Over 2,400 years ago, Hippocrates noticed that eye misalignment, or strabismus, tended to cluster in families. This observation represents an early recognition of what we now recognize as genetic causes. However, genetic causes of isolated strabismus, which occur in the absence of other symptoms, remain elusive.

In a large family, we identify a piece of chromosome 14 that is linked to isolated strabismus. Larger disruptions in the same portion of chromosome 14 cause FOXG1 syndrome, and 84% of these individuals have strabismus. Strabismic individuals from this study share a four-letters deletion in the DNA sequence. A previous study of mouse brain development suggests this specific location in the DNA may function by changing when or where the FOXG1 gene is active. (By Cynthia Ye, https://jmg.bmj.com/content/early/2020/11/29/jmedgenet-2020-107226 )