Genome-wide allelic methylation analysis reveals disease-specific susceptibility to multiple methylation defects in imprinting syndromes.

Genomic imprinting is the parent-of-origin-specific allelic transcriptional silencing observed in mammals, which is governed by DNA methylation established in the gametes and maintained throughout the development. The frequency and extent of epimutations associated with the nine reported imprinting syndromes varies because it is evident that aberrant preimplantation maintenance of imprinted differentially methylated regions (DMRs) may affect multiple loci. Using a custom Illumina GoldenGate array targeting 27 imprinted DMRs, we profiled allelic methylation in 65 imprinting defect patients.

Defining the phenotype in an autosomal recessive cutis laxa syndrome with a combined congenital defect of glycosylation.

Autosomal recessive cutis laxa is a genetically heterogeneous condition. Its molecular basis is largely unknown. Recently, a combined disorder of N- and O-linked glycosylation was described in children with congenital cutis laxa in association with severe central nervous system involvement, brain migration defects, seizures and hearing loss.

Maternal UPD 20 in an infant from a pregnancy with mosaic trisomy 20.

Maternal uniparental disomy (UPD) 20 was found in a 35-month-old girl, the product of a pregnancy complicated by a prenatal diagnosis of mosaic trisomy 20. Phenotypic abnormalities included pre- and postnatal growth failure, microcephaly, minor dysmorphic features and psychomotor developmental delay. Chromosomal analysis on cord blood revealed only a normal 46,XX karyotype.

Clinical implications of atypical chromosome abnormalities diagnosed prenatally.

Objective: To determine the frequency of atypical aneuploidy resulting from prenatal testing and assess the implications of these diagnoses on prenatal decision making.

Methods: We reviewed all amniotic fluid and chorionic villus samples obtained between January 1994 and September 1997 and grouped the abnormal cases into typical or atypical subcategories. This distinction was based upon whether the diagnosis provided a straightforward range of prognoses or an ambiguous clinical implication.