Leo Pažanin

S-adenosylhomocysteine hydrolase deficiency in a human: A genetic disorder of methionine metabolism

We report studies of a Croatian boy, a proven case of human S-adenosylhomocysteine (AdoHcy) hydrolase deficiency. Psychomotor development was slow until his fifth month; thereafter, virtually absent until treatment was started. He had marked hypotonia with elevated serum creatine kinase and transaminases, prolonged prothrombin time and low albumin. Electron microscopy of muscle showed numerous abnormal myelin figures; liver biopsy showed mild hepatitis with sparse rough endoplasmic reticulum. Brain MRI at 12.7 months revealed white matter atrophy and abnormally slow myelination. Hypermethioninemia was present in the initial metabolic study at age 8 months, and persisted (up to 784 μM) without tyrosine elevation. Plasma total homocysteine was very slightly elevated for an infant to 14.5–15.9 μM. In plasma, S-adenosylmethionine was 30-fold and AdoHcy 150-fold elevated. Activity of AdoHcy hydrolase was ≈3% of control in liver and was 5–10% of the control values in red blood cells and cultured fibroblasts. We found no evidence of a soluble inhibitor of the enzyme in extracts of the patients cultured fibroblasts. Additional pretreatment abnormalities in plasma included low concentrations of phosphatidylcholine and choline, with elevations of guanidinoacetate, betaine, dimethylglycine, and cystathionine. Leukocyte DNA was hypermethylated. Gene analysis revealed two mutations in exon 4: a maternally derived stop codon, and a paternally derived missense mutation. We discuss reasons for biochemical abnormalities and pathophysiological aspects of AdoHcy hydrolase deficiency.

S-Adenosylhomocysteine hydrolase deficiency: a second patient, the younger brother of the index patient, and outcomes during therapy

SummaryS-Adenosylhomocysteine (AdoHcy) hydrolase deficiency has been proven in a human only once, in a recently described Croatian boy. Here we report the clinical course and biochemical abnormalities of the younger brother of this proband. This younger brother has the same two mutations in the gene encoding AdoHcy hydrolase, and has been monitored since birth. We report, as well, outcomes during therapy for both patients. The information obtained suggests that the disease starts in utero and is characterized primarily by neuromuscular symptomatology (hypotonia, sluggishness, psychomotor delay, absent tendon reflexes, delayed myelination). The laboratory abnormalities are markedly increased creatine kinase and elevated aminotransferases, as well as specific amino acid aberrations that pinpoint the aetiology. The latter include, most importantly, markedly elevated plasma AdoHcy. Plasma S-adenosylmethionine (AdoMet) is also elevated, as is methionine (although the hypermethioninaemia may be absent or nonsignificant in the first weeks of life). The disease seems to be at least to some extent treatable, as shown by improved myelination and psychomotor development during dietary methionine restriction and supplementation with creatine and phosphatidylcholine.

Intracranial tumors in adult population of the Varazdin County (Croatia) 1996-2004: a population-based retrospective incidence study

SummaryAimTo estimate the incidence of intracranial tumors in the adult population of the Varaždin County, Croatia, for the 1996–2004 period.MethodsSetting: Varaždin County General Hospital and four university hospitals in Zagreb, the capital of Croatia. Study period: January 1, 1996 to December 31, 2004. Incident patients: county residents admitted for newly diagnosed intracranial tumors according to the WHO diagnostic criteria. Demographic data were extracted from the 2001 Croatian census. Incidence rates (IRs) per 100,000 person-years (p-y) and annual IRs (per 100,000 persons) were determined and compared as incidence rate ratios (IRRs) with 95% CI.ResultsFor primary intracranial tumors (PITs), IR was 12.1/100,000 p-y (95% CI: 10.3–14.2), comparable in men and women. The highest incidence was recorded for glioblastoma (IR 4.8, 3.7–6.2) and meningioma (IR 3.1, 2.2–4.2). The incidence of PIT was somewhat greater than that of metastatic tumors (IRR 1.58, 95% CI: 1.22–2.05, P<0.001). Metastatic tumors were more frequent in men than in women, especially metastatic lung tumors (IRR 6.08, 2.32–20.16, P<0.001). IRs of all PIT taken together, neuroepithelial tumors cumulatively, nonepithelial tumors cumulatively, glioblastoma and meningioma were higher in the population aged ≥40 vs. population aged ≤ 39 (all IRRs with 95% CI greater than 1, P<0.05 or < 0.001), comparable in men and women. Women were somewhat older than men at the time of diagnosis of PIT: median difference −6 years (95.1% CI: −10 to −1, P<0.05). Annual IRs for all these tumor categories showed increasing trends over the study period.ConclusionOverall, there was an increasing trend in the incidence of primary intracranial tumors in the Varaždin County. Data did not allow estimation for most of the specific tumor types.

