These authors identify two loss-of-function variants in FLG as being associated with icthyosis vulgaris and atopic dermatitis: S2554* and a 4-bp deletion of a “CAGT” sequence that causes a frameshift starting at codon 715.
It is unclear exactly how many families were studied — the paper mentions 15 kindred, but Figure 2 and other mentions describes 7 families. There are also eight sporadic cases, all of which had these mutations (4 hom for R501X, 4 compound het for both). The authors also report very high combined LOD scores for the families: “the maximum combined two-point lod score for families 1-7 (Fig. 2) was 8.11 at theta = 0”.
The authors analyze these variants as having incomplete penetrance, with heterozygotes having a very mild phenotype with palmar hyperlinearity, keratosis pilaris and, in some cases fine scale, while homozygotes had marked presentation of ichtyosis vulgaris with prominent scaling.
The 4bp-deletion in this paper is different from FLG-S761shift (FLG-S761Shift is farther downstream, caused by a deletion of “ACTG”), but it is very similar — S761Shift would be predicted to have a similar effect to the two variants described in this paper.