Exclusion of linkage to the HLA region in ninety multiplex sibships with autism.

Scientists looked at ninety families. Each family had more than one child with autism.

They checked if brothers and sisters shared the same HLA genes on chromosome 6. Shared genes would mean the spot is linked to autism.

The kids did not share HLA alleles more than chance. The region showed no link to autism.

This tells us the HLA area is probably not a big autism gene hot spot.

Allen-Brady et al. (2010) later found a hint of linkage on the X chromosome in high-risk families. They used the same kind of multiplex families but looked elsewhere after this null result.

Castermans et al. (2004) wrote a review saying linkage scans often come up empty. They urged the field to hunt chromosome breaks instead of doing more big scans.

Gaily et al. (1998) had earlier looked for big chromosome changes in kids with PDDs and found very few. Together these papers show the move from eyeballing chromosomes under the microscope to DNA-level linkage hunts.

When you talk genes with families, you can say the HLA region is unlikely to cause autism. Focus risk counseling on newer findings or on broad heritability, not on this old candidate spot.