- Flared metaphysis (HP:0003015): The presence of a splayed (i.e.,flared) metaphyseal segment of one or more long bones. Evidence: PCS. Frequency: 1/1. (PMID:16411219)
- Floppy infant (HP:0008947): Floppiness/hypotonia is defined as reduced resistance to passive movement of joints. Physical examination of floppy/hypotonic infants shows head lag, lack of shoulder and elbow muscle contraction on traction response, inability to tighten the shoulder girdle muscles (or slipping through) when held under the axillae, scarf sign (when the arm is pulled to the opposite side, the arm wraps around the neck with the elbow crossing midline), hyperdorsiflexion of the feet, easy apposition of the thumb against the forearm, feet touching the cheek with ease and without discomfort, frog leg position, and inverted U sign on ventral suspension (head, arms, and legs hanging down without elbow or knee flexion and the trunk rounded in a dome shape). Evidence: IEA. (OMIM:100800)
- Spinal stenosis with reduced interpedicular distance (HP:0005733): An abnormal narrowing of the spinal canal related to a reduction in the interpedicular distance (i.e., the distance measured between the pedicles on frontal [coronal] imaging). Evidence: IEA. (OMIM:100800)
- Congenital onset (HP:0003577): A phenotypic abnormality that is present at birth. Evidence: PCS. Frequency: 1/1. (PMID:16411219)
- Femoral bowing (HP:0002980): Bowing (abnormal curvature) of the femur. Evidence: PCS. Frequency: 1/1. (PMID:16411219)
- Limited elbow extension (HP:0001377): Limited ability to straighten the arm at the elbow joint. Evidence: TAS. (OMIM:100800)
- Megalencephaly (HP:0001355): Diffuse enlargement of the entire cerebral hemispheres leading to macrocephaly (with or without overlying cortical dysplasia). Evidence: IEA. (OMIM:100800)
- Pulmonary hypoplasia (HP:0002089). Evidence: PCS. Frequency: 1/1. (PMID:16411219)
- Rhizomelia (HP:0008905): Disproportionate shortening of the proximal segment of limbs (i.e. the femur and humerus). Evidence: PCS. Frequency: 1/1. (PMID:16411219)
- Severe platyspondyly (HP:0004565). Evidence: PCS. Frequency: 1/1. (PMID:16411219)
- Brachydactyly (HP:0001156): Digits that appear disproportionately short compared to the hand/foot. The word brachydactyly is used here to describe a series distinct patterns of shortened digits (brachydactyly types A-E). This is the sense used here. Evidence: IEA. (OMIM:100800)
- Generalized joint hypermobility (HP:0002761): Joint hypermobility (ability of a joint to move beyond its normal range of motion) affecting many or all joints of the body. In individuals with Joint hypermobility at multiple sites (usually five or more), the term generalized joint hypermobility is preferred. Evidence: IEA. (OMIM:100800)
- Thoracic hypoplasia (HP:0005257). Evidence: PCS. Frequency: 1/1. (PMID:16411219)
- Narrow greater sciatic notch (HP:0003375): A narrowing of the sacrosciatic notch, i.e., the deep indentation in the posterior border of the hip bone at the point of union of the ilium and ischium. Evidence: PCS. Frequency: 1/1. (PMID:16411219)
- Upper airway obstruction (HP:0002781): Increased resistance to the passage of air in the upper airway. Evidence: IEA. (OMIM:100800)
- Short femur (HP:0003097): An abnormal shortening of the femur. Evidence: PCS. Frequency: 1/1. (PMID:16411219)
- Ulnar bowing (HP:0003031): Bending of the diaphysis (shaft) of the ulna. Evidence: PCS. Frequency: 1/1. (PMID:16411219)
- Limited hip extension (HP:0003093): Limitation of the extension of the hip, i.e., decreased ability to straighten the hip joint and thereby increase the angle between torso and thigh; moving the thigh or top of the pelvis backward. Evidence: TAS. (OMIM:100800)
- Motor delay (HP:0001270): A type of Developmental delay characterized by a delay in acquiring motor skills. Evidence: IEA. (OMIM:100800)
- Trident hand (HP:0004060): A hand in which the fingers are of nearly equal length and deflected at the first interphalangeal joint, so as to give a forklike shape consisting of separation of the first and second as well as the third and fourth digits. Evidence: PCS. Frequency: 1/1. (PMID:16411219)
- Short femoral neck (HP:0100864): An abnormally short femoral neck (which is the process of bone, connecting the femoral head with the femoral shaft). Evidence: IEA. (OMIM:100800)
- Narrow vertebral interpedicular distance (HP:0008450): A reduction of the distance between vertebral pedicles, which are the two short, thick processes, which project backward, one on either side, from the upper part of the vertebral body, at the junction of its posterior and lateral surfaces. Evidence: PCS. Frequency: 1/1. (PMID:16411219)
- Lumbar hyperlordosis (HP:0002938): An abnormal accentuation of the inward curvature of the spine in the lumbar region. Evidence: IEA. (OMIM:100800)
