Table 1.
Demographic, developmental, and clinical manifestations of individuals with SSADHD
| Characteristic | SSADHD Study Group | Symptom Age of Onset |
|---|---|---|
| N = 62 (100%) | Years (median, IQR) | |
| Sex, M/F | 29 (47%) / 33 (53%) | - |
| Age, median (IQR) | 9.6 (5.4–14.5) | - |
| Symptom onset (caregiver-reported) | - | 0.5 (0.2–0.7) |
| Diagnosis | - | 3.5 (2.0-5.4) |
| Developmental milestones achieved | ||
| Head control | 61 (98%) | 0.5 (0.3–0.6) |
| Sitting unsupported | 60 (97%) | 0.9 (0.6-1.0) |
| Walking unsupported | 56 (90%) | 1.6 (1.3–2.5) |
| First word | 54 (87%) | 2.3 (1.7-4.0) |
| Neuropsychologic | ||
| FSIQ / DQ, mean ± SD (N = 32) | 53.3 ± 13.6 | - |
| Adaptive composite score, median (IQR) (N = 27) | 65.0 (56.5–70.0) | - |
| Autism spectrum disorder diagnosis (N = 30) | 17 (57%) | 4.0 (2.0–12.0) |
| REEL-3 receptive age equivalent scores (N = 21) | 28.0 (16.0-34.5) | - |
| REEL-3 expressive age equivalent scores (N = 21) | 23.0 (9.7–33.5) | - |
| MABS percentile rank (N = 20) | 13.0 (10.0-22.5) | - |
| Epilepsy | 30 (48%) | 9.0 (5.0–12.0) |
| Drug-resistant epilepsy | 11 (18%) | - |
| EEG- diffuse background slowing (N = 55) | 24 (44%) | - |
| EEG- epileptiform patterns (N = 55) | 15 (27%) | |
| Motor and movement | ||
| GMFCS 1–3/4–5 | 53 (85%) / 9 (15%) | - |
| Hypotonia | 40 (64%) | 0.25 (0.0-0.5) |
| Ataxia | 25 (40%) | 1.5 (1.0–2.0) |
| Dystonia/Dyskinesia | 14 (22%) | 1.1 (0.6–10.5) |
| MRI (N = 39) | ||
| No cortical abnormality | 28 (71%) | - |
| T2-weighted hyperintense signal- globus pallidi | 18 (46%) | - |
| T2-weighted hyperintense signal- dentate nucleus | 18 (46%) | - |
| Psychiatric and Behavioral | ||
| CBCL/ABCL T-scores, mean ± SD (N = 27) | 59.68 ± 8.13 | - |
| OCD behaviors | 22 (35%) | 4.0 (2.0–9.0) |
| ADHD diagnosis | 28 (45%) | 5.0 (4.0-5.1) |
| Anxiety | 25 (40%) | 6.0 (3.0–13.0) |
| Psychosis | 3 (5%) | 5.0 (4.5–5.5) |
| Sleep disturbances | ||
| Reported sleep disturbances | 38 (61%) | 1.0 (0.1–1.6) |
| CSHQ-defined sleep disturbances (N = 32) | 25 (78%) | - |
| Total CSHQ score, mean ± SD (N = 32) | 47.8 ± 8.1 | - |
ABCL- Adult Behavior Checklist; ADHD- Attention-deficit/hyperactivity disorder; CBCL- Child Behavior Checklist; CSHQ- Children’s Sleep Habits Questionnaire; DQ- Developmental quotient; EEG- Electroencephalography; FSIQ- Full scale intelligence quotient; GMFCS- Gross Motor Function Classification System; IQR- Interquartile range; MABS- Movement Assessment Battery for Children; MRI- Magnetic resonance imaging; OCD- Obsessive-compulsive disorder; REELS- Receptive expressive emergent language scales; SD- Standard deviation; SSADHD- Succinic semialdehyde dehydrogenase deficiency