Non-kinetic hyperglycinaemia: prolonged survival in a patient with a mild variant.
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Biomedical subjects
Publications and source records attributed to J E Wraith.
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Magnetic resonance imaging (MRI) of the brain, neck and cervical spine of five patients with the mild variant of Hunter's syndrome (iduronate sulphate sulphatase deficiency, mucopolysaccharidosis Type II, MPS II) are described and compared with the few available reports in the literature. The most prominent abnormalities in the brain include ventriculomegaly and brain atrophy, the presence of well defined cystic areas of decreased signal on T1- and increased signal on T2-weighted images, of the thalamus, basal ganglia and brain stem, and decreased signal on T1-weighted and increased signal changes on T2-weighted sections of the periventricular and subcortical white matter. A giant cisterna magna was present in four patients and a J-shaped sella in three. Thickening of the soft tissue posterior to the odontoid peg was present with associated canal stenosis in all cases resulting in compression of the cervical cord in four cases. All patients had ill-defined decreased signal on T1-weighted and increased signal changes on T2-weighted sections within the cord. In some, this was associated with cord expansion. Airway narrowing was a common finding. Disc dehydration and the classical platyspondyly with antero-inferior beaking of the vertebral bodies was seen.
Histidinaemia is a relatively common inherited metabolic disorder with an incidence similar to phenylketonuria. This paper reports the long term outcome of patients diagnosed by newborn screening in the north west of England. Between 1966 and 1990, 108 infants were diagnosed as having histidinaemia by a regional neonatal screening programme (incidence 1:11,083). A further five children were detected following diagnosis in a sibling. Of the 113, nine were lost to follow up. Infants diagnosed before 1981 (n = 47) were placed on a low histidine diet (225 mg/kg/d) for an average period of 21 months (SD 4.5). All patients were reviewed regularly, Griffiths developmental quotients (DQ) were assessed at 2 and 4 years, and WISC-R intelligence quotients (IQ) at 8, 12, and 18 years. IQ data were converted to standard deviation scores (IQ SDS) to account for increasing IQ norms with time. Neither DQ nor IQ correlated with plasma histidine at diagnosis or with the mean plasma histidine throughout life. Growth was normal in all patients. There was no apparent benefit from a low histidine diet in early childhood. In contrast to other studies, there was no excess of clinical symptoms. On the basis of these findings, histidinaemia is a benign metabolic disorder that does not require treatment.
Bone-marrow transplantation has increased the survival of patients with mucopolysaccharidosis-I. We describe the spinal problems and their management in 12 patients with this disorder who have been followed up for a mean of 4.5 years since transplantation. High lumbar kyphosis was seen in ten patients which was associated with thoracic scoliosis in one. Isolated thoracic scoliosis was seen in another. One patient did not have any significant problems in the thoracic or lumbar spine but had odontoid hypoplasia, which was also seen in three other children. Four of the eight patients in whom MRI of the cervical spine had been performed had abnormal soft tissue around the tip of the odontoid. Neurological problems were seen in two patients. In one it was caused by cord compression in the lower dorsal spine 9.5 years after posterior spinal fusion for progressive kyphosis, and in the other by angular kyphosis with thecal indentation in the high thoracic spine associated with symptoms of spinal claudication.
