NFIX and Malan overgrowth syndrome: Malan Syndrome (MS) (MIM #614753) is an autosomal dominant ultra-rare overgrowth condition caused by haploinsufficiency of the Nuclear Factor I X gene (NFIX; MIM #164005) due to heterozygous loss-of-function (LoF) pathogenic variants almost exclusively clustering within exon 2 of NFIX with few exceptions or to chromosomal microdeletions involving the 19p13.2 region.