Hannes Blöndal

The cerebral hemorrhage-producing cystatin C variant (L68Q) in extracellular fluids

A variant of the normal extracellular cysteine protease inhibitor cystatin C (L68Q-cystatin C), is the amyloid precursor in hereditary cystatin C amyloid angiopathy (HCCAA). It has been suggested that the mutation causes cellular entrapment ofL68Q-cystatin C in vivo and that the variant protein is not secreted to extracellular fluids. In order to test this hypothesis, we used matrix-assisted laser desorption ionization time-of-flight mass spectrometry in an effort to demonstrate the presence ofL68Q- along with wildtype cystatin C in plasma and cerebrospinal fluid (CSF) of HCCAA-patients. Plasma from all five investigated HCCAA-patients contained both L68Q- and wildtype cystatin C. The presence of approximately equal amounts of cystatin C dimers and monomers was demonstrated in plasma from HCCAA-patients, whereas only monomers could be found in normal plasma. L68Q-wildtype-cystatin C heterodimers seem to be present in the dimeric cystatin C population. CSF from six HCCAA-patients also contained cystatin C-dimers and monomers, but the dimeric fraction was minute. CSF from control patients did not contain dimeric cystatin C These results suggest that the milieu of L68Q-cystatin C is important for its stability and dimerization status and that certain milieus might hinder its further development into oligomers, amyloid fibrils and other precipiting aggregates.

Skin deposits in hereditary cystatin C amyloidosis

Clinically normal skin from 47 individuals aged 9–70 years was investigated. Cystatin C amyloid deposits were found in various locations of the skin by light and/or electron microscopy, in all 12 patients with a clinical history of hereditary cystatin C amyloidosis (HCCA). Six asymptomatic individuals, who had the Alu 1 restriction fragment length polymorphism (RFLP) marker reported to cosegregate with the disease, also had cystatin C amyloid deposits in the skin. Three asymptomatic individuals (age 17–46) belonging to the HCCA families were without amyloid in the skin but had Alu 1 RFLP marker. Skin from 12 individuals who served as controls and skin from 14 close relatives of the patients was negative for amyloid. Punch biopsy of the skin is a simple procedure which is of value for the diagnosis of HCCA, even before the appearance of clinical symptoms. This method might also be of use in following progression of the disease.

Incidence and prevalence of multiple system atrophy: a nationwide study in Iceland

Background Multiple system atrophy (MSA) is a neurodegenerative disorder characterised by autonomic dysfunction with parkinsonism (MSAp) or cerebellar (MSAc) symptoms. At autopsy, α-synuclein inclusions in glial cells of the brain are needed to confirm a definite diagnosis. We determined the 10 year incidence of MSA, point prevalence and survival in a well defined population with a high number of neurologists. Methods Cases were identified from the only neurology department and all practising neurologists in Iceland, over a 10 year period. The diagnosis of MSA was in accordance with the Second Consensus Criteria of MSA. Findings 19 incidence cases were diagnosed with MSA (11 women, eight men) during the study period, giving an average annual incidence of 0.7:100 000 (95% CI 0.4 to 1.1). Ten cases were alive on the prevalence day, giving a point prevalence of 3.4:100 000 (95% CI 1.6 to 6.3). 16 of the cases had probable and three possible MSA; 16 had MSAp and three had MSAc. Mean age at symptom onset was 65 years and mean age at diagnosis was 68 years. Patients were followed for an average of 31 months, and 15 died during the follow-up period. Survival from symptom onset was mean 5.7 years. The 1 and 5 year survival rates from diagnosis were 74% and 28%, respectively. Interpretation We reported on the incidence of MSA (both MSAp and MSAc) in a nationwide study where a definite diagnosis of MSA was confirmed in four out of five patients autopsied. We found survival to be shorter than reported in other studies.

Presence of non-fibrillar amyloid beta protein in skin biopsies of Alzheimer's disease (AD), Down's syndrome and non-AD normal persons

A total of 66 skin biopsies from persons with Alzheimers disease (AD) or Downs syndrome (DS) and from persons without AD were used in this study. The age range was from 7 to 89 years. Positive immunoreactivity of skin biopsies to monoclonal antibody 4G8, which is reactive to amino acid residue 17–24 of synthetic amyloid β protein (Aβ), and 4G8-Fab (the antigen-binding fragment of 4G8 IgG, reactive only to amyloid plaque) was observed in the epidermis-dermis junction or the basement membrane of the epidermis and in some blood vessels of the biopsy skins of 13/18 (72%) AD, 9/10 (90%) DS, and 14/38 (37%) non-AD control cases. The Fisher exact probability test revealed a significant difference (P=0.0415 one-tailed) in immunoreactivity between AD and age-matched controls. There was also a significant difference (P=0.0152 one-tailed; P=0.0200 two-tailed) between DS and age-matched control in the same test. Immuno-gold electron microscopy examination of these cases with positive immunoreactivity revealed that the gold particles were deposited along the basement membrane of the epidermis. Amyloid fibrils were not observed in the regions with gold particles. Results of this study suggest that Aβ is associated with the basement membrane of skin and is present in amorphous, non-fibrillar form as soluble Aβ.

