hypoglycemia (Low blood sugar), vomiting, lethargy, encephalopathy (brain disease), respiratory arrest, hepatomegaly (enlarged liver), seizures, apnea, cardiac arrest, coma, and sudden death. Long-term outcomes may include developmental and behavioral disability, chronic muscle weakness, failure to thrive, cerebral palsy, and attention deficit hyperactivity disorder (ADHD).
A precipitating factor is needed for clinical symptoms to present. It is often in times of metabolic stress induced by fasting or infection, when the demands on fatty acid oxidation are particularly high, that an MCAD-deficient patient may present with symptoms. Factors that may contribute to presentation and/or increased severity of clinical outcomes include prolonged fasting, infections or recent immunization, age, and family history of Sudden Infant Death Syndrome (SIDS) or MCAD deficiency.
MCAD mutations can be identified through DNA-based tests using polymerase chain reaction (PCR) and therefore can be detected in newborns by DNA analysis from newborn blood spots. Mass screening for MCAD deficiency, however, is generally conducted with the detection of abnormal metabolites in urine or blood by tandem mass spectrometry . Typically, this technique is used as an initial screening modality followed by confirmation of MCAD deficiency with urine organic acid profile or DNA mutation analysis. Testing for MCAD deficiency can be done as one of the battery of newborn screening tests.
- McArdle disease
Glycogen storage disease type V and the most common type of glycogen storage disease. McArdle disease is an autosomal recessive disorder caused by mutations in the gene that encodes myophosphorylase, an enzyme that is essential for glycogenolysis. Exercise intolerance usually develops during childhood, along with pain, cramps, and fatigue in exercised muscle. These symptoms are […]
The Medical College Admissions Test, a test that is required of all applicants to medical school in the U.S. and Canada. The MCAT is “a standardized test used to assess applicants’ science knowledge, reasoning, and communication and writing skills.” The MCAT is administered by the Association of American Medical Colleges.
- McBurney's point
McBurney’s point is the most tender area of the abdomen of patients in the early stage of appendicitis. McBurney’s point is named after the 19th-century New York surgeon Charles McBurney (1845-1913) who was the leading authority in his day on the diagnosis and treatment of appendicitis. Dr. McBurney in 1889 showed that incipient appendicitis could […]
- McClintock, Barbara
(1902-1992) American geneticist who won the 1983 Nobel Prize in Physiology or Medicine for her discovery of genetic transposition, or the ability of genes to change position on the chromosome. Barbara McClintock was born in Hartford, Connecticut. Her family moved to Brooklyn, New York, in 1908. McClintock earned her B.S. and M.S. degrees in botany […]
- McCune-Albright syndrome
A genetic disorder of bones, skin pigmentation and hormonal problems with premature sexual development. Also called Albright syndrome or polyostotic fibrous dysplasia. In the syndrome, there is bone disease with fractures and deformity of the legs, arms and skull; pigment patches of the skin; and endocrine (hormonal) disease with early puberty (early menstrual bleeding, development […]