Table 1 Phenotype of patients with the UBTF c.628G>A variant

Gender

1M/6F

2M/2F

1M

1M

5M/8F

Age at publication, yo (median, interval)

17 [8 - 23]

12 [6 – 33]

13

12

13 [6 – 33]

Age at regression, yo, (median, [interval])

3.5 [2.5 – 7]

2.7 [2 – 3]

1.3 – 2

5.8

3 [2 – 7]

DD prior to regression

3

0

Mild speech delay

Yes

5 (33%)

Microcephaly

6 acquired (1 borderline)

1 acquired (borderline)

NA

No

7/12 (58%)

Ataxia

3

4

1 (early on)

1 (early on)

9 (67%)

Extrapyramidal signs

6 (3 dystonia, 2 rigidity,1 chorea)

3 (3 dystonia, 1 chorea)

1(dystonic attacks)

1 (dystonia, chorea)

11 (85%)

Pyramidal signs

6

4

Yes

Brisk DTR

12 (92%)

Behavioural disorders

NA

4 (hyperactivity, impulsivity, ‘autistic behaviour’)

Apathy, social interaction difficulties

Apathy, agitation, friendly

6/6 (100%)

Dysarthria

NA

4

NA

Yes

5/5 (100%)

Swallowing difficulties

NA

3

Yes (11yo)

Yes (11 yo)

5/6 (83%)

Seizures/Epilepsy

3 (onset 5, 14 and 15yo)

0

Yes (multiple types) 6 yo

Yes (behavioural arrest) 11 yo

5 (38%)

Outcome

7 non verbal with profound ID, 6 non ambulatory

4 language regression, 1 non ambulatory, 1 few steps, 4 severe ID

Non verbal, severe ID, non ambulatory

Non verbal, severe ID, non ambulatory

13 non verbal or severe language impairment and severe ID (100%), 9 non ambulatory (69%), 1 limited ambulation

EEG abnormalities

4 (no details)

Abnormal background rhythms

Diffuse β activity (5yo), sharp waves (6yo), continuous bilateral FT spikes, slow background.

Yes (see text)

7 abnormal (53%)

Brain MRI

7 cerebral atrophy and T2 white matter hs, 5 cerebellar atrophy

4 cerebral atrophy, cerebellar atrophy and white matter hs

Cerebral atrophy, white matter hs

Cerebral atrophy, mild cerebellar atrophy, white matter hs

13 cerebral atrophy and white matter hs (100%), 10 cerebellar atrophy (77%)