- Skeletal muscle atrophy (HP:0003202): The presence of skeletal muscular atrophy (which is also known as amyotrophy). Evidence: IEA. (OMIM:300559)
- 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: 2/2. (PMID:15637709;OMIM:300559)
- Quadriceps muscle weakness (HP:0003731): Weakness of the quadriceps muscle (that is, of the muscle fasciculus of quadriceps femoris). Evidence: PCS. Frequency: 1/1. (PMID:15637709)
- Reduced muscle phosphorylase kinase activity (HP:6000198): Activity of the enzyme muscle phosphorylase kinase (PhK) in muscle tissue below the lower limit of normal. Evidence: PCS. Frequency: 1/1. (PMID:15637709)
- Middle age onset (HP:0003596): A type of adult onset with onset of symptoms at the age of 40 to 60 years. Evidence: PCS. Frequency: 3/3. (PMID:7874115;PMID:15637709)
- Distal amyotrophy (HP:0003693): Muscular atrophy affecting muscles in the distal portions of the extremities. Evidence: PCS. Frequency: 1/1. (PMID:7874115)
- Glycogen accumulation in muscle fiber lysosomes (HP:0030231): An increased amount of glycogen in muscle tissue found specifically in lysosomes. Evidence: PCS. Frequency: 1/1. (PMID:7874115)
- Distal muscle weakness (HP:0002460): Reduced strength of the musculature of the distal extremities. Evidence: PCS. Frequency: 1/1. (PMID:7874115)
- Reduced tissue phosphorylase kinase activity (HP:6000832): Concentration or activity of phosphorylase kinase below the lower limit of normal. This enzyme can be measured in multiple tissues including leukocytes and cultured fibroblasts. Evidence: TAS. (OMIM:300559)
- Increased muscle glycogen content (HP:0009051): An increased amount of glycogen in muscle tissue. Evidence: PCS. Frequency: 1/1. (PMID:15637709)
- 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:7874115)
- Lower limb muscle weakness (HP:0007340): Weakness of the muscles of the legs. Evidence: PCS. Frequency: 1/1. (PMID:7874115)
- Exercise-induced myalgia (HP:0003738): The occurrence of an unusually high amount of muscle pain following exercise. Evidence: IEA. (OMIM:300559)
- Pelvic girdle muscle weakness (HP:0003749): Weakness of the muscles of the pelvic girdle (also known as the hip girdle), that is, lack of strength of the muscles around the pelvis. Evidence: PCS. Frequency: 1/1. (PMID:15637709)
- Hypoglycemia (HP:0001943): A decreased concentration of glucose in the blood. Evidence: PCS. Frequency: 1/1. (PMID:7874115)
- Muscle weakness (HP:0001324): Reduced strength of muscles. Evidence: IEA. (OMIM:300559)
- Exercise-induced myoglobinuria (HP:0008305): Presence of myoglobin in the urine following exercise. Evidence: IEA. (OMIM:300559)
- Muscle fiber necrosis (HP:0003713): Abnormal cell death involving muscle fibers usually associated with break in, or absence of, muscle surface fiber membrane and resulting in irreversible damage to muscle fibers. Evidence: PCS. Frequency: 1/1. (PMID:7874115)
- Exercise-induced muscle stiffness (HP:0008967): A type of muscle stiffness that occurs following physical exertion. Evidence: IEA. (OMIM:300559)
- Exercise intolerance (HP:0003546): A functional motor deficit where individuals whose responses to the challenges of exercise fail to achieve levels considered normal for their age and gender. Evidence: IEA. Frequency: 1/1. (OMIM:300559)
These phenotypes are associated with the disease glycogen storage disease IXd (OMIM:300559).