- Decreased body weight (HP:0004325): Abnormally low body weight. Evidence: TAS. (OMIM:300243)
- Hyperkinetic movements (HP:0002487): Motor hyperactivity with excessive movement of muscles of the body as a whole. Evidence: PCS. Frequency: 5/11. (PMID:18342287)
- Mutism (HP:0002300): Complete lack of speech or verbal communication in a person despite attempts to engage in conversation. Mutism as a phenomena assumes the individual has previous capacity for speech and in the pediatric population it assumes that the person is past the age of typical language development. Evidence: IEA. (OMIM:300243)
- Strabismus (HP:0000486): A misalignment of the eyes so that the visual axes deviate from bifoveal fixation. The classification of strabismus may be based on a number of features including the relative position of the eyes, whether the deviation is latent or manifest, intermittent or constant, concomitant or otherwise and according to the age of onset and the relevance of any associated refractive error. Evidence: PCS. Frequency: 11/11. (PMID:18342287)
- 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: 3/7. (PMID:18342287)
- Flexion contracture (HP:0001371): A flexion contracture is a bent (flexed) joint that cannot be straightened actively or passively. It is thus a chronic loss of joint motion due to structural changes in muscle, tendons, ligaments, or skin that prevents normal movement of joints. Evidence: IEA. (OMIM:300243)
- 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: 11/11. (PMID:18342287)
- Hypotonia (HP:0001252): Hypotonia is an abnormally low muscle tone (the amount of tension or resistance to movement in a muscle). Even when relaxed, muscles have a continuous and passive partial contraction which provides some resistance to passive stretching. Hypotonia thus manifests as diminished resistance to passive stretching. Hypotonia is not the same as muscle weakness, although the two conditions can co-exist. Evidence: TAS. (OMIM:300243)
- Sleep disturbance (HP:0002360): An abnormal pattern in the quality, quantity, or characteristics of sleep. Evidence: PCS. Frequency: 2/7. (PMID:18342287)
- Urinary incontinence (HP:0000020): Loss of the ability to control the urinary bladder leading to involuntary urination. Evidence: IEA. (OMIM:300243)
- 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: PCS. Frequency: 11/11. (PMID:18342287)
- Generalized hypotonia (HP:0001290): Generalized muscular hypotonia (abnormally low muscle tone). Evidence: TAS. (OMIM:300243)
- Happy demeanor (HP:0040082): A conspicuously happy disposition, characterized by frequent smiling and laughing, which may be contextually inappropriate or unrelated to the situation. Evidence: PCS. (PMID:18342287)
- Severe intellectual disability (HP:0010864): Severe intellectual disability (ID) is defined as a type of ID characterized by severely sub-average adaptive functioning and intellectual functioning, with an intelligence quotient (IQ) the range of 20-34. Evidence: TAS. (OMIM:300243)
- Interictal epileptiform activity (HP:0011182): Epileptiform activity refers to distinctive EEG waves or complexes distinguished from background activity found in in a proportion of human subjects with epilepsy, but which can also be found in subjects without seizures. Interictal epileptiform activity refers to such activity that occurs in the absence of a clinical or subclinical seizure. Evidence: PCS. Frequency: 11/11. (PMID:18342287)
- Loss of ability to walk in first decade (HP:0006794). Evidence: IEA. (OMIM:300243)
- Narrow chest (HP:0000774): Reduced width of the chest from side to side, associated with a reduced distance from the sternal notch to the tip of the shoulder. Evidence: IEA. (OMIM:300243)
- 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: IEA. (OMIM:300243)
- Photosensitive tonic-clonic seizure (HP:0007207): Generalized-onset tonic-clonic seizures that are provoked by flashing or flickering light. Evidence: IEA. (OMIM:300243)
- Abnormal foot morphology (HP:0001760): An abnormality of the skeleton of foot. Evidence: IEA. (OMIM:300243)
- Narrow face (HP:0000275): Bizygomatic (upper face) and bigonial (lower face) width are both more than 2 standard deviations below the mean (objective); or, an apparent reduction in the width of the upper and lower face (subjective). Evidence: TAS. (OMIM:300243)
- Skeletal muscle atrophy (HP:0003202): The presence of skeletal muscular atrophy (which is also known as amyotrophy). Evidence: IEA. (OMIM:300243)
- Dysphagia (HP:0002015): Difficulty in swallowing. Evidence: PCS. Frequency: 5/11. (PMID:18342287)
- Microcephaly (HP:0000252): Head circumference below 2 standard deviations below the mean for age and gender. Evidence: PCS. Frequency: 10/11. (PMID:18342287)
- Absent speech (HP:0001344): Complete lack of development of speech and language abilities. Evidence: PCS. Frequency: 11/11. (PMID:18342287)
- Long nose (HP:0003189): Distance from nasion to subnasale more than two standard deviations above the mean, or alternatively, an apparently increased length from the nasal root to the nasal base. Evidence: TAS. (OMIM:300243)
- Thick eyebrow (HP:0000574): Increased density/number and/or increased diameter of eyebrow hairs. Evidence: IEA. (OMIM:300243)
- Truncal ataxia (HP:0002078): Truncal ataxia is a sign of ataxia characterized by instability of the trunk. It usually occurs during sitting. Evidence: IEA. (OMIM:300243)
- Long face (HP:0000276): Facial height (length) is more than 2 standard deviations above the mean (objective); or, an apparent increase in the height (length) of the face (subjective). Evidence: TAS. (OMIM:300243)
- Open mouth (HP:0000194): A facial appearance characterized by a permanently or nearly permanently opened mouth. Evidence: PCS. Frequency: 6/7. (PMID:18342287)
- 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: 11/11. (PMID:18342287)
- Adducted thumb (HP:0001181): In the resting position, the tip of the thumb is on, or near, the palm, close to the base of the fourth or fifth finger. Evidence: IEA. (OMIM:300243)
- X-linked recessive inheritance (HP:0001419): A mode of inheritance that is observed for recessive traits related to a gene encoded on the X chromosome. In the context of medical genetics, X-linked recessive disorders manifest in males (who have one copy of the X chromosome and are thus hemizygotes), but generally not in female heterozygotes who have one mutant and one normal allele. Evidence: PCS. (PMID:18342287)
- Bowel incontinence (HP:0002607): Involuntary fecal soiling in adults and children who have usually already been toilet trained. Evidence: IEA. (OMIM:300243)
- Ophthalmoplegia (HP:0000602): Paralysis of one or more extraocular muscles that are responsible for eye movements. Evidence: IEA. (OMIM:300243)
- Neuronal loss in central nervous system (HP:0002529). Evidence: IEA. (OMIM:300243)
- Drooling (HP:0002307): Habitual flow of saliva out of the mouth. Evidence: PCS. Frequency: 6/7. (PMID:18342287)
- 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: IEA. (OMIM:300243)
- Mandibular prognathia (HP:0000303): Abnormal prominence of the chin related to increased length of the mandible. Evidence: TAS. (OMIM:300243)
- Slender finger (HP:0001238): Fingers that are disproportionately narrow (reduced girth) for the hand/foot size or build of the individual. Evidence: IEA. (OMIM:300243)
These phenotypes are associated with the disease Christianson syndrome (OMIM:300243).