No abstract

We have determined the DNA sequence of the H-2Kb gene of the C57B1/10 mouse. Comparison of this sequence with that of the allelic H-2Kd shows surprisingly that the exons have accumulated more mutations than their introns. Moreover, many of these changes in the exons are clustered in short regions or hot spots. Additional comparison of these sequences with the H-2Ld and H-2Db sequences shows that, in several cases, the altered sequence generated at the hot spot is identical to the corresponding region of a non-allelic H-2 gene. The clustered changes are responsible for 60wo of the amino acid differences between the H-2Kb and H-2Kd genes and suggest that micro-gene conversion events occurring within the exons and involving only tens of nucleotides are an important mechanism for the generation of polymorphic differences between natural H-2 alleles.

No abstract

Several groups have reported weak evidence for linkage between schizophrenia and genetic markers located on chromosome 22q using the lod score method of analysis. However these findings involved different genetic markers and methods of analysis, and so were not directly comparable. To resolve this issue we have performed a combined analysis of genotypic data from the marker D22S278 in multiply affected schizophrenic families derived from 11 independent research groups worldwide. This marker was chosen because it showed maximum evidence for linkage in three independent datasets (Vallada et al., Am J Med Genet 60:139‐146, 1995; Polymeropoulos et al., Neuropsychiatr Genet 54:93‐99, 1994; Lasseter et al., Am J Med Genet, 60:172‐173, 1995). Using the affected sib‐pair method as implemented by the program ESPA, the combined dataset showed 252 alleles shared compared with 188 alleles not shared (chi‐square 9.31, 1df, P = 0.001) where parental genotype data was completely known. When sib‐pairs for whom parental data was assigned according to probability were included the number of alleles shared was 514.1 compared with 437.8 not shared (chi‐square 6.12, 1df, P = 0.006). Similar results were obtained when a likelihood ratio method for sib‐pair analysis was used. These results indicate that there may be a susceptibility locus for schizophrenia at 22q12. © 1996 Wiley‐Liss, Inc.

No abstract