Table 1.

Main clinical features of the patients harboring FGF14 mutation.

Family	Family A								Family B
Patient	IV‐10	III‐11	IV‐5	IV‐6	III‐8	IV‐9		III‐10	patient I‐2
Sex/age at last follow‐up (years)	M/5	M/37	M/6.5	M/6.5	F/45	F/3		F/NK	F/6.3
Acute episodes of ataxia	Yes	Yes	Yes	No	No	No		No	Yes
Age at onset (years)	2	8	2.8						2
Triggering factor	Febrile illness	Febrile illness, stress	Febrile illness						Febrile illness
Duration	2–7 days	7 days	2 days						7 days
Total number	8 No recurrence after age 4	2	1						Twice a year until last follo‐up
Symptoms	Vertigo, ataxia, nausea, vomiting, occacional confusion	Dizziness, ataxia	Ataxia						Severe ataxia
Other paroxysmal signs	No	No	2 access of breath holding spell at 3 months; between 2.8 and 5.5 years, daily access of gait unsteadiness with bizarre posture of the left limb lasting several hours	No	No	Brief episodes of lower limb hypertonia lasting some minutes between 7 and 9 months of age		No	No
Permanent symptoms	Yes	Yes	Yes	Yes	Yes	Yes		Yes	Yes
Tremor (age at onset)	No	UL postural tremor (from childhood)	No	UL postural tremor (from childhood)	UL postural tremor (from childhood)	UL postural tremor (from 2.5 years)	UL postural tremor (from childhood)		UL postural tremor (from infancy)
Nystagmus (age at onset)	Yes (from 24 months)	Yes (from infancy)	No	No	Yes	Yes (from infancy)		No	Yes (from infancy)
Permanent ataxia	No	No	No	No	No	No		No	No
Learning difficulties	No	No	Yes	Yes	Yes	No		NK	Yes
Psychomotor development	Normal	Normal	Language delay	Language delay	Normal	Normal		NK	Global delay
Paraclinical investigations (age)	Blood electrolytes, lactate, aminoacid, ammonemia, acylcarnitine dosage, urinary organic acid screening, cerebrospinal fluid analysis, auditory and vestibular assessment, brain MRI: normal (2 years)	None	Auditory and vestibular assessment, CGH‐array, FMR1 gene analysis, brain MRI normal (3.3 years)	None	None	None		None	EEG, brain MRI, ophthalmological assessment normal (1.2 years)

UL, upper limbs; M, male; F, female; NK, not known.