Table 1 Clinical features of FMR1-related disorders.

From: Laboratory testing for fragile X, 2021 revision: a technical standard of the American College of Medical Genetics and Genomics (ACMG)

Disorder

OMIM

Main clinical features

Associated FMR1 variant

Fragile X syndrome (FXS)

300624

Cognitive deficit, seizures, macro-orchidism, large ears, autism spectrum disorder

Full-mutation allele (99%), FMR1 sequence variants, FMR1 gene deletion

Fragile X primary ovarian insufficiency (FXPOI)

311360

Premature ovarian insufficiency, amenorrhea

Premutation

Fragile X tremor ataxia syndrome (FXTAS)

300623

Tremor, cerebellar gait ataxia, MRI white matter lesions

Premutation

Fragile X–associated neuropsychiatric disorders (FXAND)

None

Anxiety, depression, ADHD, addictive behavior

Premutation

  1. The main clinical features for each disorder can be variable and are part of a larger clinical spectrum.
  2. ADHD attention-deficit/hyperactivity disorder, MRI magnetic resonance imaging.
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