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

Clinical considerations in early-onset cerebral amyloid angiopathy

Cerebral amyloid angiopathy (CAA) is an important cerebral small vessel disease associated with brain haemorrhage and cognitive change. The commonest form, sporadic amyloid-β CAA, usually affects people in mid- to later life. However, early-onset forms, though uncommon, are increasingly recognized and may result from genetic or iatrogenic causes that warrant specific and focused investigation and management. In this review, we firstly describe the causes of early-onset CAA, including monogenic causes of amyloid-β CAA (APP missense mutations and copy number variants; mutations of PSEN1 and PSEN2) and non-amyloid-β CAA (associated with ITM2B, CST3, GSN, PRNP and TTR mutations), and other unusual sporadic and acquired causes including the newly-recognized iatrogenic subtype. We then provide a structured approach for investigating early-onset CAA, and highlight important management considerations. Improving awareness of these unusual forms of CAA amongst healthcare professionals is essential for facilitating their prompt diagnosis, and an understanding of their underlying pathophysiology may have implications for more common, late-onset, forms of the disease.

Inherited leukoencephalopathies with clinical onset in middle and old age

The currently widespread use of neuroimaging has led neurologists to often face the problem of the differential diagnosis of white matter diseases. There are various forms of leukoencephalopathies (vascular, inflammatory and immunomediated, infectious, metabolic, neoplastic) and sometimes white matter lesions are expression of a genetic disease. While many inherited leukoencephalopathies fall in the child neurologist's interest, others may have a delayed or even a typical onset in the middle or old age. This field is rapidly growing and, in the last few years, many new inherited white matter diseases have been described and genetically defined. A non-delayed recognition of middle and old age inherited leukoencephalopathies appears important to avoid unnecessary tests and therapies in the patient and to possibly anticipate the diagnosis in relatives. The aim of this review is to provide a guide to direct the diagnostic process when facing a patient with a suspicion of an inherited form of leukoencephalopathy and with clinical onset in middle or old age. Based on a MEDLINE search from 1990 to 2013, we identified 24 middle and old age onset inherited leukoencephalopathies and reviewed in this relation the most recent findings focusing on their differential diagnosis. We provide summary tables to use as a check list of clinical and neuroimaging findings that are most commonly associated with these forms of leukoencephalopathies. When present, we reported specific characteristics of single diseases. Several genetic diseases may be suspected in patients with middle or old age and white matter abnormalities. In only few instances, pathognomonic clinical or associated neuroimaging features help identifying a specific disease. Therefore, a comprehensive knowledge of the characteristics of these inherited white matter diseases appears important to improve the diagnostic work-up, optimize the choice of genetic tests, increase the number of diagnosed patients, and stimulate the research interest in this field.

The assessment of beta amyloid, tau protein and cystatin C in the cerebrospinal fluid: laboratory markers of neurodegenerative diseases

To assess the role of tau protein, beta-amyloid(1-42) and cystatin C in the diagnostics of Alzheimer dementia (AD) and other neurodegenerative diseases (ND) by comparing to the control groups (CG). The levels of tau protein, beta-amyloid(1-42) and cystatin C were assessed in the set of 69 patients (AD + ND, 33 males, 36 females, aged 22-90, mean 60.5 + 16.1 years), and in a control group of 69 subjects without the affection of the central nervous system (CGAD + CGND, 33 males, 36 females, aged 20-91, mean 60.5 + 16.0 years). Statistically significant increased tau protein levels (P = 0.0001) and index tau/beta-amyloid(1-42) levels (P = 0.0002) were shown in the group of AD patients, compared to the group of ND patients. One-way ANOVA analysis with Bonferonni post hoc test did not show any significant differences of the cystatin C values between any of the compared groups. ROC analysis showed at least one tie between the positive actual state group (AD) and the negative actual state group (ND) by CSF cystatin C and at least one tie between the positive actual state group and the negative actual state group by CSF tau protein. Our study confirmed previously reported results only in part. While tau protein seems to be quite a reliable marker of AD, the role of beta-amyloid(1-42) and cystatin C in AD diagnosis remains at least questionable.

A drastic reduction in the life span of cystatin C L68Q carriers due to life-style changes during the last two centuries

Hereditary cystatin C amyloid angiopathy (HCCAA) is an autosomal dominant disease with high penetrance, manifest by brain hemorrhages in young normotensive adults. In Iceland, this condition is caused by the L68Q mutation in the cystatin C gene, with contemporary carriers reaching an average age of only 30 years. Here, we report, based both on linkage disequilibrium and genealogical evidence, that all known copies of this mutation derive from a common ancestor born roughly 18 generations ago. Intriguingly, the genealogies reveal that obligate L68Q carriers born 1825 to 1900 experienced a drastic reduction in life span, from 65 years to the present-day average. At the same time, a parent-of-origin effect emerged, whereby maternal inheritance of the mutation was associated with a 9 year reduction in life span relative to paternal inheritance. As these trends can be observed in several different extended families, many generations after the mutational event, it seems likely that some environmental factor is responsible, perhaps linked to radical changes in the life-style of Icelanders during this period. A mutation with such radically different phenotypic effects in reaction to normal variation in human life-style not only opens the possibility of preventive strategies for HCCAA, but it may also provide novel insights into the complex relationship between genotype and environment in human disease.

