- Type 1 muscle fiber atrophy (HP:0011807): Atrophy (wasting) affecting primary type 1 muscle fibers. This feature in general can only be observed on muscle biopsy. Evidence: TAS. (OMIM:310300)
- Skeletal muscle atrophy (HP:0003202): The presence of skeletal muscular atrophy (which is also known as amyotrophy). Evidence: PCS. Frequency: 1/1. (PMID:29250285)
- Achilles tendon contracture (HP:0001771): A contracture of the Achilles tendon. Evidence: PCS. Frequency: 1/1. (PMID:29250285)
- Juvenile onset (HP:0003621): Onset of signs or symptoms of disease between the age of 5 and 15 years. Evidence: PCS. Frequency: 11/11. (PMID:29250285;OMIM:310300)
- Elevated circulating creatine kinase activity (HP:0003236): The activity of creatine kinase in the blood circulation is above the upper limit of normal. Evidence: PCS. Frequency: 1/1. (PMID:29250285)
- Decreased cervical spine flexion due to contractures of posterior cervical muscles (HP:0004631). Evidence: IEA. (OMIM:310300)
- Abnormality of the neck (HP:0000464): An abnormality of the neck. Evidence: IEA. (OMIM:310300)
- Myopathy (HP:0003198): A disorder of muscle unrelated to impairment of innervation or neuromuscular junction. Evidence: IEA. (OMIM:310300)
- First degree atrioventricular block (HP:0011705): Delay of conduction through the atrioventricular node, which is manifested as prolongation of the PR interval in the electrocardiogram (EKG). All atrial impulses reach the ventricles. Evidence: PCS. Frequency: 1/1. (PMID:29250285)
- Atrial arrhythmia (HP:0001692): A type of supraventricular tachycardia in which the atria are the principal site of electrophysiologic disturbance. Evidence: IEA. (OMIM:310300)
- Knee flexion contracture (HP:0006380): A type of knee joint contracture in which the knee is in a fixed bent (flexed) configuration such that it cannot be straightened actively or passively. Evidence: PCS. Frequency: 1/1. (PMID:29250285)
- 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: IEA. (OMIM:310300)
- Childhood onset (HP:0011463): Onset of disease at the age of between 1 and 5 years. Evidence: TAS. (OMIM:310300)
- Absent P wave (HP:0033122): The P wave that normally precedes each QRS complex by a fixed PR interval of 120 to 200 milliseconds is not present. Evidence: PCS. Frequency: 1/1. (PMID:29250285)
- 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. (OMIM:310300)
- Waddling gait (HP:0002515): Weakness of the hip girdle and upper thigh muscles, for instance in myopathies, leads to an instability of the pelvis on standing and walking. If the muscles extending the hip joint are affected, the posture in that joint becomes flexed and lumbar lordosis increases. The patients usually have difficulties standing up from a sitting position. Due to weakness in the gluteus medius muscle, the hip on the side of the swinging leg drops with each step (referred to as Trendelenburg sign). The gait appears waddling. The patients frequently attempt to counteract the dropping of the hip on the swinging side by bending the trunk towards the side which is in the stance phase (in the German language literature this is referred to as Duchenne sign). Similar gait patterns can be caused by orthopedic conditions when the origin and the insertion site of the gluteus medius muscle are closer to each other than normal, for instance due to a posttraumatic elevation of the trochanter or pseudarthrosis of the femoral neck. Evidence: IEA. (OMIM:310300)
- Loss of ambulation (HP:0002505): Inability to walk in a person who previous had the ability to walk. Evidence: PCS. Frequency: 1/1. (PMID:29250285)
- Palpitations (HP:0001962): A sensation that the heart is pounding or racing, which is a non-specific sign but may be a manifestation of arrhythmia. Evidence: PCS. Frequency: 1/1. (PMID:29250285)
- Elbow flexion contracture (HP:0002987): An elbow contracture that limits the ability of the elbow joint to be extended (straightened), meaning that the elbow is fixed in an flexed (bent) position. Evidence: PCS. Frequency: 1/1. (PMID:29250285)
- Sudden cardiac death (HP:0001645): The heart suddenly and unexpectedly stops beating resulting in death within a short time period (generally within 1 h of symptom onset). Evidence: TAS. (OMIM:310300)
- Slowly progressive (HP:0003677): Applies to a disease manifestation that only slowly increases in scope or severity over the course of time. Evidence: PCS. (PMID:29250285)
- Atrioventricular block (HP:0001678): Delayed or lack of conduction of atrial depolarizations through the atrioventricular node to the ventricles. Evidence: IEA. (OMIM:310300)
These phenotypes are associated with the disease Emery-Dreifuss muscular dystrophy 1, X-linked (OMIM:310300).