Phenotypes associated with the disease posterior column ataxia (OMIM:176250, an entry in Online Mendelian Inheritance in Man):
- Scoliosis (HP:0002650, a Human Phenotype Ontology term): The presence of an abnormal lateral curvature of the spine. Evidence: TAS. (OMIM:176250)
- Impaired vibratory sensation (HP:0002495, a Human Phenotype Ontology term): A decrease in the ability to perceive vibration. Clinically, this is usually tested with a tuning fork which vibrates at 128 Hz and is applied to bony prominences such as the malleoli at the ankles or the metacarpal-phalangeal joints. There is a slow decay of vibration from the tuning fork. The degree of vibratory sense loss can be crudely estimated by counting the number of seconds that the examiner can perceive the vibration longer than the patient. Evidence: TAS. (OMIM:176250)
- Ataxia (HP:0001251, a Human Phenotype Ontology term): 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. (OMIM:176250)
- Autosomal dominant inheritance (HP:0000006, a Human Phenotype Ontology term): 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: TAS. (OMIM:176250)
- Diminished deep tendon reflex (HP:0001315, a Human Phenotype Ontology term): A reduction (hyporeflexia) or complete absence (areflexia) of the involuntary muscle contraction normally elicited by a reflex stimulus, such as tapping a deep tendon. Evidence: TAS. (OMIM:176250)
- Impaired proprioception (HP:0010831, a Human Phenotype Ontology term): A loss or impairment of the sensation of the relative position of parts of the body and joint position. Evidence: TAS. (OMIM:176250)