Alteration of ganglioside biosynthesis responsible for complex hereditary spastic paraplegia.

Hereditary spastic paraplegias (HSPs) form a heterogeneous group of neurological disorders. A whole-genome linkage mapping effort was made with three HSP-affected families from Spain, Portugal, and Tunisia and it allowed us to reduce the SPG26 locus interval from 34 to 9 Mb. Subsequently, a targeted capture was made to sequence the entire exome of affected individuals from these three families, as well as from two additional autosomal-recessive HSP-affected families of German and Brazilian origins. Five homozygous truncating (n = 3) and missense (n = 2) mutations were identified in B4GALNT1. After this finding, we analyzed the entire coding region of this gene in 65 additional cases, and three mutations were identified in two subjects. All mutated cases presented an early-onset spastic paraplegia, with frequent intellectual disability, cerebellar ataxia, and peripheral neuropathy as well as cortical atrophy and white matter hyperintensities on brain imaging. B4GALNT1 encodes ß-1,4-N-acetyl-galactosaminyl transferase 1 (B4GALNT1), involved in ganglioside biosynthesis. These findings confirm the increasing interest of lipid metabolism in HSPs. Interestingly, although the catabolism of gangliosides is implicated in a variety of neurological diseases, SPG26 is only the second human disease involving defects of their biosynthesis.

Clinical and genetic analysis of 29 Brazilian patients with Huntington's disease-like phenotype.

Huntington's disease (HD) is a neurodegenerative disorder characterized by chorea, behavioral disturbances and dementia, caused by a pathological expansion of the CAG trinucleotide in the HTT gene. Several patients have been recognized with the typical HD phenotype without the expected mutation. The objective of this study was to assess the occurrence of diseases such as Huntington's disease-like 2 (HDL2), spinocerebellar ataxia (SCA) 1, SCA2, SCA3, SCA7, dentatorubral-pallidoluysian atrophy (DRPLA) and chorea-acanthocytosis (ChAc) among 29 Brazilian patients with a HD-like phenotype. In the group analyzed, we found 3 patients with HDL2 and 2 patients with ChAc. The diagnosis was not reached in 79.3% of the patients. HDL2 was the main cause of the HD-like phenotype in the group analyzed, and is attributable to the African ancestry of this population. However, the etiology of the disease remains undetermined in the majority of the HD negative patients with HD-like phenotype.

Clinical and genetic analysis of 29 Brazilian patients with Huntington's disease-like phenotype / Análise clínica e genética em 29 pacientes Brasileiros com fenótipo doença de Huntington-símile

Huntington's disease (HD) is a neurodegenerative disorder characterized by chorea, behavioral disturbances and dementia, caused by a pathological expansion of the CAG trinucleotide in the HTT gene. Several patients have been recognized with the typical HD phenotype without the expected mutation. The objective of this study was to assess the occurrence of diseases such as Huntington's disease-like 2 (HDL2), spinocerebellar ataxia (SCA) 1, SCA2, SCA3, SCA7, dentatorubral-pallidoluysian atrophy (DRPLA) and chorea-acanthocytosis (ChAc) among 29 Brazilian patients with a HD-like phenotype. In the group analyzed, we found 3 patients with HDL2 and 2 patients with ChAc. The diagnosis was not reached in 79.3 percent of the patients. HDL2 was the main cause of the HD-like phenotype in the group analyzed, and is attributable to the African ancestry of this population. However, the etiology of the disease remains undetermined in the majority of the HD negative patients with HD-like phenotype.

A doença de Huntington (DH) é uma doença neurodegenerativa caracterizada por coréia, alterações comportamentais e demência, causada por uma expansão patológica do trinucleotídeo CAG no gene HTT. Vários pacientes têm sido descritos com o fenótipo típico para a DH porém sem a mutação esperada. O objetivo deste estudo foi avaliar a ocorrência de doenças como doença de Huntington-símile 2 (DHS-2), ataxias espinocerebelares tipo 1, 2, 3 e 17, atrofia dentatorubral-palidoluisiana e coreo-acantocitose (CAc) entre 29 pacientes brasileiros com fenótipo doença de Huntington-símile. No grupo analisado, encontramos 3 pacientes com DHS-2 e 2 pacientes com CAc. O diagnóstico permaneceu obscuro em 79,3 por cento dos pacientes. DHS-2 foi a principal causa do fenótipo DH-símile no grupo analisado, provavelmente devido a ancestralidade africana na população brasileira. Entretanto, a etiologia permaneceu indeterminada na maioria dos pacientes avaliados.

Huntington's disease-like 2 in Brazil--report of 4 patients.

