Huntington disease-like 2: the first patient with apparent European ancestry.

Huntington disease-like 2 (HDL2) is a rare autosomal dominant disorder of the nervous system, apparently indistinguishable from Huntington disease (HD). HDL2 is caused by the expansion above 40 CTG/CAG repeats, in a variably spliced exon of the junctophilin-3 gene, on chromosome 16q24.3. All patients described so far have been of African ancestry. A clinical evaluation, including the Unified Huntington's Disease Rating Scale, and brain Magnetic resonance imaging were achieved in a 48-year-old Brazilian man of apparent European extraction, and presenting a picture very suggestive of HD. Gene mutation analysis (HD, HDL1, HDL2, dentatorubralpallidoluysian atrophy and spinocerebellar ataxia 17) was performed. After exclusion of the HD mutation and other HDL disorders, we identified an expansion of 47 CTG/CAG at the HDL2 locus. To clarify the origin of the mutation and estimate the patient's ancestry, we performed haplotype studies and used the insertion/deletion polymorphisms method. Despite the fact that this patient had an estimated likelihood of 97.4% of being of European ancestry, the haplotype containing the expanded allele has been found only in Africans. Thus, this is the first HDL2 case reported in a patient with an apparent European ancestry, although bearing an African HDL2 haplotype. This work stresses the importance of performing the diagnosis of HDL2 in HD-like patients of various ethnicities, and particularly in highly mixed populations.

Report of a patient with a trisomy of chromosome region 20q11.2-->20q12 and characterization with FISH.

We report on a 16-month-old boy presenting with psychomotor retardation, craniofacial anomalies and severe vision deficit. Analysis of GTG-banded chromosomes showed that the patient had extra chromosomal material in the long arm of one chromosome 20. This chromosome aberration was further characterized with FISH using a chromosome 20 specific paint and band-specific probes. A partial trisomy 20q was shown to be present, the karyotype being 46, XY, dup (20) (q11.2q12). The cytogenetic and clinical findings are compared with cases previously reported in the literature.