Beschreibung:
<jats:p>Intellectual development disorder, autosomal dominant 43 (MRD43) is an autosomal dominant disorder caused by heterozygous mutations in the <jats:italic>HIVEP2</jats:italic> gene. In this report, we describe a case of a 4-year-old boy with global development delay, hypotonia, and dysmorphic features, in whom the finding of a heterozygous nonsense pathogenic variant in exon 5 of <jats:italic>HIVEP2</jats:italic> [c.2827C&gt;T p. (Arg943*)] through WES established a MRD43 diagnosis. Our patient’s phenotype overlaps with other MRD43 descriptions in the literature. Unlike previously reported cases, where the condition was almost invariably <jats:italic>de novo</jats:italic>, the healthy mother in this case presented mosaicism for the pathogenic variant. Thus, the recurrence risk increased significantly from 1% to up to 50%. The description of a variant inherited for MDR43 is singular in the literature and this description highlights the importance of parental studies for accurate genetic counseling, particularly for family planning.</jats:p>