Mesoaxial polydactyly is a major feature in Bardet-Biedl syndrome patients with LZTFL1 (BBS17) mutations

Clin Genet. 2014 May;85(5):476-81. doi: 10.1111/cge.12198. Epub 2013 Jun 12.


Ciliopathies are heterogeneous disorders sharing different clinical signs due to a defect at the level of the primary cilia/centrosome complex. Postaxial polydactyly is frequently reported in ciliopathies, especially in Bardet-Biedl syndrome (BBS). Clinical features and genetic results observed in a pair of dizygotic twins with BBS are reported. The following manifestations were present: retinitis pigmentosa, bilateral insertional polydactyly, cognitive impairment and renal dysfunction. X-rays of the hands confirmed the presence of a 4th mesoaxial extra-digit with Y-shaped metacarpal bones. The sequencing of LZTFL1 identified a missense mutation (NM_020347.2: p.Leu87Pro; c.260T>C) and a nonsense mutation (p.Glu260*; c.778G>T), establishing a compound heterozygous status for the twins. A major decrease of LZTFL1 transcript and protein was observed in the patient's fibroblasts. This is the second report of LZTFL1 mutations in BBS patients confirming LZTFL1 as a BBS gene. Interestingly, the only two families reported in literature thus far with LZTFL1 mutations have in common mesoaxial polydactyly, a very uncommon feature for BBS. This special subtype of polydactyly in BBS patients is easily identified on clinical examination and prompts for priority sequencing of LZTFL1 (BBS17).

Keywords: Bardet-Biedl syndrome; LZTFL1 gene; ciliopathy; mesoaxial polydactyly.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Bardet-Biedl Syndrome / genetics*
  • Bardet-Biedl Syndrome / physiopathology
  • DNA Mutational Analysis
  • Female
  • Fingers / abnormalities*
  • Fingers / physiopathology
  • Heterozygote
  • Humans
  • Mutation / genetics*
  • Pedigree
  • Polydactyly / genetics*
  • Polydactyly / physiopathology
  • Toes / abnormalities*
  • Toes / physiopathology
  • Transcription Factors / genetics*
  • Twins


  • LZTFL1 protein, human
  • Transcription Factors

Supplementary concepts

  • Polydactyly, Postaxial