- 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: 4/5. (PMID:33397746)
- 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: 4/5. (PMID:33397746)
- Bilateral tonic-clonic seizure (HP:0002069): A bilateral tonic-clonic seizure is a seizure defined by a tonic (bilateral increased tone, lasting seconds to minutes) and then a clonic (bilateral sustained rhythmic jerking) phase. Evidence: PCS. Frequency: 1/5. (PMID:33397746)
- Sloping forehead (HP:0000340): Inclination of the anterior surface of the forehead from the vertical more than two standard deviations above the mean (objective); or apparently excessive posterior sloping of the forehead in a lateral view. Evidence: PCS. Frequency: 4/5. (PMID:33397746)
- Upslanted palpebral fissure (HP:0000582): The palpebral fissure inclination is more than two standard deviations above the mean for age (objective); or, the inclination of the palpebral fissure is greater than typical for age. Evidence: PCS. Frequency: 3/5. (PMID:33397746)
- 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: 1/5. (PMID:33397746)
- Hearing impairment (HP:0000365): A decreased magnitude of the sensory perception of sound. Evidence: PCS. Frequency: 2/5. (PMID:33397746)
- Inability to walk (HP:0002540): Incapability to ambulate. Evidence: PCS. Frequency: 3/5. (PMID:33397746)
- Delayed CNS myelination (HP:0002188): Delayed myelination in the central nervous system. Evidence: PCS. Frequency: 3/5. (PMID:33397746)
- Infantile onset (HP:0003593): Onset of signs or symptoms of disease between 28 days to one year of life. Evidence: PCS. Frequency: 1/5. (PMID:33397746)
- 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. Frequency: 3/5. (PMID:33397746)
- Thin corpus callosum (HP:0033725): An abnormally thin corpus callous, due to atrophy, hypoplasia or agenesis. This term is intended to be used in situations where it is not known if thinning of the corpus callosum (for instance, as visualized by magnetic resonance tomography) is due to abnormal development (e.g. a leukodystrophy) or atrophy following normal development (e.g. neurodegeneration). Evidence: PCS. Frequency: 3/5. (PMID:33397746)
- Cataract (HP:0000518): A cataract is an opacity or clouding that develops in the crystalline lens of the eye or in its capsule. Evidence: PCS. Frequency: 5/5. (PMID:33397746)
- Fetal onset (HP:0011461): Onset prior to birth but after 8 weeks of embryonic development (corresponding to a gestational age of 10 weeks). Evidence: PCS. Frequency: 4/5. (PMID:33397746)
- Hypertelorism (HP:0000316): Interpupillary distance more than 2 SD above the mean (alternatively, the appearance of an increased interpupillary distance or widely spaced eyes). Evidence: PCS. Frequency: 1/5. (PMID:33397746)
- Motor stereotypy (HP:0000733): Use of the same abnormal action in response to certain triggers or at random. They may be used as a way to regulate one's internal state but must otherwise have no apparent functional purpose. Evidence: PCS. Frequency: 1/3. (PMID:33397746)
- Thin upper lip vermilion (HP:0000219): Height of the vermilion of the upper lip in the midline more than 2 SD below the mean. Alternatively, an apparently reduced height of the vermilion of the upper lip in the frontal view (subjective). Evidence: PCS. Frequency: 1/5. (PMID:33397746)
- Wide mouth (HP:0000154): Distance between the oral commissures more than 2 SD above the mean. Alternatively, an apparently increased width of the oral aperture (subjective). Evidence: PCS. Frequency: 1/5. (PMID:33397746)
- Axial hypotonia (HP:0008936): Muscular hypotonia (abnormally low muscle tone) affecting the musculature of the trunk. Evidence: PCS. Frequency: 5/5. (PMID:33397746)
- Microcephaly (HP:0000252): Head circumference below 2 standard deviations below the mean for age and gender. Evidence: PCS. Frequency: 5/5. (PMID:33397746)
- Profound global developmental delay (HP:0012736): A profound delay in the achievement of motor or mental milestones in the domains of development of a child. Evidence: PCS. Frequency: 5/5. (PMID:33397746)
- Epileptic spasm (HP:0011097): A sudden flexion, extension, or mixed extension-flexion of predominantly proximal and truncal muscles that is usually more sustained than a myoclonic movement but not as sustained as a tonic seizure. Limited forms may occur: Grimacing, head nodding, or subtle eye movements. Epileptic spasms frequently occur in clusters. Infantile spasms are the best known form, but spasms can occur at all ages. Evidence: PCS. Frequency: 2/5. (PMID:33397746)
- Precocious puberty (HP:0000826): The onset of secondary sexual characteristics before a normal age. Although it is difficult to define normal age ranges because of the marked variation with which puberty begins in normal children, precocious puberty can be defined as the onset of puberty before the age of 8 years in girls or 9 years in boys. Evidence: PCS. Frequency: 1/5. (PMID:33397746)
- Prominent nasal bridge (HP:0000426): Anterior positioning of the nasal root in comparison to the usual positioning for age. Evidence: PCS. Frequency: 1/5. (PMID:33397746)
- 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:33397746)
- Pointed chin (HP:0000307): A marked tapering of the lower face to the chin. Evidence: PCS. Frequency: 1/5. (PMID:33397746)
- Macrotia (HP:0000400): Median longitudinal ear length greater than two standard deviations above the mean and median ear width greater than two standard deviations above the mean (objective); or, apparent increase in length and width of the pinna (subjective). Evidence: PCS. Frequency: 4/5. (PMID:33397746)
- Widely spaced teeth (HP:0000687): Increased spaces (diastemata) between most of the teeth in the same dental arch. Evidence: PCS. Frequency: 1/5. (PMID:33397746)
- Simplified gyral pattern (HP:0009879): An abnormality of the cerebral cortex with fewer gyri but with normal cortical thickness. This pattern is usually often associated with congenital microcephaly. Evidence: PCS. Frequency: 3/5. (PMID:33397746)
These phenotypes are associated with the disease Dentici-Novelli neurodevelopmental syndrome (OMIM:619877).