- 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: TAS. Frequency: Very frequent (HP:0040281). (ORPHA:59)
- Axial hypotonia (HP:0008936): Muscular hypotonia (abnormally low muscle tone) affecting the musculature of the trunk. Evidence: TAS. Frequency: Very frequent (HP:0040281). (ORPHA:59)
- 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. Frequency: Frequent (HP:0040282). (ORPHA:59)
- 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. Frequency: Frequent (HP:0040282). (ORPHA:59)
- 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: TAS. Frequency: Frequent (HP:0040282). (ORPHA:59)
- Pectus excavatum (HP:0000767): A defect of the chest wall characterized by a depression of the sternum, giving the chest ("pectus") a caved-in ("excavatum") appearance. Evidence: TAS. Frequency: Frequent (HP:0040282). (ORPHA:59)
- Hypertension (HP:0000822): The presence of chronic increased pressure in the systemic arterial system. Evidence: TAS. Frequency: Frequent (HP:0040282). (ORPHA:59)
- Hyperhidrosis (HP:0000975): Abnormal excessive perspiration (sweating) despite the lack of appropriate stimuli like hot and humid weather. Evidence: TAS. Frequency: Frequent (HP:0040282). (ORPHA:59)
- 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: TAS. Frequency: Frequent (HP:0040282). (ORPHA:59)
- 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: TAS. Frequency: Frequent (HP:0040282). (ORPHA:59)
- Choreoathetosis (HP:0001266): Involuntary movements characterized by both athetosis (inability to sustain muscles in a fixed position) and chorea (widespread jerky arrhythmic movements). Evidence: TAS. Frequency: Frequent (HP:0040282). (ORPHA:59)
- 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: TAS. Frequency: Frequent (HP:0040282). (ORPHA:59)
- Hyperreflexia (HP:0001347): Hyperreflexia is the presence of hyperactive stretch reflexes of the muscles. Evidence: TAS. Frequency: Frequent (HP:0040282). (ORPHA:59)
- Failure to thrive in infancy (HP:0001531). Evidence: TAS. Frequency: Frequent (HP:0040282). (ORPHA:59)
- Tachycardia (HP:0001649): A rapid heartrate that exceeds the range of the normal resting heartrate for age. Evidence: TAS. Frequency: Frequent (HP:0040282). (ORPHA:59)
- Pes planus (HP:0001763): A foot where the longitudinal arch of the foot is in contact with the ground or floor when the individual is standing; or, in a patient lying supine, a foot where the arch is in contact with the surface of a flat board pressed against the sole of the foot by the examiner with a pressure similar to that expected from weight bearing; or, the height of the arch is reduced. Evidence: TAS. Frequency: Frequent (HP:0040282). (ORPHA:59)
- Myopathic facies (HP:0002058): A facial appearance characteristic of myopathic conditions. The face appears expressionless with sunken cheeks, bilateral ptosis, and inability to elevate the corners of the mouth, due to muscle weakness. Evidence: TAS. Frequency: Frequent (HP:0040282). (ORPHA:59)
- Recurrent respiratory infections (HP:0002205): An increased susceptibility to respiratory infections as manifested by a history of recurrent respiratory infections. Evidence: TAS. Frequency: Frequent (HP:0040282). (ORPHA:59)
- Sleep disturbance (HP:0002360): An abnormal pattern in the quality, quantity, or characteristics of sleep. Evidence: TAS. Frequency: Frequent (HP:0040282). (ORPHA:59)
- Hypokinesia (HP:0002375): Abnormally diminished motor activity. In contrast to paralysis, hypokinesia is not characterized by a lack of motor strength, but rather by a poverty of movement. The typical habitual movements (e.g., folding the arms, crossing the legs) are reduced in frequency. Evidence: TAS. Frequency: Frequent (HP:0040282). (ORPHA:59)
- Kyphoscoliosis (HP:0002751): An abnormal curvature of the spine in both a coronal (lateral) and sagittal (back-to-front) plane. Evidence: TAS. Frequency: Frequent (HP:0040282). (ORPHA:59)
