Heterozygous mutations in the NFIX gene can lead to two rare allelic disorders, Malan syndrome (MAL; MIM #614753) and Marshall‐Smith syndrome (MSS; MIM #602535).(1, 9) MAL is an overgrowth disorder, characterized by a slender habitus, long hands and advanced bone age, moderate to severe intellectual disability, unusual facial phenotype consisting of a long, triangular face with a prominent forehead, everted lower lip and prominent chin, and behavioral problems, which are usually dominated by anxieties and, less frequently, by aggression(9, 10, 11, 12) (Table S1). Here, NFIX is linked to Malan overgrowth syndrome.