syndromic disease spondylolisthesis Jaffer-Beighton syndrome https://rarediseases.info.nih.gov/diseases/3040/jaffer-beighton-syndrome Jaffer Beighton syndrome MEDGEN:444079 UMLS:C2931533 MESH:C537561 arachnodactyly, joint laxity, and spondylolisthesis MONDO:0023510