- Abnormality of thyroid physiology (HP:0002926): An abnormal functionality of the thyroid gland. Evidence: TAS. Frequency: Frequent (HP:0040282). (ORPHA:59)
- Skeletal muscle atrophy (HP:0003202): The presence of skeletal muscular atrophy (which is also known as amyotrophy). Evidence: TAS. Frequency: Frequent (HP:0040282). (ORPHA:59)
- Abnormal pyramidal sign (HP:0007256): Functional neurological abnormalities related to dysfunction of the pyramidal tract. Evidence: TAS. Frequency: Frequent (HP:0040282). (ORPHA:59)
- Pes valgus (HP:0008081): An outward (valgus) deviation of the calcaneus relative to the longitudinal axis of the lower leg at the talocalcaneal (subtalar) joint, such that the heel is everted. Evidence: TAS. Frequency: Frequent (HP:0040282). (ORPHA:59)
- Feeding difficulties in infancy (HP:0008872): Impaired feeding performance of an infant as manifested by difficulties such as weak and ineffective sucking, brief bursts of sucking, and falling asleep during sucking. There may be difficulties with chewing or maintaining attention. Evidence: TAS. Frequency: Frequent (HP:0040282). (ORPHA:59)
- Increased circulating free T3 (HP:0011788): An elevated concentration of free 3,3',5-triiodo-L-thyronine in the blood circulation. Evidence: TAS. Frequency: Frequent (HP:0040282). (ORPHA:59)
- Brain atrophy (HP:0012444): Partial or complete wasting (loss) of brain tissue that was once present. Evidence: TAS. Frequency: Frequent (HP:0040282). (ORPHA:59)
- Delayed myelination (HP:0012448): Delayed myelination. Evidence: TAS. Frequency: Frequent (HP:0040282). (ORPHA:59)
- Delayed ability to walk (HP:0031936): A failure to achieve the ability to walk at an appropriate developmental stage. Most children learn to walk in a series of stages, and learn to walk short distances independently between 12 and 15 months. Evidence: TAS. Frequency: Frequent (HP:0040282). (ORPHA:59)
- Decreased body mass index (HP:0045082): Abnormally decreased weight-to-height squared ratio, calculated by dividing the individual's weight in kilograms by the square of the individual's height in meters and used as an indicator of underweight compared to averages. Evidence: TAS. Frequency: Frequent (HP:0040282). (ORPHA:59)
- Cryptorchidism (HP:0000028): Testis in inguinal canal. That is, absence of one or both testes from the scrotum owing to failure of the testis or testes to descend through the inguinal canal to the scrotum. Evidence: TAS. Frequency: Occasional (HP:0040283). (ORPHA:59)
- Microcephaly (HP:0000252): Head circumference below 2 standard deviations below the mean for age and gender. Evidence: TAS. Frequency: Occasional (HP:0040283). (ORPHA:59)
- Nystagmus (HP:0000639): Rhythmic, involuntary oscillations of one or both eyes related to abnormality in fixation, conjugate gaze, or vestibular mechanisms. Evidence: TAS. Frequency: Occasional (HP:0040283). (ORPHA:59)
- 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: TAS. Frequency: Occasional (HP:0040283). (ORPHA:59)
- Neonatal hypotonia (HP:0001319): Muscular hypotonia (abnormally low muscle tone) manifesting in the neonatal period. Evidence: TAS. Frequency: Occasional (HP:0040283). (ORPHA:59)
- Brisk reflexes (HP:0001348): Tendon reflexes that are noticeably more active than usual (conventionally denoted 3+ on clinical examination). Brisk reflexes may or may not indicate a neurological lesion. They are distinguished from hyperreflexia by the fact that hyerreflexia is characterized by hyperactive repeating (clonic) reflexes, which are considered to be always abnormal. Evidence: TAS. Frequency: Occasional (HP:0040283). (ORPHA:59)
- 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: TAS. Frequency: Occasional (HP:0040283). (ORPHA:59)
- Decreased fetal movement (HP:0001558): An abnormal reduction in quantity or strength of fetal movements. Evidence: TAS. Frequency: Occasional (HP:0040283). (ORPHA:59)
