Sotos syndrome (SoS) is an autosomal dominant overgrowth syndrome with characteristic craniofacial dysmorphic features and various degrees of mental retardation. We previously showed that haploinsufficiency of the NSD1 gene is the major cause of SoS, and submicroscopic deletions at 5q35, including NSD1, were found in about a half (20/42) of our patients examined. Since the first report, an additional 70 SoS cases consisting of 53 Japanese and 17 non-Japanese have been analyzed. We found 50 microdeletions (45%) and 16 point mutations (14%) among all the 112 cases. A large difference in the frequency of microdeletions between Japanese and non-Japanese patients was noted: 49 (52%) of the 95 Japanese patients and only one (6%) of the 17 non-Japanese had microdeletions. A sequence-based physical map was constructed to characterize the microdeletions. Most of the microdeletions were confirmed to be identical by FISH analysis. We identified highly homologous sequences, i.e., possible low copy repeats (LCRs), in regions flanking proximal and distal breakpoints of the common deletion, This suggests that LCRs may mediate the deletion. Such LCRs seem to be present in different populations. Thus the different frequency of microdeletions between Japanese and non-Japanese cases in our study may have been caused by patient-selection bias.

Rotavirus antigenemia is frequently observed in a patient's serum during the acute phase, and viral antigen levels change dramatically during the acute phase of the illness. Because patients with fever had higher rotavirus antigen levels, antigenemia severity might contribute to fever. The host immune response plays an important role in controlling antigenemia levels.

Twenty-one infants who had virologically confirmed exanthem subitum and central nervous system (CNS) complications were studied to elucidate the clinical features, laboratory and virological findings, and outcome. The primary infection with human herpesvirus 6 was confirmed by isolation of the virus from blood, a significant rise in the antibody titers to the virus, or both. All convulsive seizures (15 generalized and 6 focal) occurred during the pre-eruptive stage of exanthem subitum. Four infants with encephalitis/encephalopathy had more severe clinical features with abnormalities demonstrated on electroencephalograms and cerebral computed tomograms. All infants except those with encephalitis/encephalopathy recovered without any sequelae. One infant with encephalitis/encephalopathy developed epilepsy and another one died. Human herpesvirus 6 DNA amplified by the nested polymerase chain reaction method was detected in the cerebrospinal fluid of 6 infants, including 3 with encephalitis/encephalopathy, of 11 patients examined by the fifth day of the illness. These findings suggest that CNS complications including encephalitis/encephalopathy occur at the pre-eruptive stage of exanthem subitum, that human herpesvirus 6 invades the CNS in some patients, and that the outcome is not always benign.

No abstract

The isolation of human herpesvirus 7 (HHV-7) from saliva and blood, and the prevalence of antibodies to the virus in healthy individuals were investigated in Japan. By cocultivating samples with phytohemagglutinin-P-stimulated cord blood mononuclear cells, HHV-7 was isolated from the saliva of 1 of 20 children and from 4 of 38 adults but not from their blood. The isolates were confirmed as closely related to RK strain of HHV-7, but not to U1102 (human herpesvirus 6, HHV-6 type A) or Z29 (HHV-6 type B) strains by restriction cleavage patterns of the DNA. The virus antibody of 330 healthy children and adults was measured with an indirect immunofluorescence assay, using one of our isolates (FG7-6). The positivity rate of antibody was 40% in the first 2 months of life, declined during the first 6 months, then gradually increased and was 45% at 1-4 years of age. It reached the highest level (60%) at 11-13 years of age and was maintained until the end of the third decade, then decreased thereafter. Additionally, no simultaneous rise in the antibody titers was observed in 7 virologically confirmed exanthem subitum patients.