- Poor speech (HP:0002465). Evidence: PCS. (PMID:19525954)
- Microcephaly (HP:0000252): Head circumference below 2 standard deviations below the mean for age and gender. Evidence: PCS. Frequency: 2/7. (PMID:19525954)
- Delayed speech and language development (HP:0000750): A degree of language development that is significantly below the norm for a child of a specified age. Evidence: PCS. Frequency: 7/7. (PMID:19525954)
- Dystonia (HP:0001332): An abnormally increased muscular tone that causes fixed abnormal postures. There is a slow, intermittent twisting motion that leads to exaggerated turning and posture of the extremities and trunk. Evidence: PCS. Frequency: 1/7. (PMID:19525954)
- Seizure (HP:0001250): A seizure is an intermittent abnormality of nervous system physiology characterized by a transient occurrence of signs and/or symptoms due to abnormal excessive or synchronous neuronal activity in the brain. Evidence: PCS. Frequency: 5/7. (PMID:19525954)
- Leukoencephalopathy (HP:0002352): This term describes abnormality of the white matter of the cerebrum resulting from damage to the myelin sheaths of nerve cells. Evidence: IEA. Frequency: Occasional (HP:0040283). (OMIM:612951)
- Doll-like facies (HP:0000295): A characteristic facial appearance with a round facial form, full cheeks, a short nose, and a relatively small chin. Evidence: IEA. Frequency: Occasional (HP:0040283). (OMIM:612951)
- Global developmental delay (HP:0001263): A delay in the achievement of motor or mental milestones in the domains of development of a child, including motor skills, speech and language, cognitive skills, and social and emotional skills. This term should only be used to describe children younger than five years of age. Evidence: PCS. Frequency: 7/7. (PMID:19525954)
- Ataxia (HP:0001251): Ataxia refers to impaired coordination of voluntary muscle movement. Cerebellar ataxia refers to ataxia due to dysfunction of the cerebellum. This causes a variety of elementary neurological deficits including asynergy (lack of coordination between muscles, limbs and joints), dysmetria (lack of ability to judge distances that can lead to under- or overshoot in grasping movements), and dysdiadochokinesia (inability to perform rapid movements requiring antagonizing muscle groups to be switched on and off repeatedly). Evidence: IEA. Frequency: Occasional (HP:0040283). (OMIM:612951)
- Infantile onset (HP:0003593): Onset of signs or symptoms of disease between 28 days to one year of life. Evidence: PCS. Frequency: 7/7. (PMID:19525954)
- Abnormal CNS myelination (HP:0011400): An abnormality of myelination of nerves in the central nervous system. Evidence: IEA. Frequency: Occasional (HP:0040283). (OMIM:612951)
- Severe global developmental delay (HP:0011344): A severe delay in the achievement of motor or mental milestones in the domains of development of a child. Evidence: IEA. Frequency: Occasional (HP:0040283). (OMIM:612951)
- Focal white matter lesions (HP:0007042). Evidence: TAS. (OMIM:612951)
- Nystagmus (HP:0000639): Rhythmic, involuntary oscillations of one or both eyes related to abnormality in fixation, conjugate gaze, or vestibular mechanisms. Evidence: IEA. Frequency: Occasional (HP:0040283). (OMIM:612951)
- Sensorineural hearing impairment (HP:0000407): A type of hearing impairment in one or both ears related to an abnormal functionality of the cochlear nerve. Evidence: IEA. Frequency: Occasional (HP:0040283). (OMIM:612951)
- 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:19525954)
- Ventriculomegaly (HP:0002119): An increase in size of the ventricular system of the brain. Evidence: IEA. Frequency: Occasional (HP:0040283). (OMIM:612951)
- Athetosis (HP:0002305): A slow, continuous, involuntary writhing movement that prevents maintenance of a stable posture. Athetosis involves continuous smooth movements that appear random and are not composed of recognizable sub-movements or movement fragments. In contrast to chorea, in athetosis, the same regions of the body are repeatedly involved. Athetosis may worsen with attempts at movement of posture, but athetosis can also occur at rest. Evidence: IEA. Frequency: Occasional (HP:0040283). (OMIM:612951)
- Cerebral calcification (HP:0002514): The presence of calcium deposition within the cerebrum. Evidence: IEA. Frequency: Occasional (HP:0040283). (OMIM:612951)
- Spasticity (HP:0001257): A motor disorder characterized by a velocity-dependent increase in tonic stretch reflexes with increased muscle tone, exaggerated (hyperexcitable) tendon reflexes. Evidence: PCS. Frequency: 6/7. (PMID:19525954)
- Slowly progressive (HP:0003677): Applies to a disease manifestation that only slowly increases in scope or severity over the course of time. Evidence: TAS. (OMIM:612951)
These phenotypes are associated with the disease cystic leukoencephalopathy without megalencephaly (OMIM:612951).