Postzygotic mosaicism in basal cell naevus syndrome.

Basal cell naevus syndrome (BCNS) is an autosomal dominant disorder most commonly caused by a germline mutation in the Drosophila homologue of patched-1 gene (PTCH1). Here we describe a patient with clinical signs of BCNS, caused by postzygotic mosaicism of a PTCH1 mutation. We performed restriction fragment length polymorphism analysis and Droplet Digital polymerase chain reaction to determine the degree of mosaicism in different tissues of this patient. Our case shows that a relatively low-grade mosaicism can lead to clinical signs reminiscent of those caused by a germline mutation. This finding has important implications for genetic counselling and therefore is pivotal to recognize for dermatologists, as well as for clinical geneticists and clinical laboratory geneticists.

A genetically controlled hippocampal transmitter system regulating exploratory behavior in mice.

Male C57BL/6 and DBA/2 mice were intrahippocampally microinjected with muscimol (0.5 microgram), given 15 min prior to individual 20-min exploration tests in a novel environment, and compared to saline controls. The GABA agonist reduced various exploratory acts and locomotor activity in strain C57BL/6 and increased the scores in DBA/2. In conjunction with similar opposite effects previously found with intra-hippocampal methylscopolamine and naloxone, these findings suggest that the opioid modulation of the hippocampal cholinergic mechanism which facilitates behavioral responses to novelty in mice is effectuated indirectly through an inhibitory GABAergic system. The functioning of these regulatory systems appears to depend on genotype.