Clinical, biochemical, neuropathological and molecular findings of the first Polish case of adenylosuccinase deficiency.

Adenylosuccinase (ADSL) deficiency is an autosomal recessive disorder affecting mainly the nervous system. The disease causes psychomotor retardation, frequently with autistic features and epilepsy. ADSL deficiency may be diagnosed by detection of two abnormal metabolites in body fluids--succinyladenosine (S-Ado) and succinylaminoimidazole carboxamide riboside (SAICAr). It is assumed that the former metabolite is neurotoxic. We present clinical, biochemical and neuropathological findings of a child affected by a severe form of ADSL deficiency. She had progressive neurological symptoms that started immediately after birth and died at 2.5 months of age. Macroscopically the brain showed signs of moderate atrophy. Histological examination of all grey matter structures showed widespread damage of neurons accompanied by microspongiosis of neuropile. Cerebral white matter showed lack of myelination in the centrum semiovale and diffuse spongiosis of neuropile. Myelination appropriate for the age was visible in posterior limb of internal capsule, in striatum, thalamus and in brain stem structures but diffuse destruction of myelin sheets was seen with severe marked astroglial reaction with signs of destruction of the cells and their processes. Ultrastructural examination showed enormous destruction of all cellular elements, but astonishingly mitochondria were relatively spared. The neuropathological changes can be considered as the neurotoxic result of metabolic disturbances connected with adenylosuccinase deficiency.

Intrafamilial variability in the phenotypic expression of adenylosuccinate lyase deficiency: a report on three patients.

We report on the striking variable expression of adenylosuccinate lyase (ADSL) deficiency in three patients belonging to a family which originates from Portugal. ADSL deficiency is a rare autosomal recessive disorder of the de novo purine synthesis which results in accumulation of succinylpurines in body fluids. As a result, patients may have variable combinations of psychomotor retardation and/or regression, seizures, autistic features and cerebellar vermis hypoplasia. However, intrafamilial variable expression of the phenotype has not been documented to date in this disease and is not commonly observed in metabolic disorders. Here, while the proband had marked psychomotor regression and progressive cerebellar vermis atrophy, the other two affected patients presented mainly autistic features. Mutation analysis of the ADSL gene revealed the presence of a homozygous R426H mutation in this family. Finally, although ADSL deficiency is a rare disorder, this diagnosis should be considered and assessed using a simple urinary screening method for the presence of succinylpurines in any patient with mental retardation of unexplained origin.

Clinical, biochemical and molecular genetic correlations in adenylosuccinate lyase deficiency.

Adenylosuccinate lyase (ADSL) deficiency (MIM 103050) is an autosomal recessive inborn error of purine synthesis characterized by the accumulation in body fluids of succinylaminoimidazolecarboxamide (SAICA) riboside and succinyladenosine (S-Ado), the dephosphorylated derivatives of the two substrates of the enzyme. Because ADSL-deficient patients display widely variable degrees of psychomotor retardation, we have expressed eight mutated ADSL enzymes as thioredoxin fusions and compared their properties with the clinical and biochemical characteristics of 10 patients. Three expressed mutated ADSL enzymes (M26L, R426H and T450S) were thermolabile, four (A2V, R141W, R303C and S395R) were thermostable and one (del206-218), was inactive. Thermolabile mutations decreased activities with SAICA ribotide (SAICAR) and adenylosuccinate (S-AMP) in parallel, or more with SAICAR than with S-AMP. Patients homozygous for one of these mutations, R426H, displayed similarly decreased ADSL activities in their fibroblasts, S-Ado:SAICA riboside ratios of approximately 1 in their cerebrospinal fluid and were profoundly retarded. With the exception of A2V, thermostable mutations decreased activity with S-AMP to a much more marked extent than with SAICAR. Two unrelated patients homozygous for one of the thermostable mutations, R303C, also displayed a much more marked decrease in the activity of fibroblast ADSL with S-AMP than with SAICAR, had S-Ado:SAICA riboside ratios between 3 and 4 in their cerebrospinal fluid and were mildly retarded. These results suggest that, in some cases, the genetic lesion of ADSL determines the ratio of its activities with S-AMP versus SAICAR, which in turn defines the S-Ado:SAICA riboside ratio and the patients' mental status.

Determination of ribonucleosides, deoxyribonucleosides, and purine and pyrimidine bases in adult rabbit cerebrospinal fluid and plasma.

Purine and pyrimidine base and nucleoside levels were measured in adult rabbit cisternal CSF and plasma by reversed-phase high-performance liquid chromatography. The concentrations of bases, nucleosides, and nucleoside phosphates were similar in plasma and CSF except for the adenosine phosphates and uracil which were higher in the plasma. In plasma and CSF, adenosine levels were low (0.12 microM) and guanosine, deoxyadenosine, deoxyguanosine, and deoxyinosine were not detectable (less than 0.1 microM); inosine and xanthine concentrations were 1-2 microM and hypoxanthine concentrations were approximately 5 microM; uridine (approximately 8 microM), cytidine (2-3 microM), and thymidine, deoxyuridine, and deoxycytidine (0.5-1.4 microM) were easily detectable. In both plasma and CSF, guanine, and thymine were undetectable (less than 0.1 microM), adenine and cytosine were less than 0.2 microM, but uracil was present (greater than 1 microM). Adenosine, inosine, and guanosine phosphates were also detectable at low concentrations in CSF and plasma. These results are consistent with the hypothesis that purine deoxyribonucleosides are synthesized in situ in the adult rabbit brain. In contrast, pyrimidine deoxyribonucleosides and ribonucleosides, and purine and pyrimidine bases are available in the CSF for use by the brain.

Cerebrospinal fluid levels of 2'-deoxycoformycin after systemic administration in monkeys.

2'-Deoxycoformycin (DCF) is an inhibitor of the enzyme adenosine deaminase (ADA) and has shown promise as an antileukemia agent. For the assessment of the extent to which systemically administered DCF crosses into the central nervous system (CNS), rhesus monkeys were given iv boluses of DCF. Simultaneous blood and cerebrospinal fluid (CSF) samples were assayed for DCF levels at times ranging from 10 minutes to 6 hours after the drug was given. Average peak CSF drug levels of 5.5 X 10(-8) M and 3 X 10(-7) M were reached 1 1/2 - 2 hours following injections of 0.25 and 1.0 mg DCF/kg, respectively. The ratio of peak CSF to simultaneous plasma levels was 1 to 10. Data obtained from a patient who had acute lymphocytic leukemia and who was given iv DCF were comparable. Drug levels achieved within the CSF following iv administration of 0.25 mg DCF/kg are similar to those previously demonstrated to inhibit ADA. These results may be important both for understanding DCF-related CNS toxicity and for designing combination chemotherapy with DCF.