- Bowing of the legs (HP:0002979): A bending or abnormal curvature affecting a long bone of the leg. Evidence: PCS. Frequency: 1/1. (PMID:16411219)
- Hydrocephalus (HP:0000238): Hydrocephalus is an active distension of the ventricular system of the brain resulting from inadequate passage of CSF from its point of production within the cerebral ventricles to its point of absorption into the systemic circulation. Evidence: PCS. Frequency: 1/1. (PMID:16411219)
- Death in infancy (HP:0001522): Death within the first 24 months of life. Evidence: PCS. Frequency: 1/1. (PMID:16411219)
- Lumbar kyphosis in infancy (HP:0008414). Evidence: IEA. (OMIM:100800)
- Macrocephaly (HP:0000256): Occipitofrontal (head) circumference greater than 97th centile compared to appropriate, age matched, sex-matched normal standards. Alternatively, a apparently increased size of the cranium. Evidence: PCS. Frequency: 1/1. (PMID:16411219)
- Short ribs (HP:0000773): Reduced rib length. Evidence: PCS. Frequency: 1/1. (PMID:16411219)
- Premature rupture of membranes (HP:0001788): Premature rupture of membranes (PROM) is a condition which occurs in pregnancy when the amniotic sac ruptures more than an hour before the onset of labor. Evidence: PCS. Frequency: 1/1. (PMID:16411219)
- Brain stem compression (HP:0002512). Evidence: IEA. (OMIM:100800)
- Small foramen magnum (HP:0002677): An abnormal narrowing of the foramen magnum. Evidence: PCS. Frequency: 1/1. (PMID:16411219)
- Polyhydramnios (HP:0001561): The presence of excess amniotic fluid in the uterus during pregnancy. Evidence: PCS. Frequency: 1/1. (PMID:16411219)
- Choanal stenosis (HP:0000452): Abnormal narrowing of the choana (the posterior nasal aperture). Evidence: PCS. Frequency: 1/1. (PMID:16411219)
- Genu varum (HP:0002970): A positional abnormality marked by outward bowing of the legs in which the knees stay wide apart when a person stands with the feet and ankles together. Evidence: TAS. (OMIM:100800)
- Feeding difficulties (HP:0011968): Impaired ability to eat related to problems gathering food and getting ready to suck, chew, or swallow it. Evidence: PCS. Frequency: 1/1. (PMID:16411219)
- Respiratory distress (HP:0002098): Respiratory distress is objectively observable as the physical or emotional consequences from the experience of dyspnea. The physical presentation of respiratory distress is generally referred to as labored breathing, while the sensation of respiratory distress is called shortness of breath or dyspnea. Evidence: PCS. Frequency: 1/1. (PMID:16411219)
- Malar flattening (HP:0000272): Underdevelopment of the malar prominence of the jugal bone (zygomatic bone in mammals), appreciated in profile, frontal view, and/or by palpation. Evidence: IEA. (OMIM:100800)
- Craniocervical junction constriction (HP:6000920): Congenital or acquired abnormalities of the occipital bone, foramen magnum, or first two cervical vertebrae that decrease the space for the lower brain stem and cervical cord. These malformations can lead to cranial nerve compression, vertebral artery compression, and obstructive hydrocephalus. Evidence: PCS. (PMID:33103849)
- Midface retrusion (HP:0011800): Posterior positions and/or vertical shortening of the infraorbital and perialar regions, or increased concavity of the face and/or reduced nasolabial angle. Evidence: TAS. (OMIM:100800)
- Depressed nasal bridge (HP:0005280): Posterior positioning of the nasal root in relation to the overall facial profile for age. Evidence: PCS. Frequency: 1/1. (PMID:16411219)
- Recurrent otitis media (HP:0000403): Increased susceptibility to otitis media, as manifested by recurrent episodes of otitis media. Evidence: TAS. (OMIM:100800)
- Conductive hearing impairment (HP:0000405): An abnormality of vibrational conductance of sound to the inner ear leading to impairment of sensory perception of sound. Evidence: IEA. (OMIM:100800)
- Frontal bossing (HP:0002007): Bilateral bulging of the lateral frontal bone prominences with relative sparing of the midline. Evidence: PCS. Frequency: 1/1. (PMID:16411219)
- Neonatal short-limb short stature (HP:0008921): A type of short-limbed dwarfism that is manifest beginning in the neonatal period. Evidence: TAS. (OMIM:100800)
- Radial bowing (HP:0002986): A bending or abnormal curvature of the radius. Evidence: PCS. Frequency: 1/1. (PMID:16411219)
- Autosomal dominant inheritance (HP:0000006): 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 heterozygotes. In the context of medical genetics, an autosomal dominant disorder is caused when a single copy of the mutant allele is present. Males and females are affected equally, and can both transmit the disorder with a risk of 50% for each child of inheriting the mutant allele. Evidence: PCS. (PMID:16411219)
These phenotypes are associated with the disease achondroplasia (OMIM:100800).