|Number of repeats||Counts (alleles)||Percentage|
Overview of repeats
Jacobsen syndrome (JBS) is a syndrome caused by partial deletion of chromosome 11 long arm. It has been shown that CGG repeat expansions in CBL gene causes expression of folate sensitive rare fragile site FRA11B which is close to many of the deletion breakpoints and expanded allele is likely the cause of the 11q deletion in two cases of JBS (Jones et al., 1995).
In healthy individuals the allele length has been shown to be between 8-80 repeats. Premutation alleles are considered to contain 85-100 repeats where repeats are highly unstable when transmitted to offspring. The full mutation is over 100 repeats (Jones et al., 1995) and could be responsible for the pathogenesis of the disease through methylated expanded repeats, which could delay DNA replication and thus, result in chromosome (Jones, 2000).