RESUMO
The association of maternal uniparental disomy for chromosome 7 and postnatal growth failure has been reported in four cases and suggests the presence of genomic imprinting of one or more growth related genes on chromosome 7. However, in the reported cases, the possibility of homozygosity for a recessive mutation could not be excluded as the cause of the growth failure as in all cases isodisomy rather than heterodisomy for chromosome 7 was present. We report a case of prenatal and postnatal growth retardation associated with a prenatal diagnosis of mosaicism for trisomy 7 confined to the placenta. DNA typing of polymorphic markers on chromosome 7 has established that the zygote originated as a trisomy 7 with two maternal and one paternal chromosomes 7 with subsequent loss of the paternal chromosome resulting in a disomic child with maternal heterodisomy for chromosome 7. The growth failure seen in this child with heterodisomy 7 lends strong support to the hypothesis of imprinted gene(s) on chromosome 7.
Assuntos
Aberrações Cromossômicas/genética , Cromossomos Humanos Par 7/genética , Retardo do Crescimento Fetal/genética , Impressão Genômica , Transtornos do Crescimento/genética , Adulto , Amostra da Vilosidade Coriônica , Aberrações Cromossômicas/embriologia , Transtornos Cromossômicos , Feminino , Retardo do Crescimento Fetal/diagnóstico por imagem , Humanos , Recém-Nascido , Cariotipagem , Mosaicismo , Não Disjunção Genética , Placenta/ultraestrutura , Gravidez , Trissomia , Ultrassonografia Pré-Natal , Zigoto/ultraestruturaRESUMO
Two distinct phenotypes of triploid fetuses have been previously described and a correlation with parental origin of the triploidy has been suggested. We have studied the parental origin of the extra haploid set of chromosomes in nine triploid fetuses using analysis of DNA polymorphisms at a variety of loci. Maternal origin of the triploidy (digyny) was demonstrated in six fetuses with type II phenotype, paternal origin (diandry) in two cases with type I phenotype, and nonpaternity in one case. The predominance of digynic triploids in our study contrasts with the results reported in previous studies in which, through analysis of cytogenetic polymorphisms, paternal origin was found to account for the majority of triploid conceptuses. This difference may be accounted for by a combination of factors--the different methods of parental assignment used and analysis of a different subset of triploid conceptuses. The correlation between the observed phenotypes and the parental origin of triploidy may represent another example of imprinting in human development.
Assuntos
Anormalidades Múltiplas/genética , Doenças Fetais/genética , Regulação da Expressão Gênica , Pais , Poliploidia , Feminino , Doenças Fetais/classificação , Retardo do Crescimento Fetal/genética , Humanos , Mola Hidatiforme/genética , Masculino , Placenta/anormalidades , Polimorfismo de Fragmento de Restrição , Gravidez , Fatores Sexuais , Neoplasias Uterinas/genéticaRESUMO
A Raji cell microplate-ELISA method has been devised for the detection and quantitation of putative immune complexes present in human sera. The Raji cells immobilized with glutaraldehyde (final concentration 0.67%) were conveniently utilized in the solid phase system. The specific binding of AHG diluted in PBS (without complement) increased linearly in the range of 0.1 to 5 micrograms. The purified human IgG showed some low-affinity binding which was 7-to 14-fold lower than the binding of AHG. The circulating immune complexes positive sera were found to have values above the mean of 11.95 +/- 4.09 micrograms/ml AHG equivalent for normal human sera (n = 72). The method is sensitive, reproducible and it can be performed with simplicity and rapidity.