Background. METTL5 gene is one of the members of methyltransferase superfamily and biallelic variants cause intellectual disability syndrome (ID) with microcephaly. This article reports three new cases with METTL5 related ID syndrome in a consanguineous family.

Case. Afghanistan descent family was affected by a novel homozygous c.362A > G (p.Asp121Gly) METTL5 gene variant. This variant is predicted to be `pathogenic` by multiple in-silico tools. Patients had dysmorphic and neurodevelopmental features including intellectual disability, microcephaly, poor/absent speech, delayed walking, aggressive behavior, large/posteriorly rotated ears, broad nasal base and short stature, which seem to be the cardinal findings of the designated syndrome.

Conclusions. While the data reported in these individuals indicate characteristic clinical features of METTL5 related ID syndrome, further investigations and study of additional cases are needed to improve the understanding of disease pathogenesis, and management.

Keywords: METTL5, WES, intellectual disability, whole exome sequencing