disease, is of paramount importance in managing families at risk for genetic disease in future children. It is an important responsibility of family physicians concerned with preventive genetic medicine.

A variant form of metachromatic leukodystrophy without arylsulfatase deficiency.

The clinical, pathological, and biochemical findings in a young woman with a new variant of metachromatic leukodystrophy (MLD) are reported. The patient showed slow early development and deteriorated further during her first two decades. Nerve conductions were slow, and a sural nerve biopsy showed features of a sulfatide lipidosis. Urinary sulfatide excretion was comparable to that of patients with classic MLD, yet in vitro activity of arylsulfatase A and B and cerebroside sulfatase activity were normal. Skin fibroblasts cultured in medium supplemented with 3H-labeled sulfatide showed accumulation of labeled sulfatide in large amounts, implying a defect in sulfatide hydrolysis in vivo in spite of intact enzyme activity in vitro.

Cerebellar astrocytoma with benign histology and malignant clinical course. Case report.

Juvenile cerebellar astrocytoma characteristically has a very benign course and good prognosis. A case is reported of juvenile cerebellar astrocytoma with massive craniospinal leptomeningeal spread prior to surgical intervention. The patient died 8 months after the onset of symptoms and only 5 weeks after presentation to the hospital. At postmortem examination, it was found that tumor encased the brain and spinal cord. The histology was benign. The literature on cerebellar astrocytoma is reviewed.

The AB-variant of metachromatic leukodystrophy (postulated activator protein deficiency). Light and electron microscopic findings in a sural nerve biopsy.

THe histopathological findings in a sural nerve biopsy of a new distinct variant of metachromatic leukodystrophy (MLD) are compared to those of classical MLD. The clinical and histological features are typical of a sulfatide lipidosis, yet in vitro activities of arylsulfatases A and B and cerebroside sulfatase are normal. Intact skin fibroblasts, when cultured in a medium supplemented with labelled sulfatide, show impaired in vivo sulfatide hydrolysis. A deficiency of the requisite activator protein is postulated.

Ultrastructure and peroxidase of leucocytes in five patients with juvenile form of ceroid lipofuscinoses.

Peripheral leucocytes obtained from five patients with clinical histories and funduscopic findings typical of the juvenile form of the so-called neuronal ceroid lipofuscinosis (NCLF) (synonym: Spielmeyer-Vogt disease) were assayed for peroxidase activity and examined by electron microscopy. The peroxidase levels were considerably lower in three but normal in two patients. Ultrastructurally, the lymphocytes of all five patients showed the presence of tubulo-membranous cytosomes many displaying the fingerprint images at present regarded as being typical for the NCLF. The possible implications of the discrepancy between the morphological observations and the enzymatic findings are discussed.