Monochorionic, diamniotic twins discordant for acardia are reported. A 775 g acardius was dead, generally hydropic and severely malformed, while the other twin with a weight of 1314 g was phenotypically normal. Both t...Monochorionic, diamniotic twins discordant for acardia are reported. A 775 g acardius was dead, generally hydropic and severely malformed, while the other twin with a weight of 1314 g was phenotypically normal. Both twins had a normal 46 XX karyotype. Genotyping at 24 autosomal polymorphic loci revealed that the twins were identical (monozygotic) and ruled out uniparental disomy for chromosome 2. X inactiva tion studies showed a skewed pattern in the acardiac twin and a normal random pattern in the co twin, suggesting that the underdevelopment of the acardiac twin may have reflected the small number of original cells that were separated from the inner cell mass.展开更多
Fragile X tremor/ataxia syndrome (FXTAS) is a recently described condition co nsisting of tremor, ataxia, parkinsonism, and executive dysfunction, presenting predominantly in male carriers of a fragile X mental retard...Fragile X tremor/ataxia syndrome (FXTAS) is a recently described condition co nsisting of tremor, ataxia, parkinsonism, and executive dysfunction, presenting predominantly in male carriers of a fragile X mental retardation 1 premutation. In this report, we present premutation carrier sisters in whom severity of clini cal signs correlated with a molecular pattern of X-inactivation favoring highe r expression of the premutation allele. In these women with a common genetic bac kground, we suggest that symptom severity may be dictated by X-inactivation, a nd thus a higher percentage of cells producing the premutation-containing mRNA result in increased toxicity and disease.展开更多
文摘Monochorionic, diamniotic twins discordant for acardia are reported. A 775 g acardius was dead, generally hydropic and severely malformed, while the other twin with a weight of 1314 g was phenotypically normal. Both twins had a normal 46 XX karyotype. Genotyping at 24 autosomal polymorphic loci revealed that the twins were identical (monozygotic) and ruled out uniparental disomy for chromosome 2. X inactiva tion studies showed a skewed pattern in the acardiac twin and a normal random pattern in the co twin, suggesting that the underdevelopment of the acardiac twin may have reflected the small number of original cells that were separated from the inner cell mass.
文摘Fragile X tremor/ataxia syndrome (FXTAS) is a recently described condition co nsisting of tremor, ataxia, parkinsonism, and executive dysfunction, presenting predominantly in male carriers of a fragile X mental retardation 1 premutation. In this report, we present premutation carrier sisters in whom severity of clini cal signs correlated with a molecular pattern of X-inactivation favoring highe r expression of the premutation allele. In these women with a common genetic bac kground, we suggest that symptom severity may be dictated by X-inactivation, a nd thus a higher percentage of cells producing the premutation-containing mRNA result in increased toxicity and disease.