Progressive dementia and leucoencephalopathy as the initial presentation of late onset hereditary cystatin-C amyloidosis Clinicopathological presentation of two cases

Hereditary Cystatin-C Amyloidosis (HCCA) is a genetic disorder in Icelandic families in which a defective cystatin-C amyloid protein is deposited in the walls of small and middle sized arteries. Cerebral vessels are most affected, resulting in recurrent cerebral hemorrhages and infarctions, usually with onset of clinical symptoms in the twenties or thirties and a rapidly deteriorating clinical course. The disease can be diagnosed by a skin biopsy in symptomatic patients. We report two patients (father and daughter) who did not have a known family history of the disorder and presented late in life with a progressive dementia, associated with cerebral hemorrhages in the younger patient. Cerebral MRI and CT scans of this patient showed extensive leukoencephalopathic changes. Brain tissue samples from both patients showed immunohistochemical reaction to cystatin-C in small and medium-sized cerebral arteries and extensive cortical and white matter microinfarctions. The amyloid changes were less severe in the older patient and a colocation of beta-amyloid protein and cystatin-C was observed in addition to neurofibrillary tangles and senile plaques. Subcortical and cortical infarctions were also observed. HCCA may present late in life with progressive dementia as the only clinical manifestation, reflecting a multi-infarct syndrome secondary to the amyloidosis. A coexpression of cystatin-C and beta protein may occur as in other cerebral amyloid disorders, probably as age-specific changes.

Distribution of Cystatin C Amyloid Deposits in the Icelandic Patients with Hereditary Cystatin C Amyloid Angiopathy

Cystatin C, a basic microprotein inhibitor of lysosomal proteinases is a precursor of the amyloid fibril deposition in patients with hereditary cystatin C amyloid angiopathy (HCCAA) in Iceland. Cystatin C amyloid deposits were demonstrated immunohistochemically in the following areas. Firstly within the CNS in practically all arteries and arterioles throughout the CNS. Massive cystatin C amyloid was also present in interstitial tissue of the basal ganglia and the hippocampus, especially perivascularly. Spinal pia mater showed positive immuno-staining in all cases as did frequently the arachnoid and arachnoid granulations. Secondly, outside the CNS cystatin C amyloid deposits were demonstrated in the walls of small arteries in all lymphnodes investigated independent of localization in the body. Amyloid material was also detected in the inter-lobular connective tissue of the submandibular salivary gland. These findings suggest that the diagnosis of HCCAA can now be supported by two laboratory methods: Estimation of cystatin C in the cerebrospinal fluid and immunohistochemical study of lymphnode biopsies.

Tumours in Iceland 15. Ependymoma

Thirteen ependymomas reported to the Icelandic Cancer Registry during a 32‐year period (1955–1986) were histologically reviewed and reclassified according to the WHO Histological Typing of Tumours of the Central Nervous System. The annual incidence rate of ependymoma was 0.20/100.000. Clinical observations and data on biological behaviour and immunohistochemistry are presented. Four tumours were supratentorial, six infratentorial and three intraspinal. There were ten males and three females with a mean age of 32 years (range 2.5–68). The mean postoperative survival of nine surgically treated patients was 35.5 months. Histologically, eight tumours were classical ependymomas, three anaplastic and two myxopapillary. Of 11 tumours stained for GFAP, nine were positive. Nine of 10 tumours tested were positive for vimentin, five for NSE and four for S‐100. None of the 10 tumours showed reactivity with AFP, CEA, chromogranin, desmin, factor VIII, keratin or neurofilament.

An isolate of families with hereditary cystatin C amyloid angiopathy and cerebral haemorrhage in the south of Iceland

A previously unreported cluster of families containing 29 members with hereditary cystatin C amyloid angiopathy and cerebral haemorrhage is discribed. Two living members, a mother and her daughter had serious cerebral haemorrhage at the age of 35 and 29 years respectively. Their diagnosis is supported by low values of cystatin C in their cerebrospinal fluids and Congophilic material in the submandibular lymphnode and submandibular salivary gland which showed strong immune reactivity to specific anti-cystatin C antisera. The two geographically separate family isolates are most probably due to the same defective gene present in Icelanders for at least 2–3 centuries.