- Poor head control (HP:0002421): Difficulty to maintain correct position of the head while standing or sitting. Infant head lag is observed when the head seems to flop around or lags posteriorly behind the trunk. Several articles have maintained that head lag should be absent by age 3 to 4 months. Evidence: PCS. Frequency: 1/1. (PMID:27904971)
- Microcephaly (HP:0000252): Head circumference below 2 standard deviations below the mean for age and gender. Evidence: PCS. Frequency: 3/3. (PMID:27904971;PMID:31754459)
- Cerebral atrophy (HP:0002059): Atrophy (wasting, decrease in size of cells or tissue) affecting the cerebrum. Evidence: PCS. Frequency: 3/3. (PMID:27904971;PMID:31754459)
- Hypoplasia of the corpus callosum (HP:0002079): Underdevelopment of the corpus callosum. Evidence: PCS. Frequency: 3/3. (PMID:27904971;PMID:31754459)
- 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: 1/2. (PMID:31754459)
- 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: 1/2. (PMID:31754459)
- Episodic vomiting (HP:0002572): Paroxysmal, recurrent episodes of vomiting. Evidence: PCS. Frequency: 1/2. (PMID:31754459)
- 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: 1/1. (PMID:27904971)
- 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:31754459)
- Cerebral palsy (HP:0100021): Cerebral palsy describes a group of permanent disorders of the development of movement and posture, causing activity limitation, that are attributed to nonprogressive disturbances that occurred in the developing fetal or infant brain. The motor disorders of cerebral palsy are often accompanied by disturbances of sensation, perception, cognition, communication, and behavior, by epilepsy, and by secondary musculoskeletal problems. Evidence: PCS. Frequency: 1/1. (PMID:27904971)
- Enlarged cisterna magna (HP:0002280): Increase in size of the cisterna magna, one of three principal openings in the subarachnoid space between the arachnoid and pia mater, located between the cerebellum and the dorsal surface of the medulla oblongata. Evidence: PCS. Frequency: 1/2. (PMID:31754459)
- Hypoplasia of the pons (HP:0012110): Underdevelopment of the pons. Evidence: PCS. Frequency: 1/1. (PMID:27904971)
- Gastrostomy tube feeding in infancy (HP:0011471): Feeding problem necessitating gastrostomy tube feeding. Evidence: PCS. Frequency: 1/1. (PMID:27904971)
- Nystagmus (HP:0000639): Rhythmic, involuntary oscillations of one or both eyes related to abnormality in fixation, conjugate gaze, or vestibular mechanisms. Evidence: PCS. Frequency: 3/3. (PMID:27904971;PMID:31754459)
- Clubbing of fingers (HP:0100759): Terminal broadening of the fingers (distal phalanges of the fingers). Evidence: PCS. Frequency: 1/2. (PMID:31754459)
- Peripheral neuropathy (HP:0009830): Peripheral neuropathy is a general term for any disorder of the peripheral nervous system. The main clinical features used to classify peripheral neuropathy are distribution, type (mainly demyelinating versus mainly axonal), duration, and course. Evidence: PCS. (PMID:31754459)
- 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:27904971)
- 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: 1/2. (PMID:31754459)
- Polymicrogyria (HP:0002126): Polymicrogyria is a congenital malformation of the cerebral cortex characterized by abnormal cortical layering (lamination) and an excessive number of small gyri (folds). Evidence: PCS. Frequency: 1/1. (PMID:27904971)
- Decreased circulating IgG concentration (HP:0004315): An abnormally decreased level of immunoglobulin G (IgG) in blood. Evidence: PCS. Frequency: 2/2. (PMID:31754459)
These phenotypes are associated with the disease neurodegeneration, infantile-onset, biotin-responsive (OMIM:618973).