MedGen

Developmental and epileptic encephalopathy-98 (DEE98) is characterized by onset of seizures in the first decade (range infancy to late childhood) associated with variable global developmental delay. Other features may include hypotonia, spasticity, and quadriparesis. Brain imaging may be normal or show nonspecific and variable abnormalities, including polymicrogyria. The severity is variable; some patients may die of refractory status epilepticus (summary by Vetro et al., 2021). For a general phenotypic description and a discussion of genetic heterogeneity of DEE, see 308350. [from OMIM]

Mitochondrial complex V deficiency nuclear type 7 (MC5DN7) is an autosomal recessive disorder characterized by hypotonia and global developmental delay apparent soon after birth. More variable features include poor growth, seizures, dystonia, hypertrophic cardiomyopathy, and brain imaging abnormalities. Some affected individuals die in infancy or childhood (Zech et al., 2022, Ganapathi et al., 2022). For a discussion of genetic heterogeneity of mitochondrial complex V deficiency, nuclear types, see MC5DN1 (604273). [from OMIM]