Understanding XDP through imaging,pathology,and genetics

The X-linked dystonia-parkinsonism (XDP) is a severe progressive, adult-onset X-linked endemic disorder in Filipinos, which is characterized by dystonic movements that start in the third of fourth decade, and replaced by parkinsonism beyond the 10th year of illness. Understanding the pathophysiology of XDP and development of rational therapies will depend on observations from imaging pathological and genetic studies. In this paper we summarize the results of these studies on patients with XDP. The cranial magnetic resonance imaging shows hy-perintense putaminal rim in both dystonic and parkinsonian stages, and atrophy of the caudate head or putamen in the parkinsonian stage. Neuropathological findings show atrophy of the caudate nucleus and putamen, with mild to severe neuronal loss and gliosis. In the neostriatum, the dystonic phase of XDP shows the involvement of striosomes and matrix sparing, while the later, i.e., p[arkinsonian phase, shows matrix involvement as well. In the dystonic phase, the loss of striosomal inhibitory projections lead to disinhibition of nigral dopaminergic neurons, perhaps resulting in a hyperkinetic state; while in the parkinsonian phase, severe and critical reduction of matrix-based projection may result in extranigral parkinsonism. Genetic sequencing of the XDP critical region in Xq13.1 has revealed an SVA retronsposon insertion in an intron of TAF1. This may reduce neuron-specific expression of the TAF1 isoform in the caudade nucleus, and subsequently interfere with the transcription of many neuronal genes, including DRD2. Findings from imaging, pahtology, and genetics studies are gradually shedding light on the pathophysiology of XDP, which hopefully will lead to mare rational and directed therapies.

The unique phenomenology of sex-linked dystonia parkinsonism (XDP, DYT3, "Lubag")

Sex-linked dystonia parkinsonism (XDP, DYT3, "Lubag") is an adult-onset, progressive, debilitating movement disorder first described in Filipino males from Panay Island in 1975. XDP manifests predominantly as torsion dystonia, later combined with or sometimes replaced with parkinsonism. Within the Island of Panay, the preva-lence rate is highest in the province of Capiz, where 1:4000 men suffer from the disorder. There is a high degree of penetrance and generalization. While women often serve as carriers, XDP is not limited to men. An updated XDP Philippine registry (as of January 2010) has identified 505 cases, with 500 males and 5 females. While some report that females may carry a milder form of the disorder, in our experience, both sexes generally follow a similar progressive clinical course.

Understanding XDP through imaging, pathology, and genetics.

The X-linked dystonia-parkinsonism (XDP) is a severe, progressive, adult-onset, X-linked endemic disorder in Filipinos, which is characterized by dystonic movements that start in the third or fourth decade, and replaced by parkinsonism beyond the 10th year of illness. Understanding the pathophysiology of XDP and development of rational therapies will depend on observations from imaging, pathological, and genetic studies. In this paper we summarize the results of these studies on patients with XDP. The cranial magnetic resonance imaging shows hyperintense putaminal rim in both dystonic and parkinsonian stages, and atrophy of the caudate head or putamen in the parkinsonian stage. Neuropathological findings show atrophy of the caudate nucleus and putamen, with mild to severe neuronal loss and gliosis. In the neostriatum, the dystonic phase of XDP shows the involvement of striosomes and matrix sparing, while the later, i.e., parkinsonian phase, shows matrix involvement as well. In the dystonic phase, the loss of striosomal inhibitory projections lead to disinhibition of nigral dopaminergic neurons, perhaps resulting in a hyperkinetic state; while in the parkinsonian phase, severe and critical reduction of matrix-based projection may result in extranigral parkinsonism. Genetic sequencing of the XDP critical region in Xq13.1 has revealed an SVA retrotransposon insertion in an intron of TAF1. This may reduce neuron-specific expression of the TAF1 isoform in the caudate nucleus, and subsequently interfere with the transcription of many neuronal genes, including DRD2. Findings from imaging, pathology, and genetics studies are gradually shedding light on the pathophysiology of XDP, which hopefully will lead to more rational and directed therapies.

The unique phenomenology of sex-linked dystonia parkinsonism (XDP, DYT3, "Lubag").

Sex-linked dystonia parkinsonism (XDP, DYT3, "Lubag") is an adult-onset, progressive, debilitating movement disorder first described in Filipino males from Panay Islands in 1975. XDP manifests predominantly as torsion dystonia, later combined with or sometimes replaced with parkinsonism. Within the Island of Panay, the prevalence rate is highest in the province of Capiz, where 1:4000 men suffer from the disorder. There is a high degree of penetrance and generalization. While women often serve as carriers, XDP is not limited to men. An updated XDP Philippine registry (as of January 2010) has identified 505 cases, with 500 males and 5 females. While some report that females may carry a milder form of the disorder, in our experience, both sexes generally follow a similar progressive clinical course.

Functional anatomy of the basal ganglia in X-linked recessive dystonia-parkinsonism.

Dystonia is a neurological syndrome characterized by sustained muscle contractions that produce repetitive twisting movements or abnormal postures. X-linked recessive dystonia parkinsonism (XDP; DYT3; Lubag) is an adult-onset disorder that manifests severe and progressive dystonia with a high frequency of generalization. In search for the anatomical basis for dystonia, we performed postmortem analyses of the functional anatomy of the basal ganglia based on the striatal compartments (ie, the striosomes and the matrix compartment) in XDP. Here, we provide anatomopathological evidence that, in the XDP neostriatum, the matrix compartment is relatively spared in a unique fashion, whereas the striosomes are severely depleted. We also document that there is a differential loss of striatal neuron subclasses in XDP. In view of the three-pathway basal ganglia model, we postulate that the disproportionate involvement of neostriatal compartments and their efferent projections may underlie the manifestation of dystonia in patients with XDP. This study is the first to our knowledge to show specific basal ganglia pathology that could explain the genesis of dystonia in human heredodegenerative movement disorders, suggesting that dystonia may result from an imbalance in the activity between the striosomal and matrix-based pathways.