- Microcephaly (HP:0000252): Head circumference below 2 standard deviations below the mean for age and gender. Evidence: TAS. Frequency: Frequent (HP:0040282). (ORPHA:85165)
- Abnormal clavicle morphology (HP:0000889): Any abnormality of the clavicles (collar bones). Evidence: TAS. Frequency: Frequent (HP:0040282). (ORPHA:85165)
- Acanthosis nigricans (HP:0000956): A dermatosis characterized by thickened, hyperpigmented plaques, typically on the intertriginous surfaces and neck. Evidence: TAS. Frequency: Very frequent (HP:0040281). (ORPHA:85165)
- Hypoplasia of the corpus callosum (HP:0002079): Underdevelopment of the corpus callosum. Evidence: TAS. Frequency: Very frequent (HP:0040281). (ORPHA:85165)
- Generalized-onset seizure (HP:0002197): A generalized-onset seizure is a type of seizure originating at some point within, and rapidly engaging, bilaterally distributed networks. The networks may include cortical and subcortical structures but not necessarily the entire cortex. Evidence: TAS. Frequency: Very frequent (HP:0040281). (ORPHA:85165)
- Femoral bowing (HP:0002980): Bowing (abnormal curvature) of the femur. Evidence: TAS. Frequency: Frequent (HP:0040282). (ORPHA:85165)
- Tibial bowing (HP:0002982): A bending or abnormal curvature of the tibia. Evidence: TAS. Frequency: Frequent (HP:0040282). (ORPHA:85165)
- Metaphyseal chondrodysplasia (HP:0005871): An abnormality of skeletal development characterized by a disturbance of the metaphysis and its histological structure with relatively normal epiphyses and vertebrae. Evidence: TAS. Frequency: Very frequent (HP:0040281). (ORPHA:85165)
- Aplasia/Hypoplasia of the mandible (HP:0009118): Absence or underdevelopment of the mandible. Evidence: TAS. Frequency: Very frequent (HP:0040281). (ORPHA:85165)
- Fibular bowing (HP:0010502): A bending or abnormal curvature of the fibula. Evidence: TAS. Frequency: Frequent (HP:0040282). (ORPHA:85165)
- 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. Frequency: Very frequent (HP:0040281). (ORPHA:85165)
- Severe global developmental delay (HP:0011344): A severe delay in the achievement of motor or mental milestones in the domains of development of a child. Evidence: TAS. Frequency: Very frequent (HP:0040281). (ORPHA:85165)
- Enlarged cerebellum (HP:0012081): An abnormally increased size of the cerebellum compared to other brain structures. Evidence: TAS. Frequency: Very frequent (HP:0040281). (ORPHA:85165)
- Brain atrophy (HP:0012444): Partial or complete wasting (loss) of brain tissue that was once present. Evidence: TAS. Frequency: Very frequent (HP:0040281). (ORPHA:85165)
These phenotypes are associated with the disease Severe achondroplasia-developmental delay-acanthosis nigricans syndrome (ORPHA:85165).