. Author manuscript; available in PMC: 2020 Oct 1.

Published in final edited form as: Hum Genet. 2019 Aug 30;138(10):1183–1200. doi: 10.1007/s00439-019-02057-x

Table 1.

Summary of clinical and neurological findings for six probands with GPT2 mutations

Patient	1.1	1.2	2.1	3.1	3.2	3.3
Consanguinity (parental relatedness)	No	No	No	Yes	Yes	Yes
Gender	Female	Male	Male	Male	Female	Female
Age at examination	15 y	13 y	17 y	17 y	14 y	10 y
Intellectual disability	Moderate	Moderate	Moderate	Severe to profound	Severe to profound	Severe to profound
Weight at birth	54^th percentile	59^th percentile	2^nd percentile	NA	NA	NA
Head circumference at examination	1^st percentile	1^st percentile	<1^st percentile	<1^st percentile	<1^st percentile	<1^st percentile
Height at examination	NA; <5^th percentile throughout childhood	NA; <1^st percentile based on most recent clinical note	21^st percentile	1^st percentile	<1^st percentile	<1^st percentile
Weight at examination	NA; <5^th percentile throughout childhood	NA; <1^st percentile based on most recent clinical note	10^th percentile	8^th percentile	1^st percentile	2^nd percentile
Motor development	Delayed motor signs by 17 mo; apraxia	Delayed motor signs by 9–12 mo; head holding at 2–3 mo; standing at 14 mo	Normal gross motor development	Delayed motor development	Delayed motor development	Delayed motor development
Age of being able to walk	4 y	2 y	13–14 mo	3 y	4 y	6 y
Subsequent deterioration in walking	No	No	No	Yes, after fall at 4 y	No	No
Speech	Dysarthria; globally impaired	Dysarthria; speech apraxia; globally delayed	Delayed	Non-verbal; communicates with gestures	Monotone speech; some dysarthria	Monotone speech; some dysarthria
Oral-motor function	Drooling; vomiting	Drooling; vomiting	Normal	Severe impairment in oral-motor skills; drooling	Severe impairment in oral-motor skills; drooling	Severe impairment in oral-motor skills; drooling
Motor examination	Spasticity; increased tone in legs in terms of rotation; hyperreflexia; bilateral coordination impaired; wide-based gait; mild scissoring	Spasticity; increased tone in legs in terms of rotation; hyperreflexia in all joints, with 4–5 beats of clonus bilaterally in ankles	Strength and tone normal; abnormal gait	Hyperreflexia at all joints; severely impaired coordination	Strength reduced (power 3/5); tone normal; no spasticity of upper or lower limbs; hyperreflexia at all joints; poor motor coordination	Strength reduced (power 4/5); tone normal; no spasticity of upper or lower limb; hyperreflexia at all joints; severely impaired coordination
Data supporting seizures/epilepsy	1^st seizure at 9 y; EEG in 2012 showed bursts of generalized 3-Hz spike and wave activity	1^st seizure around 9 y; medically refractory epilepsy; currently prescribed lamotrigine and cannabidiol oil	No seizures observed	Equivocal falling behavior, but seizure workup unavailable	No seizures observed	Equivocal falling behavior, but seizure workup unavailable
Imaging	CT/MRI-MR spectroscopy in 2008 normal	MRI showed bilateral prominent perivascular spaces at centrum semiovale	CT of head normal	Low resolution MRI normal	Low resolution MRI normal	Low resolution MRI normal
GPT2 mutation^a	Compound heterozygous c.812A>C (p.N271T)/c.1432_1433delGT (p.V478Rfs*73)	Compound heterozygous c.812A>C (p.N271T)/c.1432_1433delGT (p.V478Rfs*73)	Homozygous c.775T>C (p.C259R)	Homozygous c.1210C>T (p.R404*)	Homozygous c.1210C>T (p.R404*)	Homozygous c.1210C>T (p.R404*)

Positions of mutations are according to transcript NM_133443.3.

y years, mo months, NA not available