The presence of an unusually high plantar arch. Also called high instep, pes cavus refers to a distinctly hollow form of the sole of the foot when it is bearing weight.

Hyperextension of the metatarsal-phalangeal joint with hyperflexion of the proximal interphalangeal (PIP) joint.

Hypertrophic cardiomyopathy (HCM) is defined by the presence of increased ventricular wall thickness or mass in the absence of loading conditions (hypertension, valve disease) sufficient to cause the observed abnormality.

The presence of an abnormality of cardiac function that is responsible for the failure of the heart to pump blood at a rate that is commensurate with the needs of the tissues or a state in which abnormally elevated filling pressures are required for the heart to do so. Heart failure is frequently related to a defect in myocardial contraction.

Hypertrophic cardiomyopathy with an symmetrical and concentric pattern of hypertrophy.

Any abnormality of the cardiovascular system.

Abnormal rhythm of the heart.

A type of subvalvular aortic stenosis resulting from thickening of the musculature of the interventricular septum, which results in obstruction to blood flow through the left-ventricular outflow tract.

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).

Dysarthric speech is a general description referring to a neurological speech disorder characterized by poor articulation. Depending on the involved neurological structures, dysarthria may be further classified as spastic, flaccid, ataxic, hyperkinetic and hypokinetic, or mixed.

Upturning of the big toe (and sometimes fanning of the other toes) in response to stimulation of the sole of the foot. If the Babinski sign is present it can indicate damage to the corticospinal tract.

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.

Diminution of tendon reflexes, which is an invariable sign of peripheral nerve disease.

An abnormality of the medulla oblongata, the lower half of the brainstem.

Any structural abnormality of the pyramidal tract, whose chief element, the corticospinal tract, is the only direct connection between the brain and the spinal cord. In addition to the corticospinal tract, the pyramidal system includes the corticobulbar, corticomesencephalic, and corticopontine tracts.

An abnormality of the dorsal columns, i.e., of the dorsal portion of the gray substance of the spinal cord. The dorsal column consists of the fasciculus gracilis and fasciculus cuneatus and itself is part of the dorsal funiculus.

A reduction in the amplitude of sensory nerve action potential. This feature is measured by nerve conduction studies.

An abnormality of the spinocerebellar tracts, a set of axonal fibers originating in the spinal cord and terminating in the ipsilateral cerebellum. The spinocerebellar tract convey information to the cerebellum about limb and joint position (proprioception). They comprise the ventral spinocerebellar tract, the anterior spinocerebellar tract, and the posterior spinocerebellar tract.

The presence of an abnormal lateral curvature of the spine.

A type of diabetic metabolic abnormality with an accumulation of ketone bodies.

A decreased rate of pyruvate carboxylase activity.

Rhythmic, involuntary oscillations of one or both eyes related to abnormality in fixation, conjugate gaze, or vestibular mechanisms.

Structural abnormalities that impede fluid drainage in the eye increase ocular pressure. These abnormalities may be present at birth and usually become apparent during the first year of life. Such structural abnormalities may be part of a genetic disorder that affects many body systems, called a syndrome. If glaucoma appears before the age of 3 without other associated abnormalities, it is called primary congenital glaucoma.\n\nUsually glaucoma develops in older adults, in whom the risk of developing the disorder may be affected by a variety of medical conditions including high blood pressure (hypertension) and diabetes mellitus, as well as family history. The risk of early-onset glaucoma depends mainly on heredity.\n\nIn most people with glaucoma, the damage to the optic nerves is caused by increased pressure within the eyes (intraocular pressure). Intraocular pressure depends on a balance between fluid entering and leaving the eyes.\n\nOther individuals experience early onset of primary open-angle glaucoma, the most common adult form of glaucoma. If primary open-angle glaucoma develops during childhood or early adulthood, it is called juvenile open-angle glaucoma.\n\nGlaucoma is a group of eye disorders in which the optic nerves connecting the eyes and the brain are progressively damaged. This damage can lead to reduction in side (peripheral) vision and eventual blindness. Other signs and symptoms may include bulging eyes, excessive tearing, and abnormal sensitivity to light (photophobia). The term "early-onset glaucoma" may be used when the disorder appears before the age of 40.