Huntington's disease-like 2 (HDL2) is a neurodegenerative disorder found in people of African ancestry with clinical, radiological, and neuropathological manifestations similar to Huntington's disease (HD). HDL2 is caused by a pathological expansion of CAG/CTG triplets in exon 2A of the JPH3 gene. We describe four cases of HDL2 from four unrelated families, and discuss their clinical findings. HDL2 should be considered in every patient with an HD-like phenotype who tests negative for the HD mutation, even if African ancestry is not immediately apparent.

The PSP-associated MAPT H1 subhaplotype in Guadeloupean atypical parkinsonism.

The aim of this study was to determine whether the H1 subhaplotype in MAPT associated with progressive supranuclear palsy (PSP) in Caucasians confers risk for PSP-like atypical parkinsonism in Guadeloupe, a tauopathy. Guadeloupean controls and patients with atypical and idiopathic parkinsonism and ethnically and age-matched controls were genotyped for H1 and H2 alleles, then for the H1 subhaplotype associated with PSP in Caucasians, using previously described haplotype-tagging single nucleotide polymorphisms (Ht-SNPs) in linkage disequilibrium at the MAPT locus. Most Guadeloupean controls and patients were homozygous for the H1 allele; only 5% were heterozygous for the H2 allele, consistent with the European contribution to the racial admixture in Guadeloupe, but equivalent to the frequency found in Caucasian PSP patients. The frequencies of the Ht-SNPs used to determine the PSP-associated H1 subhaplotype in both Guadeloupean controls and parkinsonians were similar, indicating that the H1 subhaplotype associated with PSP in Caucasians was not a risk factor for PSP-like atypical parkinsonism in Guadeloupe. Interestingly, they were also similar to the frequencies in Caucasian PSP patients. The major H1 subhaplotype in Guadeloupe, determined by analysis of linkage desequibrium, differed from the major Caucasian subhaplotype, but corresponded to minor alleles previously described.

A genetic cluster of early onset Parkinson's disease in a Colombian population.

We previously identified in two families with early onset Parkinson's Disease (PD) from the isolated population of Antioquia (Colombia), a parkin Cys212Tyr substitution caused by a G736A mutation. This mutation was subsequently observed in a Spanish family, suggesting that it could have been taken to Antioquia by Spanish immigrants. Here we screened for the G736A mutation in additional Antioquian early onset PD cases and used haplotype analysis to investigate the relationship between Spanish and Antioquian G736A chromosomes. We confirmed the occurrence of an extensive founder effect in Antioquia. Thirteen individuals (10 homozygotes) from seven nuclear families were identified with the G736A mutation. Genealogical investigations demonstrated the existence of shared ancestors between six of these families four to five generations ago and no evidence of Spanish ancestry during this period. A second parkin mutation (a duplication of exon 3), was detected in the three G736A heterozygote carriers. Haplotype data exclude a recent common ancestry between the Spanish and Antioquian patients studied here and is consistent with the introduction of the G736A mutation in Antioquia during early colonial times (about 16 generations ago).

Guadeloupean parkinsonism: a cluster of progressive supranuclear palsy-like tauopathy.

An unusually high frequency of atypical Parkinson syndrome has been delineated over the last 5 years in the French West Indies. Postural instability with early falls, prominent frontal lobe dysfunction and pseudo-bulbar palsy were common and three-quarters of the patients were L-dopa unresponsive. One-third of all patients seen had probable progressive supranuclear palsy (PSP). This new focus of atypical parkinsonism is reminiscent of the one described in Guam and may be linked to exposure to tropical plants containing mitochondrial complex I inhibitors (quinolines, acetogenins, rotenoids). Two hundred and twenty consecutive patients with Parkinson's syndrome seen by the neurology service at Pointe à Pitre, Guadeloupe University Hospital were studied. Currently accepted operational clinical criteria for Parkinson's syndromes were applied. The pathological findings of three patients who came to autopsy are reported. Fifty-eight patients had probable PSP, 96 had undetermined parkinsonism and 50 had Parkinson's disease, 15 had amyotrophic lateral sclerosis with parkinsonism and one had probable multiple system atrophy. All three PSP patients in whom post-mortem study was performed had early postural instability, gaze palsy and parkinsonian symptoms, followed by a frontolimbic dementia and corticobulbar signs. Neuropathological examination showed an accumulation of tau proteins, predominating in the midbrain. There was an exceptionally large accumulation of neuropil threads in Case 1. Biochemical studies detected a major doublet of pathological tau at 64 and 69 kDa in brain tissue homogenates. All cases were homozygous for the H1 tau haplotype, but no mutation of the tau gene was observed. Clinical, neuropathological and biochemical features were compatible with the diagnosis of PSP, although some unusual pathological features were noted in Case 1. A cluster of cases presenting with atypical parkinsonism is reported. Guadeloupean parkinsonism may prove to be a tauopathy identical or closely related to PSP.