Most individuals with Williams syndrome (WS) have a 1.6 Mb deletion in chromosome 7q11.23 that encompasses the elastin (ELN) gene, while most families with autosomal dominant supravalvar aortic stenosis (SVAS) have point mutations in ELN. The overlap of the clinical phenotypes of the two conditions (cardiovascular disease and connective tissue abnormalities such as hernias) is due to the effect of haploinsufficiency of ELN. SVAS families often have affected individuals with some WS facial features, most commonly in infancy, suggesting that ELN plays a role in WS facial gestalt as well. To find other genes contributing to the WS phenotype, we studied five families with SVAS who have small deletions in the WS region. None of the families had mental retardation, but affected family members had the Williams Syndrome Cognitive Profile (WSCP). All families shared a deletion of LIMK1, which encodes a protein strongly expressed in the brain, supporting the hypothesis that LIMK1 hemizygosity contributes to impairment in visuospatial constructive cognition. While the deletions from the families nearly spanned the WS region, none had a deletion of FKBP6 or GTF2I, suggesting that the mental retardation seen in WS is associated with deletion of either the centromeric and/or telomeric portions of the region. Comparison of these five families with reports of other individuals with partial deletions of the WS region most strongly implicates GTF2I in the mental retardation of WS.

The chromosome banding patterns of eight species of birds of the order Galliformes have been compared to determine their degree of chromosomal homology. The species studied were domestic chicken (Gallus gallus), Japanese quail (Coturnix coturnix), guineafowl (Numida meleagris), peafowl (Pavo cristatus), Ring-necked pheasant (Phasianus colchicus), turkey (Meleagris gallopavo), Sagegrouse (Centrocercus urophasianus), and Bob-white quail (Colinus virginianus). These species were selected as key genera in a preliminary study of evolutionary relationships in the order Galliformes.The chromosome banding patterns defined two major groups, with Gallus most nearly approaching the ancestral karyotype. Gallus, Numida, Coturnix, and Pavo retain the ancestral submetacentric chromosome 2, which also occurs in the cracid, Crax mitu (DeBoer and Belterman, 1981), and certain other bird orders. Coturnix differs from Gallus by four inversions. Numida differs from Gallus by a centric fusion of two microchromosomes which formed a unique new macrochromosome. Pavo differs from Gallus by two centric fusions which result in two unique macrochromosomes. The second major group, Phasianus, Meleagris, Colinus, and Centrocercus all lack the submetacentric 2 and have two separate chromosomes in its place as a result of a centric fission event. All of these species also possess the unmodified 4 seen in C. mitu, in place of the modified 4 seen in the Gallus group. Meleagris is similar to Phasianus; it differs mainly by an inversion on the Z chromosome. Colinus differs from Phasianus by an inversion on 1. Centrocercus differs from Phasianus by a centric fusion which produced a unique chromosome. Gallus, Pavo, Numida, and Coturnix are related but distinct lines which are clearly separate from Phasianus. Meleagris, Colinus, and Centrocercus represent closely related lines that developed in the new world from an early North American phasianid. Chromosome banding patterns indicate that the ancestral stock was karyotypically similar to Phasianus. Comparison of the data from this study and that of DeBoer and Belterman (1981) for C. mitu indicates a close relationship of the cracids to other galliform birds, in contrast to the opinion of Prager and Wilson (1979) based on studies of lysozymes and other proteins. The chromosome data supports the conclusions from several other lines of investigation that challenge the taxonomic treatment of the Galliformes which regards the turkey, guinea fowl, and grouse as belonging to separate families, yet unites divergent lines such as Old World quail, New World quail, peafowl, and true pheasants into a single family, Phasianidae. Treatment of each of the major lines indicated in this study at the subfamily level seems more consistent with the available data.

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Summary CD34+ progenitor cells can harbour latent human cytomegalovirus (HCMV); however, the mechanisms of HCMV latency remain unclear. We have investigated the effects of the haematopoietic lineage restriction on the establishment and spread of the latent HCMV to progeny cells. In vitro‐infected and latently‐infected haematopoietic progenitor cells derived from HCMV seropositive donors were studied. The presence of HCMV DNA in bone marrow progenitor (BMP) cells was determined by single colony polymerase chain reaction and fluorescent in situ hybridization (FISH). The presence of CMV DNA was found to be restricted to myeloid progenitors and the percentage of HCMV‐infected cells was lower in naturally‐infected cells than in in vitro‐infected cells. Erythroid differentiation resulted in an abortive infection with persistence of the viral nucleic acids in red cell precursors. In BMP cells from HCMV seronegative donors, HCMV DNA was localized in the nucleus. Bone marrow progenitors in the presence of granulocyte‐macrophage colony stimulating factor (GMCSF) maintained HCMV DNA for extended periods of time. No viral production could be detected throughout the culture but the comparison of the numbers of latently‐infected cells prior to and after the culture suggests that proliferation of haematopoietic progenitor cells may lead to the expansion of latently‐infected cells.

Supravalvular aortic stenosis (SVAS) is an autosomal dominant disorder characterized by abnormalities of development of the great vessels. SVAS is also commonly part of Williams syndrome. Linkage to the elastin gene on chromosome 7q11 has recently been reported in two kindreds with SVAS. Previous reports of patients with 7q11 deletions have noted great vessel abnormalities in some. We report on a family in which SVAS is cosegregating with a balanced reciprocal translocation, t(6:7) (p21.1;q11.23), providing further evidence that SVAS is the result of a mutation of elastin at 7q11.23 region. The propositus of the translocation family has some minor anomalies which occur in Williams syndrome, suggesting that elastin abnormalities may cause some of the abnormalities found in Williams syndrome.