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Ninety-six alleles (36 alleles of Japanese and 60 of Caucasian origin) from forty-eight patients with mucopolysaccharidosis IVA were investigated for structural gene alterations using Southern blot analysis. All patients had a previously demonstrated deficiency of N-acetyl-galactosamine-6-sulfate-sulfatase and exhibited a wide spectrum of clinical severity. Initially, using the full-length cDNA as a probe, five of 36 chromosomes from the Japanese patients revealed similar rearrangements with respect to DNA digested with BamHI, SacI, and XhoI. Subsequent analysis using seven genomic fragments, covering the entire gene, enhanced the detection of aberrant fragments produced by the above restriction enzymes. Conversely, the 60 chromosomes of Caucasian origin revealed no evidence of large structural rearrangements when analyzed by these methods. There was a statistically significant difference between the two populations (P < 0.01). A severely affected Japanese patient showed structural rearrangements on both chromosomes by means of BamHI blots. An 8.0-kb fragment and a highly polymorphic 7.0-kb to 11.0-kb fragment present in normal individuals disappeared and two aberrant fragments of 11.5 kb and 12.0 kb were observed. Three other Japanese patients also showed these two aberrant fragments, in addition to the normal fragment pattern, and were thus heterozygous for this rearrangement. Interpretation of Southern blots was difficult because of the complexity of polymorphic bands resulting from variable number of tandem repeat elements. However, by utilizing these aberrant fragments or polymorphic bands, carrier detection was effective, even in families with poorly characterized mutations. Hybridization with probe MG-A (5'-end genomic probe in intron 1) showed a 8.4-kb fragment in BamHI blots of one Japanese and one Caucasian patient; XhoI, SacI, and EcoRI blots were normal. Since this BamHI alteration was also observed in one normal control, it appears to be a rare nonpathological polymorphism.
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OBJECTIVES: To investigate the extent to which the abnormalities in cerebral white matter in adolescents and adults with phenylketonuria (PKU) are reversible. METHOD: Magnetic resonance imaging (MRI) of the brain was repeated in 41 patients with PKU (age range, 14 to 49 years) after an interval (median, 9 months; range, 3 to 12 months) of dietary intervention. Scans were scored according to the extent of the white matter involvement. After an initial MRI, five patients returned to a strict low-phenylalanine diet with amino acid supplement; 21 patients started a low-protein diet (1 gm/kg) with amino acids supplement; and 15 patients made no dietary alteration. RESULTS: Scans improved in all five patients who returned to a strict low-phenylalanine diet, in 5 of the 21 patients on the low-protein diet plus amino acid supplement, and in 4 of the 15 patients who made no dietary change. There was a significant association between change in the MRI findings and in the blood phenylalanine concentration (Pearson correlation: r = 0.55; p < 0.0002) and between change in the MRI and in the phenylalanine level at the time of the second scan (r = 0.58; p < 0.0001). Improvement was seen primarily in those in whom phenylalanine levels were reduced to less than 900 mumol/L. There was no obvious change in MRI score after 3 weeks of strict phenylalanine restriction for the two adults who underwent serial scanning. CONCLUSION: The MRI changes in PKU are at least partially reversible by lowering the blood phenylalanine concentration.
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The presenting features of 39 patients with mucopolysaccharidosis (MPS) type IH are described. The mean age at diagnosis was approximately 9 months and it is difficult to see how this can be reduced without consideration of newborn screening. An earlier age at diagnosis is likely to lead to better results following therapy such as bone marrow transplantation. Clinical features which should arouse suspicion of MPS IH include frequent ENT surgery and recurrent herniae. Clinical vigilance is needed for early diagnosis.
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The clinical presentation and results of the initial biochemical and haematological investigations in 11 newborn term infants with propionic acidaemia are described. All patients had neurological symptoms. Only four had clinically important acidosis, but all had a raised blood ammonia. A diagnosis of propionic acidaemia should be considered in all newborn infants with unexplained neurological deterioration even in the absence of a metabolic acidosis.
Mucopolysaccharidosis IVA is an autosomal recessive lysosomal storage disorder caused by a deficiency of N-acetylgalactosamine-6-sulfate sulfatase. The recent isolation and characterization of cDNA and genomic sequences encoding GALNS has facilitated identification of the molecular lesions that cause MPS IVA. We identified a common missense mutation among Caucasian MPS IVA patients. The mutation was originally detected by SSCP, and successive sequencing revealed an A-->T transversion at nt 393. This substitution altered the isoleucine at position 113 to phenylalanine (I113F) in the 622 amino acid GALNS protein and was associated with a severe phenotype in a homozygote. Compound heterozygotes with one I113F-allele mutation have a wide range of clinical phenotypes. Transfection experiments in GALNS-deficient fibroblasts revealed that the mutation drastically reduces the enzyme activity of GALNS. Allele-specific oligonucleotide or SSCP analysis indicated that this mutation accounted for 22.5% (9/40) of unrelated MPS IVA chromosomes from 23 Caucasian patients, including 6 consanguineous cases. Of interest, the I1e 113-->Phe substitution occurred in only Caucasian MPS IVA patients and in none of the GALNS alleles of 20 Japanese patients. These findings identify a frequent missense mutation among MPS IVA patients of Caucasian ancestry, that results in severe MPS IVA when homoallelic, and will facilitate molecular diagnosis of most such patients and identification of heterozygous carriers. In addition to this common mutation, 10 different point mutations and 2 small deletions were detected, suggesting allelic heterogeneity in GALNS gene.
