Enlargement or increased size of the heart left ventricle.

Failure to thrive (FTT) refers to a child whose physical growth is substantially below the norm.

Impaired ability to eat related to problems gathering food and getting ready to suck, chew, or swallow it.

Reduced ability of the liver to perform its functions.

An inadequate sucking reflex, resulting in the difficult of newborns to be breast-fed.

A condition in which the stomach contents leak backwards from the stomach into the esophagus through the lower esophageal sphincter.

A type of hearing impairment in one or both ears related to an abnormal functionality of the cochlear nerve.

Failure to record otoacoustic emissions (OAE), i.e., sounds generated from the cochlea in response to an acoustic stimulus and transmitted across the middle ear to the external ear canal.

Polymicrogyria is a congenital malformation of the cerebral cortex characterized by abnormal cortical layering (lamination) and an excessive number of small gyri (folds).

Increased concentration of lactate in the cerebrospinal fluid.

A type of polymicrogyria with a gradient of severity (anterior more severe than posterior) extending from frontal poles posteriorly to precentral gyrus and inferiorly to frontal operculum.

Hypotonia is an abnormally low muscle tone (the amount of tension or resistance to movement in a muscle). Even when relaxed, muscles have a continuous and passive partial contraction which provides some resistance to passive stretching. Hypotonia thus manifests as diminished resistance to passive stretching. Hypotonia is not the same as muscle weakness, although the two conditions can co-exist.

An abnormal appearance of muscle fibers observed on muscle biopsy. Ragged red fibers can be visualized with Gomori trichrome staining as irregular and intensely red subsarcolemmal zones, whereas the normal myofibrils are green. The margins of affect fibers appear red and ragged. The ragged-red is due to the accumulation of abnormal mitochondria below the plasma membrane of the muscle fiber, leading to the appearance of a red rim and speckled sarcoplasm.

An abnormally reduced activity of the enzyme cytochrome C oxidase in muscle tissue.

A severe form of respiratory insufficiency characterized by inadequate gas exchange such that the levels of oxygen or carbon dioxide cannot be maintained within normal limits.

An abnormal buildup of lactic acid in the body, leading to acidification of the blood and other bodily fluids.

The concentration of aspartate aminotransferase (AST) in the blood circulation is above the upper limit of normal.

An abnormally high concentration in the circulation of alanine aminotransferase (ALT).

An increased concentration of alanine in the blood.

Abnormally increased level of blood lactate (2-hydroxypropanoic acid). Lactate is produced from pyruvate by lactate dehydrogenase during normal metabolism. The terms lactate and lactic acid are often used interchangeably but lactate (the component measured in blood) is strictly a weak base whereas lactic acid is the corresponding acid. Lactic acidosis is often used clinically to describe elevated lactate but should be reserved for cases where there is a corresponding acidosis (pH below 7.35).

Increased level of the enzyme gamma-glutamyltransferase (GGT). GGT is mainly present in kidney, liver, and pancreatic cells, but small amounts are present in other tissues.

An abnormal increase in the molar ratio of lactate to pyruvate in the blood circulation.

A reduction in the activity of the mitochondrial respiratory chain complex I, which is part of the electron transport chain in mitochondria.

A reduction in the activity of the mitochondrial respiratory chain complex III, which is part of the electron transport chain in mitochondria.

A reduction in the activity of the mitochondrial respiratory chain complex IV, which is part of the electron transport chain in mitochondria.

A reduction in the activity of the mitochondrial respiratory chain complex II, which is part of the electron transport chain in mitochondria.