Hereditary cystatin C amyloid angiopathy: genetic, clinical, and pathological aspects

Hereditary cystatin C amyloid angiopathy (HCCAA) is a rare, fatal amyloid disease in young people in Iceland caused by a mutation in cystatin C, which is an inhibitor of several cysteine proteinases, such as cathepsins S, B, and K. The same mutation in cystatin C, L68Q, has been found in all patients examined so far pointing to a common founder. Most of the families can be traced to a region in the northwest of Iceland, around Breidafjordur bay. Mutated cystatin C forms amyloid, predominantly in brain arteries and arterioles, but also to a lesser degree in tissues outside the central nervous system such as skin, lymph nodes, testis, spleen, submandibular salivary glands, and adrenal cortex. The amyloid deposition in the vessel walls causes thickening of the walls leading to occlusion or rupture and resulting in brain hemorrhage. Although the amyloid can be detected outside the brain, the clinical manifestation is restricted to the brain, and usually consists of repeated hemorrhages leading to paralysis. Sometimes the initial signs of hemorrhage are dementia and personality changes.

Late-onset neuroaxonal leucoencephalopathy with spheroids and vascular amyloid

A 54-year-old man with a 7-year history of early-onset, slowly progressive dementia and motor impairment characterised by diffuse, non-enhancing white matter signal change. Neuropathologic examination demonstrated subcortical pigmentation with neuroaxonal spheroid formation, profound axonal loss with secondary myelin degeneration and widespread betaA4 immunopositivity involving meningeal and subcortical vessels. There was relative sparing of brain stem and cerebellar white matter. The neocortex was normal. The appearances expand the spectrum of adult-onset neuroaxonal leucoencephalopathy with spheroids (NALS) and demonstrate that vascular betaA4 amyloid plays a key role in the white matter pathology of NALS.

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 of L68Q-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 of L68Q- 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 precipitating aggregates.

Inborn errors of metabolism: a clinical overview

CONTEXT

Inborn errors of metabolism cause hereditary metabolic diseases (HMD) and classically they result from the lack of activity of one or more specific enzymes or defects in the transportation of proteins.

OBJECTIVES

A clinical review of inborn errors of metabolism (IEM) to give a practical approach to the physician with figures and tables to help in understanding the more common groups of these disorders.

DATA SOURCE

A systematic review of the clinical and biochemical basis of IEM in the literature, especially considering the last ten years and a classic textbook (Scriver CR et al, 1995).

SELECTION OF STUDIES

A selection of 108 references about IEM by experts in the subject was made. Clinical cases are presented with the peculiar symptoms of various diseases.

DATA SYNTHESIS

IEM are frequently misdiagnosed because the general practitioner, or pediatrician in the neonatal or intensive care units, does not think about this diagnosis until the more common cause have been ruled out. This review includes inheritance patterns and clinical and laboratory findings of the more common IEM diseases within a clinical classification that give a general idea about these disorders. A summary of treatment types for metabolic inherited diseases is given.

CONCLUSIONS

IEM are not rare diseases, unlike previous thinking about them, and IEM patients form part of the clientele in emergency rooms at general hospitals and in intensive care units. They are also to be found in neurological, pediatric, obstetrics, surgical and psychiatric clinics seeking diagnoses, prognoses and therapeutic or supportive treatment.

Amyloid angiopathy in a Volga German family with Alzheimer's disease and a presenilin-2 mutation (N141I)

We report the neuropathological features in 6 members of a Volga German family with autosomal dominant Alzheimer's disease linked to chromosome 1 who had a presenilin-2 mutation (N141I). The most significant feature in this family was the presence of severe or moderately severe amyloid angiopathy in five family members with clinical dementia. The index case with the presenilin-2 mutation had late-onset dementia at age 73 years, died of an acute intracerebral hemorrhage, and pathologically showed severe amyloid angiopathy but only rare neuritic senile plaques and neurofibrillary tangles. That she was apolipoprotein E epsilon2/3 heterozygous suggests that the epsilon2 allele may have exerted a selective protective effect resulting in late onset relatively mild Alzheimer's disease despite severe amyloid angiopathy. This family emphasizes the need for more investigation into the role of presenilin mutations in amyloid deposition, especially in the cerebral vasculature, and the role of these changes in clinical dementia.