- Abnormality of extrapyramidal motor function (HP:0002071): A neurological condition related to lesions of the basal ganglia leading to typical abnormalities including akinesia (inability to initiate changes in activity and perform volitional movements rapidly and easily), muscular rigidity (continuous contraction of muscles with constant resistance to passive movement), chorea (widespread arrhythmic movements of a forcible, rapid, jerky, and restless nature), athetosis (inability to sustain the muscles of the fingers, toes, or other group of muscles in a fixed position), and akathisia (inability to remain motionless). Evidence: TAS. Frequency: Occasional (HP:0040283). (ORPHA:59)
- Moderate intellectual disability (HP:0002342): Moderate intellectual disability (ID) is defined as a type of ID characterized by moderately sub-average adaptive functioning and intellectual functioning, with an intelligence quotient (IQ) the range of 35-49. Evidence: TAS. Frequency: Occasional (HP:0040283). (ORPHA:59)
- 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: TAS. Frequency: Occasional (HP:0040283). (ORPHA:59)
- Limb hypertonia (HP:0002509). Evidence: TAS. Frequency: Occasional (HP:0040283). (ORPHA:59)
- Spastic tetraplegia (HP:0002510): Spastic paralysis affecting all four limbs. Evidence: TAS. Frequency: Occasional (HP:0040283). (ORPHA:59)
- Generalized muscle weakness (HP:0003324): Generalized weakness or decreased strength of the muscles, affecting both distal and proximal musculature. Evidence: TAS. Frequency: Occasional (HP:0040283). (ORPHA:59)
- Babinski sign (HP:0003487): Upturning of the big toe (and sometimes fanning of the other toes) in response to stimulation of the sole of the foot. If the Babinski sign is present it can indicate damage to the corticospinal tract. Evidence: TAS. Frequency: Occasional (HP:0040283). (ORPHA:59)
- Short stature (HP:0004322): A height below that which is expected according to age and gender norms. Although there is no universally accepted definition of short stature, many refer to "short stature" as height more than 2 standard deviations below the mean for age and gender (or below the 3rd percentile for age and gender dependent norms). Evidence: TAS. Frequency: Occasional (HP:0040283). (ORPHA:59)
- Prolonged neonatal jaundice (HP:0006579): Neonatal jaundice refers to a yellowing of the skin and other tissues of a newborn infant as a result of increased concentrations of bilirubin in the blood. Neonatal jaundice affects over half of all newborns to some extent in the first week of life. Prolonged neonatal jaundice is said to be present if the jaundice persists for longer than 14 days in term infants and 21 days in preterm infants. Evidence: TAS. Frequency: Occasional (HP:0040283). (ORPHA:59)
- Ankle clonus (HP:0011448): Clonus is an involuntary tendon reflex that causes repeated flexion and extension of the foot. Ankle clonus is tested by rapidly flexing the foot upward. Evidence: TAS. Frequency: Occasional (HP:0040283). (ORPHA:59)
- Small for gestational age (HP:0001518): Smaller than normal size according to sex and gestational age related norms, defined as a weight below the 10th percentile for the gestational age. Evidence: TAS. Frequency: Very rare (HP:0040284). (ORPHA:59)
- Polyhydramnios (HP:0001561): The presence of excess amniotic fluid in the uterus during pregnancy. Evidence: TAS. Frequency: Very rare (HP:0040284). (ORPHA:59)
- Premature birth (HP:0001622): The birth of a baby of less than 37 weeks of gestational age. Evidence: TAS. Frequency: Very rare (HP:0040284). (ORPHA:59)
- Macrocephaly at birth (HP:0004488): The presence of an abnormally large skull with onset at birth. Evidence: TAS. Frequency: Very rare (HP:0040284). (ORPHA:59)
- Dyskinesia (HP:0100660): A movement disorder which consists of effects including diminished voluntary movements and the presence of involuntary movements. Evidence: TAS. Frequency: Very rare (HP:0040284). (ORPHA:59)
These phenotypes are associated with the disease Allan-Herndon-Dudley syndrome (ORPHA:59).