The authors present the first case of infantile-onset spinocerebellar ataxia associated with a novel SPTBN2 mutation (transition C>T at nucleotide position 1438), the proband having a much more severe phenotype with global developmental delay, hypotonia, tremor, nystagmus, and facial myokymia.
Fifteen children presenting with infantile seizures, acquired microcephaly, and developmental delay were found to have novel heterozygous mutations in the GLUT1 (SLC2A1).
Our findings are compatible with the concept of truncating SPTBN2 mutations acting recessively, which is supported by disease expression in homozygous, but not heterozygous, knockout mice, ataxia in Beagle dogs with a homozygous frameshift mutation and, very recently, a homozygous SPTBN2 nonsense mutation underlying infantile ataxia and psychomotor delay in a human family.
The comparison of the clinical features between the 19 SLC2A1 mutated and the 226 non-mutated patients revealed that the onset of epilepsy within the first year of life (when associated with developmental delay or other neurological manifestations), the association of epilepsy with PD and acquired microcephaly are more common in mutated subjects.
Mutations in SLC2A1, encoding the glucose transporter type 1 (Glut1), cause a wide range of neurological disorders: (1) classical Glut1 deficiency syndrome (Glut1-DS) with an early onset epileptic encephalopathy including a severe epilepsy, psychomotor delay, ataxia and microcephaly, (2) paroxysmal exercise-induced dyskinesia (PED) and (3) various forms of idiopathic/genetic generalized epilepsies such as different forms of absence epilepsies.
We report five patients with non-progressive congenital ataxia and psychomotor delay, 4/5 harboring novel heterozygous missense variants in SPTBN2 and one patient with compound heterozygous SPTBN2 variants.
Here we report small, intragenic deletions of IGF1R, identified by chromosome microarray analysis in two unrelated families affected primarily with neuropsychiatric phenotypes including developmental delay, intellectual disability and aggressive/autoaggressive behaviors.
We report a six-year-old boy who presented with short stature, microcephaly, dysmorphic features, and developmental delay and who was identified with a terminal deletion of 15q26.2q26.3 containing the insulin-like growth factor receptor (IGF1R) gene in addition to a terminal duplication of the 4q35.1q35.2 region.
Notably, pathogenic substitutions of the homologous Gly77 residue including an identical variant (p.Gly77Arg, p.Gly77Val, p.Gly77Ser, p.Gly77Ala) of GNB1, a paralog of GNB2, was reported in individuals with global developmental delay and hypotonia.
Our results expand the genotype and phenotypes of SZT2-related DEEs, suggesting that SZT2 mutations play a role in developmental delay and epileptic encephalopathy, with high susceptibility to SE and relatively specific MRI findings.
COL4A1 mutations disrupt the integrity of vascular basement membranes, so predisposing to a broad spectrum of disorders including periventricular leucomalacia, haemorrhagic stroke, aneurysm formation, epilepsy and developmental delay.
To date, only 10 STAG2 pathogenic variants (four nonsense, four missense, and two frameshift) have been reported in patients with multiple congenital anomalies, ID, and DD.
Mutations in SZT2 have been reported in very few patients and features range from mild to moderate intellectual disability without seizures to severe intellectual disability with epileptic encephalopathies with severe developmental delay.
Using trio-based exome sequencing, we here identify de novo SOX4 heterozygous missense variants in four children who share developmental delay, intellectual disability, and mild facial and digital morphological abnormalities.