Table 2.
Clinical Features Shared among Three or More Individuals with a GNB1 Germline De Novo Mutation
| Description of HPO Term | HPO Term | No. of Individuals (of 13) | c.227A>G (p.Asp76Gly) | c.228T>G (p.Asp76Glu) | c.229G>A (p.Gly77Ser) | c.233A>G (p.Lys78Arg) | c.239T>A (p.Ile80Asn) (of two) | c.239T>C (p.Ile80Thr) (of three) | c.284T>C (p.Leu95Pro) | c.301A>G (p.Met101Val) (of two) | c.976G>A (p.Ala326Thr) |
|---|---|---|---|---|---|---|---|---|---|---|---|
| Global developmental delay | HP:0001263 | 13 | + | + | + | + | ++ | +++ | + | ++ | + |
| Hypotonia | HP:0001252 | 11 | + | − | + | + | ++ | +++ | + | + | + |
| Seizures | HP:0001250 | 10 | − | + | − | + | ++ | ++ | + | ++ | + |
| Growth delay | HP:0001510 | 6 | − | − | − | + | ++ | ++ | + | − | − |
| Multifocal epileptiform discharges | HP:0010841 | 5 | − | − | − | − | + | ++ | + | + | − |
| Expressive language delay | HP:0002474 | 4 | − | − | − | − | − | ++ | + | + | − |
| Failure to thrive | HP:0001508 | 4 | − | + | − | − | + | + | + | − | − |
| Feeding difficulties | HP:0011968 | 4 | − | − | − | + | ++ | − | + | − | − |
| Intellectual disability | HP:0001249 | 4 | + | − | − | − | − | − | + | + | + |
| Limb hypertonia | HP:0002509 | 4 | − | + | − | − | + | + | + | − | − |
| Strabismus | HP:0000486 | 4 | − | + | − | + | − | + | + | − | − |
| Cortical visual impairment | HP:0100704 | 3 | − | − | − | − | ++ | − | + | − | − |
| Developmental regression | HP:0002376 | 3 | − | − | − | − | − | + | − | ++ | − |
| Early-onset hypotonia | HP:0008947 | 3 | + | − | − | + | + | − | − | − | − |
| EEG with generalized epileptiform discharges | HP:0011198 | 3 | − | − | − | + | − | + | − | + | − |
| Focal seizures with impairment of awareness | HP:0002384 | 3 | − | + | − | − | + | − | − | + | − |
| Generalized tonic-clonic seizures | HP:0002069 | 3 | − | − | − | − | − | − | − | ++ | + |
| Inability to walk | HP:0002540 | 3 | − | − | − | − | − | ++ | + | − | − |
| Nystagmus | HP:0000639 | 3 | − | − | − | − | − | ++ | + | − | − |
Abbreviations are as follows: HPO, Human Phenotype Ontology; and EEG, electroencephalogram.