Beckwith–Wiedemann syndrome (BWS) is one of the most prevalent congenital disorders predominantly caused by epigenetic alterations. Here we present an extensive case study of a monozygotic monochorionic male twin pair discordant for BWS. Our analysis allows to correlate BWS symptoms, like a protruding tongue, indented ears and transient neonatal hypoglycaemia, to an abnormal methylation at the KvDMR1. DNAs extracted from peripheral blood, skin fibroblasts, saliva and buccal swab of both twins, their sister and parents were analysed at 11 differentially methylated regions (DMRs) including all four relevant DMRs of the BWS region. The KvDMR1 was exclusively found to be hypomethylated in all cell types of the affected BWS twin, while the unaffected twin and the relatives showed normal methylation in fibroblasts, buccal swab and saliva DNA. Interestingly, the twins share a common blood-specific hypomethylation phenotype most probably caused by a feto-fetal transfusion between both twins. Because microsatellite analysis furthermore revealed a normal biparental karyotype for chromosome 11, our results point to an exclusive correlation of the observed BWS symptoms to locally restricted epimutations at the KvDMR1 of the maternal chromosome.

This study examines the relationship between episodic memory and hippocampal volume (magnetic resonance imaging [MRI] volumetry) in preterm children with uncomplicated neonatal courses (<34 weeks of gestation, birth weight <2,000 g) and controls (7-11 years). To examine episodic memory performance and retrieval processes, neuropsychological tests and a recognition experiment were used. Although preterm children showed reduced hippocampal volumes relative to controls by 12%, episodic memory accuracy was not reduced. However, only in controls hippocampal volume correlated with some measures of episodic memory. Together, behavioral and MRI results indicate a minor functional specificity of the hippocampus regarding episodic memory functions in preterm children.

Infant care often is carried out under stressful circumstances. Little is known about differences in caretaking motivation between men and women under stress. In the present study, stress was induced in 40 participants (21 women, 19 men) by means of the cold pressor stress test, 40 (22 women, 18 men) serving as controls. Participants then rated their urge to care for newborn infants shown on 20 short video clips. The infants in the videos were either crying (N=10) or were showing typical neonatal facial movements (N=10). Skin conductance was obtained while participants viewed the videos and salivary cortisol was measured to capture stress responses. We found sex differences in caretaking motivation, such that stress led to decreased caretaking motivation in men but not in women. Furthermore, stressed men elicited a stronger skin conductance change while viewing infant videos than stressed women. These findings provide further evidence for differential stress reactions in men and women and may have crucial implications for parental care.

Prematurity may cause hippocampal compromise. Therefore, hippocampus-dependent memory processes (recollection-based retrieval) may be more impaired than hippocampus-independent processes (familiarity-based retrieval). The memory of 18 children born preterm with reduced hippocampal volumes, without neonatal complications (weeks of gestation < 34, weight < 1,600 g), and 15 controls (8-10 years) was tested using an item recognition task. While groups were equal in memory performance, dissociation was found: The event-related potential (ERP) correlate of familiarity was intact in the preterm group, whereas the correlate of recollection was attenuated. A follow-up experiment ruled out that this was due to general cognitive deficits. Furthermore, gestational age correlated with the ERP index of recollection. Thus, recognition memory in preterm children may be characterized by a compensation of attenuated recollection by familiarity.

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