Mitochondrial myopathy associated with a novel 5522G>A mutation in the mitochondrial tRNA Trp gene

We report a novel pathogenic mutation of the mitochondrial transfer RNA (tRNA) gene for tryptophan in a patient with isolated myopathy and persistently elevated creatine kinase. Muscle studies revealed ragged red fibres and decreased activity of respiratory chain complex I and cytochrome c oxidase (COX). Sequencing of the 22 mitochondrial tRNA genes revealed a mutation m.5522G>A, which alters a conserved base pairing in the D-stem of the tRNA for tryptophan. The mutation was heteroplasmic with a mutational load between 88 and 99% in COX-negative fibres. This case contributes to the genetic heterogeneity of mitochondrial diseases caused by mutations in mitochondrial tRNA genes.

Malignant transformation of grade II ganglioglioma to glioblastoma: A case report

Gangliogliomas are well differentiated and slowly growing neuroepithelial tumors composed of neoplastic ganglion cells and neoplastic glial cells corresponding mostly to the World Health Organization grade I tumors. However, some of these tumors disclose histologically more malignant glial component and correspond to grade II or grade III tumors. We report a case of left temporal lobe tumor in a 42-year-old woman fulfilling the diagnostic criteria for atypical (grade II) ganglioglioma with high Ki-67 proliferation index and p53 immunoreactive tumor cells. In spite of gross total removal of the tumor, it recurred eight months after surgery. Histopathological examination of the recurrent tumor revealed that it had undergone malignant transformation into a glioblastoma. This case indicates that gangliogliomas with high Ki-67 proliferating index and p53 immunoreactivity should be carefully monitored for recurrence and malignant progression regardless of their morphological grading and seemingly total surgical removal.

Lipoastrocytoma: A case report

Lipidized tumours of the central nervous system are very rare. Lipidization of tumour cells is a histological hallmark of pleomorphic xanthoastrocytoma and cerebellar neurolipocytoma and has been described in some other primary neuroepithelial tumours such as glioblastoma, cerebral primitive neuroectodermal tumour, central neurocytoma and ependymoma. However, a few cases of lipidized low-grade glial tumours that could not be classified to the fore mentioned categories have been reported, as well. We report a new case of such a tumour occupying the right temporal lobe in a 23-year old woman. Histologically, the tumour was composed of GFAP positive glial cells with areas of complete cell lipidization. More than a two years after the surgery, the patient is well and asymptomatic supporting presumed favourable clinical course of these rare tumours. The recommended treatment plan for these presumably benignant tumours should be continued with radiographic surveillance after the gross total resection.

Expression Levels and Localizations of DVL3 and sFRP3 in Glioblastoma

The expression patterns of critical molecular components of Wnt signaling, sFRP3 and DVL3, were investigated in glioblastoma, the most aggressive form of primary brain tumors, with the aim to offer potential biomarkers. The protein expression levels and localizations in tumor tissue were revealed by immunohistochemistry and evaluated by the semiquantitative method and immunoreactivity score. Majority of glioblastomas had moderate expression levels for both DVL3 (52.4%) and sFRP3 (52.3%). Strong expression levels were observed in 23.1% and 36.0% of samples, respectively. DVL3 was localized in cytoplasm in 97% of glioblastomas, of which 44% coexpressed the protein in the nucleus. sFRP3 subcellular distribution showed that it was localized in the cytoplasm in 94% of cases. Colocalization in the cytoplasm and nucleus was observed in 50% of samples. Wilcox test indicated that the domination of the strong signal is in connection with simultaneous localization of DVL3 protein in the cytoplasm and the nucleus. Patients with strong expression of DVL3 will significantly more often have the protein in the nucleus (P = 6.33 × 10−5). No significant correlation between the two proteins was established, nor were their signal strengths correlated with epidemiological parameters. Our study contributes to better understanding of glioblastoma molecular profile.