FAM160B1 deficit associated with microcephaly, severe intellectual disability, ataxia, behavioral abnormalities and speech problems

Intellectual disability (ID) varies in severity and is often associated with a variety of other clinical features. In consanguineous populations ID is usually inherited in an autosomal recessive fashion. Many genes are known for the condition, but many more are yet to be identified. By linkage analysis and exome sequencing we identified homozygous early truncating variant c.115G > T (p.Glu39*) in FAM160B1 in a 38-year-old woman with severe ID, microcephaly, behavioral abnormalities, speech problems, mild ataxia and mild facial dysmorphism. Recently homozygous missense c.248 T > C (p.Leu83Pro) was reported to underlie the ID syndrome in a 7-year-old boy and his two younger siblings. Some findings for those siblings overlap with those for our patient, but our patient does not have cutis laxa. Our findings confirm FAM160B1, with unknown function, as a syndromic ID gene and indicate that FAM160B1 is not essential for survival but is vital for proper functioning of the nervous system, delineate the FAM160B1-related ID, and describe the disease in a much older age.