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  • Malrotation: Abnormal rotation of all or part of an organ, such as the small intestines.
  • Microtubule: A rod-like structure that in a normal cilium exists as an array of 9 doublets arranged in an outer circle around a central pair.
  • Middle Ear: A narrow air-filled space between the tympanic membrane (ear drum) and inner ear which contains the three small bones that conduct sounds.
  • Missense Mutation: A change in one DNA base pair that changes a codon into a codon corresponding to a different amino acid.
  • Molecular Genetic Testing: (synonyms - DNA testing, DNA-based testing, molecular testing) Testing that involves the analysis of DNA, either through linkage analysis, sequencing, or one of several methods of mutation detection.
  • Mucociliary Clearance: The primary defense mechanism of the lungs in which tiny, hairlike structures called cilia that line the airways beat in waves to clear mucus-containing particles or pathogens trapped within it out of the airways. This protective mechanism keeps the lungs in an almost sterile environment, combatting the constant exposure of the lungs to potentially harmful particles, gases, and viral, bacterial, and fungal pathogens.
  • Mutation: (synonyms - sequence alteration, splicing mutation) Any alteration in a gene from its natural state; may be disease-causing or a benign, normal variant.
  • Mutation Analysis: (synonym - targeted mutation analysis) Testing for the presence of a specific mutation (e.g., Glu6Val for sickle cell anemia), a specific type of mutation (e.g., the trinucleotide repeat expansion associated with spinocerebellar ataxia type 1, deletions associated with Duchenne muscular dystrophy), or set of mutations (e.g., a panel of mutations for cystic fibrosis), as opposed to complete gene sequencing or mutation scanning, which detect most mutations in the tested region.
  • Mutation Screening (Mutational Profiling): A process by which a segment of DNA is screened via one of a variety of methods to identify variant gene region(s). Variant regions are further analyzed (by sequence analysis or mutation analysis) to identify the sequence alteration.