Background Paroxysmal tonic upgaze (PTU), defined as an involuntary upward movement of the eyes, has been considered as a benign phenomenon but may also be associated with ataxia and developmental delay. To date, CACNA1G mutations have been reported in autosomal dominant spinocerebellar ataxia designated SCA42 and in early encephalopathies with cerebellar atrophy but never in periodic childhood manifestations of PTU type. Methods and Results We report the case of a two-month-old infant with a de novo pathogenic variation of CACNA1G who presented with PTU associated with congenital ataxia and other periodic neurological manifestations. Conclusions Although the link between CACNA1G mutations and periodic neurological manifestations remains unclear, we provide detailed video documentations of PTU, paroxysmal torticollis, and ataxia in a patient with a CACNA1G mutation. This case allows a better understanding of the underlying mechanisms of PTU and suggests potential new avenues for clinical treatments.