- Hypertonia (HP:0001276): A condition in which there is increased muscle tone so that arms or legs, for example, are stiff and difficult to move. Evidence: PCS. Frequency: 5/5. (PMID:20950787)
- Clonus (HP:0002169): A series of rhythmic and involuntary muscle contractions (at a frequency of about 5 to 7 Hz) that occur in response to an abruptly applied and sustained stretch. Evidence: PCS. Frequency: 5/5. (PMID:20950787)
- Dysphagia (HP:0002015): Difficulty in swallowing. Evidence: PCS. Frequency: 5/5. (PMID:20950787)
- Hypsarrhythmia (HP:0002521): Hypsarrhythmia is abnormal interictal high amplitude waves and a background of irregular spikes. There is continuous (during wakefulness), high-amplitude (>200 Hz), generalized polymorphic slowing with no organized background and multifocal spikes demonstrated by electroencephalography (EEG). Evidence: PCS. Frequency: 5/5. (PMID:20950787)
- 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: PCS. (PMID:20950787)
- Delayed CNS myelination (HP:0002188): Delayed myelination in the central nervous system. Evidence: PCS. Frequency: 5/5. (PMID:20950787)
- Hypoplasia of the brainstem (HP:0002365): Underdevelopment of the brainstem. Evidence: PCS. Frequency: 5/5. (PMID:20950787)
- Feeding difficulties (HP:0011968): Impaired ability to eat related to problems gathering food and getting ready to suck, chew, or swallow it. Evidence: PCS. Frequency: 5/5. (PMID:20950787)
- 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: 5/5. (PMID:20950787)
- 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: 5/5. (PMID:20950787)
- Secondary microcephaly (HP:0005484): Head circumference which falls below 2 standard deviations below the mean for age and gender because of insufficient head growth after birth. Evidence: PCS. Frequency: 5/5. (PMID:20950787)
- Infantile onset (HP:0003593): Onset of signs or symptoms of disease between 28 days to one year of life. Evidence: PCS. Frequency: 5/5. (PMID:20950787)
- Decreased thalamic volume (HP:0012695): A reduction in the quantity of space occupied by the thalamus. Evidence: PCS. Frequency: 5/5. (PMID:20950787)
- Failure to thrive (HP:0001508): Failure to thrive (FTT) refers to a child whose physical growth is substantially below the norm. Evidence: PCS. Frequency: 5/5. (PMID:20950787)
- Diffuse cerebral atrophy (HP:0002506): Diffuse unlocalised atrophy affecting the cerebrum. Evidence: PCS. Frequency: 5/5. (PMID:20950787)
- 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:20950787)
- 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: 5/5. (PMID:20950787)
- Hyperreflexia (HP:0001347): Hyperreflexia is the presence of hyperactive stretch reflexes of the muscles. Evidence: PCS. Frequency: 5/5. (PMID:20950787)
These phenotypes are associated with the disease infantile cerebral and cerebellar atrophy with postnatal progressive microcephaly (OMIM:613668).