XXXX sequence according to the distance between the first sacral vertebra and the ilia.

@entity1029 @entity4218 @entity4219
The development of the iliac bones and lower limbs are parallel processes depending on the normal ontogeny of the caudal blastema [O'Rahilly and M  ller, 1989; Opitz, 1993; Opitz et al., 2000]. We hypothesized that the pathogenetic mechanisms leading to fused lower limbs would in parallel displace the ilia caudally and medially and that the degree of this displacement might correlate with the severity of the iliac and lower @entity4218 . Thus the purpose of the study was to test this hypothesis in a sample of 12 sirenomelic fetuses. The fetuses GA 16-39 weeks, spontaneously or therapeutically aborted, were radiographed in the frontal projection as part of a requested autopsy. From each radiograph, a line was drawn connecting the most cranial part or the two ilia. After that the distance was measured vertically between this line and the most cranial part of the first sacral vertebral body ( @entity1029 ( @entity1029 )). A second distance was measured horizontally between the most lateral part of the two iliae (bi-iliac distance (BD)). As a result, @entity1029 correlates with the iliac/femur phenotype. Separate ilia and femora occur only in cases with normal @entity1029 . Fused ilia or femora or both are seen only in fetuses with mildly increased @entity1029 , whereas a single iliac bone and femur occur only in cases with greatly increased @entity1029 . The increase of the @entity1029 does not correlate with the severity of more distal limb involvement. There was a correlation between the @entity1029 and the BD values; the higher the @entity1029 , the shorter the BD. Based on these findings, we propose an extended classification of @entity4219 to be tested by other researchers.
