Table 1.

Clinical features of individuals with chromosomal duplication encompassing FGF12

	Individual 1	Individual 2	Individual 3
Genome coordinates FGF12 duplication (chr3; hg19)	191 860 089‐192 451 114	191 876 968‐192 454 685	191 876 968‐192 454 685
Age at last examination	10 y	3 y	30 y
Age at seizure onset	12 mo	13 mo	1 mo
Seizure types	Tonic‐clonic, atonic, tonic, myoclonic, autonomic	Generalized tonic‐clonic and history of febrile seizures Myoclonic jerks	Generalized tonic‐clonic
EEG	Sowed background and multifocal seizures	Normal	Normal
AED treatment	Sodium valproate, clobazam, lamotrigine, and topiramate	Valproate	Valproate, carbamazepine, lamotrigine, levetiracetam
Other treatments	Vagal nerve stimulator Ketogenic diet	—	—
DD/ID	Severe DD/ID No speech Wheelchair dependent	Developmental delay	Developmental delay
Other neurological symptoms	Ataxia	Unsteady	Unsteady and migraine
Brain MRI	Bilateral delayed myelination in the parieto‐occipital region	Mild prominence of the subarachnoid space in the frontal regions bilaterally otherwise normal	Normal
Feeding difficulties	+, progressive, requiring PEG	No	No
Recurrent infection	+, upper airway	No	Perianal abscess Dental infections