Male-to-male transmission in Laurin-Sandrow syndrome and exclusion of RARB and RARG.

We report on a father and a son with nasal and limb defects characteristic of Laurin-Sandrow syndrome (LSS) excluding for the first time X-linked inheritance in this rare condition. Based on a search for genes expressed late during nose formation and early in limb formation we identified retinoic acid receptor B (RARB) and retinoic acid receptor G (RARG) as possible candidate genes and sequenced bidirectionally including all exons and intron-exon bounders. We identified a single nucleotide substitution in intron 2 of RARB, which is conserved in human, chimp, dog, mouse, rat, and chicken. However, it was located 83 bp from exon 2, suggesting it is a rare polymorphism which does not account for the phenotype. No other mutations were found. This suggests that another yet unknown gene is responsible for the condition.