Table 2.
Neurological, developmental, and other clinical features of families with biallelic GRM7 variants.
| Individual | Age at last exam | OFC‐last exam cm (z‐score) | Microcephaly | Axial hypo‐tonia | Peripheral hyper‐tonia | Hyper‐reflexia | DD/ID | Seizures (onset) | DRE (Current AEDs) | Seizure types | SE | Other clinical features |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Family 1, II‐1 (BAB6709)* | 13 yrs. | 50 cm (−2.9SD) | + | + | + | + | + | + (4 mo.) | − (LEV and RFM‐effective) | Myoclonic | − | FTT, RI, dysphagia, anemia (B12 & iron deficiency), hypothyroidism, bilateral hyperopia, and occasional self‐mutilation |
| Family 1, II‐2 (BAB6708)* | 10 yrs. | N/A | N/A | + | + | + | + | + (8 mo.) | − (none) | GTCs (seizure free off AEDs for 5 yrs with subsequent recurrence) | − | N/A |
| Family 2, II‐1 (BAB8506)* | 15 yrs. | 50.5 cm (−3.31SD) | + | + | + | − | + | + (1 mo.) | + (LEV and VNS) | Myoclonic & GTCs | + (one admission) | FTT, SS, dysphagia, cortical visual impairment, GH deficiency, hypotonic facies, vitamin D deficiency, low bone density, and stool incontinence |
| Family 2, II‐2 (BAB8506's brother)* | 10 yrs. | 48.6 cm (−3.29SD) | + | + | + | N/A | + | + (DOL1) | + (LEV, ZNS, and VNS) | Myoclonic & GTCs | − | FTT, SS, dysphagia, cortical visual impairment, hypotonic facies, and micropenis |
| Family 3, II‐2 (MR005‐1)* | N/A | N/A (<−2 SD) | + | N/A | N/A | N/A | + | + | N/A | N/A | N/A | FTT, RI, SS, and lipodystrophy |
| Family 3, II‐6 (MR005‐2)* | 5 yrs. 6 mo. | N/A (<−2 SD) | + | N/A | + | N/A | + | + (3 w) | N/A | N/A | N/A | FTT, RI, SS, “hormonal deficiency,” and lipodystrophy |
| Family 4, II‐1 | 13 mo. | N/A | N/A | + | N/A | N/A | + | + (3 mo.) | + (VPA and PB) | N/A | + (ICU admission at 8 mo) | Dysphagia (nasogastric tube feeding), hepatomegaly, and an episode of hypoglycemia |
| Family 4, II‐4 | 1 mo. | N/A | N/A | N/A | N/A | N/A | + | + (1 w) | − | N/A | N/A | N/A |
| Family 4, II‐6 (BAB13620) | 3 yrs. 3 mo. | 42.5 (−3.8 SD) | + | + | − | − | + | + (5 mo.) | + (VPA, LEV, and CLB) | GTCs & focal | − | RI, SS, cortical visual impairment, panhypopituitarism on hydrocortisone and thyroid hormone replacement, mild peripheral pulmonary stenosis, conductive hearing loss, CSA, ASD, concern for long QT syndrome, and HIE following aspiration at 3y 3m |
| Family 5, II‐1 (BAB10502) | 7 mo. | 40 cm (−3.2 SD) | + | + | + | + | + | + (2 mo.) | + (PB, CLB, LEV) | Myoclonic & GTCs | + (2 admissions) | RI, OSA, anemia, and unilateral hearing loss |
| Family 6, II‐1 (BAB10517) | 20 mo. | 44.5 cm (−2.7 SD) | + | + | + | + | + | + (2d) | + (TPM, LMG, VPA, and CLB) | Multifocal | + (multiple ICU admissions) | FTT, RI, and anemia |
| Total | 8/8 | 8/8 | 7/8 | 4/6 | 11/11 | 11/11 | 6/9 | 4/8 |
ADHD, attention deficit hyperactivity disorder; AED, antiepileptic drug; ASD, atrial septal defect; CLB, clobazam; CSA, central sleep apnea; DD, developmental delay; DOL, date of life; DRE, drug‐resistant epilepsy; FTT, failure to thrive; GH, growth hormone; GTC, generalized tonic‐clonic; HIE, hypoxic ischemic injury; ICU, intensive care unit; ID, intellectual disability; mo., months; LEV, levetiracetam; LMG, lamotrigine; N/A, not available; OSA, obstructive sleep apnea; PB, phenobarbital; RI, recurrent infections; SE, status epilepticus; SS, short stature; TPM, topiramate; VNS, vagal nerve stimulator; VPA, valproic acid, w, weeks; yrs., years; ZNS, zonisamide.
Previously published with limited clinical data.