Infantile-onset parkinsonism, dyskinesia, and developmental delay: do not forget polyglutamine defects!

We present the phenotype of an infant with the largest ATN1 CAG expansion reported to date (98 repeats). He presented at 4 months with developmental delay, poor eye contact, acquired microcephaly, failure to thrive. He progressively developed dystonia-parkinsonism with paroxysmal oromandibular and limbs dyskinesia and fatal outcome at 17 months.