- Visual loss (HP:0000572): Loss of visual acuity (implying that vision was better at a certain time point in life). Otherwise the term reduced visual acuity should be used (or a subclass of that). Evidence: TAS. Frequency: Occasional (HP:0040283). (OMIM:611726)
- Progressive (HP:0003676): Applies to a disease manifestation that increases in scope or severity over the course of time, i.e., that worsens with age. Evidence: IEA. (OMIM:611726)
- Microcephaly (HP:0000252): Head circumference below 2 standard deviations below the mean for age and gender. Evidence: PCS. Frequency: 2/2. (PMID:22748208)
- Cerebral atrophy (HP:0002059): Atrophy (wasting, decrease in size of cells or tissue) affecting the cerebrum. Evidence: PCS. Frequency: 2/2. (PMID:22748208)
- Truncal ataxia (HP:0002078): Truncal ataxia is a sign of ataxia characterized by instability of the trunk. It usually occurs during sitting. Evidence: PCS. Frequency: 3/3. (PMID:17455289)
- Absent speech (HP:0001344): Complete lack of development of speech and language abilities. Evidence: PCS. Frequency: 2/2. (PMID:22748208)
- Generalized myoclonic seizure (HP:0002123): A generalized myoclonic seizure is a type of generalized motor seizure characterized by bilateral, sudden, brief (<100 ms) involuntary single or multiple contraction of muscles or muscle groups of variable topography (axial, proximal limb, distal). Myoclonus is less regularly repetitive and less sustained than is clonus. Evidence: TAS. (OMIM:611726)
- Hypoplasia of the corpus callosum (HP:0002079): Underdevelopment of the corpus callosum. Evidence: PCS. Frequency: 1/2. (PMID:22748208)
- Developmental regression (HP:0002376): Loss of developmental skills, as manifested by loss of developmental milestones. Evidence: PCS. Frequency: 2/2. Onset: Childhood onset (HP:0011463). (PMID:22748208)
- Cerebellar atrophy (HP:0001272): Cerebellar atrophy is defined as a cerebellum with initially normal structures, in a posterior fossa with normal size, which displays enlarged fissures (interfolial spaces) in comparison to the foliae secondary to loss of tissue. Cerebellar atrophy implies irreversible loss of tissue and result from an ongoing progressive disease until a final stage is reached or a single injury, e.g. an intoxication or infectious event. Evidence: PCS. Frequency: 2/2. (PMID:22748208)
- Dysarthria (HP:0001260): Dysarthric speech is a general description referring to a neurological speech disorder characterized by poor articulation. Depending on the involved neurological structures, dysarthria may be further classified as spastic, flaccid, ataxic, hyperkinetic and hypokinetic, or mixed. Evidence: PCS. Frequency: 3/3. (PMID:17455289)
- Infantile onset (HP:0003593): Onset of signs or symptoms of disease between 28 days to one year of life. Evidence: PCS. Frequency: 2/2. (PMID:22748208)
- Myoclonic seizure (HP:0032794): A myoclonic seizure is a type of motor seizure characterized by sudden, brief (<100 ms) involuntary single or multiple contraction of muscles or muscle groups of variable topography (axial, proximal limb, distal). Myoclonus is less regularly repetitive and less sustained than is clonus. Evidence: PCS. (PMID:17455289)
- Myoclonic status epilepticus (HP:0032667): A type of motor status epilepticus with repeating bilateral sudden brief (less than 100 ms) involuntary single or multiple contraction of muscles or muscle groups of variable topography. Evidence: PCS. Frequency: 1/3. (PMID:17455289)
- Autosomal recessive inheritance (HP:0000007): A mode of inheritance that is observed for traits related to a gene encoded on one of the autosomes (i.e., the human chromosomes 1-22) in which a trait manifests in individuals with two pathogenic alleles, either homozygotes (two copies of the same mutant allele) or compound heterozygotes (whereby each copy of a gene has a distinct mutant allele). Evidence: PCS. (PMID:17455289)
- Fingerprint intracellular accumulation of autofluorescent lipopigment storage material (HP:0003208): An intracellular accumulation of autofluorescent lipopigment storage material in a trabecular or fingerprint-like pattern. Evidence: TAS. (OMIM:611726)
- Optic atrophy (HP:0000648): Atrophy of the optic nerve. Optic atrophy results from the death of the retinal ganglion cell axons that comprise the optic nerve and manifesting as a pale optic nerve on fundoscopy. Evidence: PCS. Frequency: 1/2. (PMID:22748208)
- Bilateral tonic-clonic seizure with focal onset (HP:0007334): A bilateral tonic-clonic seizure with focal onset is a focal-onset seizure which progresses into a bilateral tonic-clonic phase. Evidence: PCS. Frequency: 2/3. (PMID:17455289)
- Intellectual disability (HP:0001249): The term intellectual disability or intellectual developmental disorder is used to describe significantly sub-average intellectual and adaptive functioning based on clinical assessment and as measured by individually administered, appropriately normed, standardized and validated tests of intellectual functioning and adaptive behavior, with onset during the developmental period from infancy through adolescence. Evidence: PCS. Frequency: 3/3. (PMID:17455289)
These phenotypes are associated with the disease progressive myoclonic epilepsy type 3 (OMIM:611726).