Abnormalities of magnetic resonance imaging (MRI) of the brain occur in some patients with phenylketonuria but the clinical importance of this finding is not clear. In order to determine the frequency and functional significance of changes on MRI we investigated 77 adolescent and adult patients with phenylketonuria. Patients aged 14-49 years and taking a restricted diet of 1 g/kg protein underwent clinical examination, IQ testing, neurophysiological investigation, and MRI of the brain. Patients aged between 10-14 years taking a low phenylalanine diet with amino acid supplements had MRI of the brain only. Biochemical control was assessed from: the lifetime blood phenylalanine determined from the mean blood concentration throughout life; the accumulated time for each patient that phenylalanine was < 120 mumol/L; the accumulated time for each patient that phenylalanine was > 1200 mumol/L); mean blood concentration in the first 4 years of life; and the mean blood phe concentration in the 5 years prior to imaging. MRI changes, compatible with a disturbance in the water content of white matter, were present in all but 1 patient. The severity of abnormality was most strongly associated with the blood phenylalanine concentration at the time of imaging. Clinical and neurophysiological abnormalities were less common and usually mild. 3 patients had prolonged central motor conduction time, 7 had prolonged visual evoked potentials, and 5 had impaired peripheral sensory nerve conduction. There was no significant association between the extent of MRI abnormalities and IQ, and the presence of neurophysiological, or clinical abnormalities. An abnormal brain scan in PKU may reflect present biochemical control rather than indicate significant neurological damage. As yet there is little evidence that in most patients with PKU these MRI changes are of clinical importance.
The airway problems encountered during anaesthesia in all children with mucopolysaccharidoses presenting for a surgical procedure from 1988 to September 1991 are reviewed. Thirty-four patients underwent 89 anaesthetics for 110 procedures. The results reveal a high incidence of airway problems. The overall incidence of difficult intubation was 25% and failed intubation 8%. In those children with Hurler's syndrome, the difficult intubation incidence was 54% and failed intubation incidence 23%. Other potential anaesthetic problems such as cardiac anomalies and obstructive sleep apnoea are also reviewed.
Two mucopolysaccharidosis type I (MPS-I) patients, subjected to bone marrow transplantation (BMT) more than 10 years ago, have recently had their alpha-L-iduronidase genotypes defined. Both patients, homozygous for the relatively common W402X mutation, received BMT when they were 14 and 11 months of age, and are now 12 and 14 years old, respectively. Untreated MPS-I patients, homozygous for W402X, have an extremely severe clinical phenotype with rapid clinical deterioration and death before 6 years of age. The 12-year-old patient, with limited mobility, is coping well at school, while the other patient is wheelchair-bound with severe disability in his lower limbs, and attends a school for the physically handicapped. Both patients have less than normal intelligence with slowly continuing losses. A third MPS-I patients, diagnosed at the age of 6 months, was felt, prior to BMT at 14 months, to have a severe phenotype. Twelve years post-BMT, he is ambulatory, albeit with restricted movement, and has normal intelligence. This patient did not have a defined MPS-I genotype and had alpha-L-iduronidase protein and activity consistent with a less severe outcome than the first two patients. We conclude that BMT has significantly slowed down the clinical regression of the W402X phenotype. We propose that if further gains are to be made, BMT should be performed within the first few months of life. Early diagnosis is therefore essential.