Genetic and Medical Glossary


All | # A B C D E F G H I J K L M N O P Q R S T U V W X Y Z
There are currently 27 names in this directory beginning with the letter N.
Nail, bifid
digit with two nails, with at least some soft tissue between them

Nares, anteverted
anteriorly-facing nostrils viewed with the head in the Frankfurt horizontal and the eyes of the observer level with the eyes of the subject; tip of the nose is upturned and is positioned superiorly to the nasal base, allowing the nares to be easily visualized from the front

Naris, single
one external opening of the nose; may occur in the midline or on one side and be symmetrical or asymmetrical

Naris, supernumerary
more than two nares

Nasal bridge, depressed
posterior positioning of the nasal root in relation to the overall facial profile for age

Nasal bridge, wide
increased breadth of the nasal bridge

Nasal cartilage, absent
lack of a palpable nasal cartilage; there may also be deficiency of the nasal bone, often related to holoprosencephaly

Nasal tip, overhanging
positioning of the nasal tip inferior to the nasal base

Neck webbing
paravertically oriented fold of skin on the postero-lateral aspect of the neck, usually extending from the mastoid region of the skull to the acromion, most noticeable in frontal or posterior view

clusters of microscopic blastema cells, tubules, and stromal cells at the periphery of the renal lobes in an infant; believed to be a precursor of Wilmsā€™ tumor

Neural tube
the embryonic precursor to the spinal cord and brain, which normally closes at small openings, or neuropores, by the twenty-eighth day of gestation in humans

childhood form of cancer that arises in the adrenal gland or in tissue in the nervous system that is related to the adrenal gland

Neurofibromatosis I (NF1)
genetic disorder characterized by the development of multiple noncancerous (benign) tumors of nerves and skin (neurofibromas) and areas of abnormally decreased or increased coloration (hypo- or hyperpigmentation) of the skin; areas of abnormal pigmentation typically include pale tan or light brown discolorations (cafe-au-lait spots) on the skin of the trunk and other regions as well as freckling, particularly under the arms and in the groin; caused by mutations of gene on the long arm (q) of chromosome 17 at 17q11.2

Neurofibromatosis type II
characterized by benign (noncancerous) tumors of the nerves that transmit sound impulses from the inner ears to the brain; associated symptoms may include disturbances of balance and walking (gait), dizziness, headache, facial weakness or numbness, ringing in the ears (tinnitus), and/or progressive hearing loss; caused by mutations of a gene on the long arm (q) of chromosome 22 at 22q12.2

Noncoding DNA
a strand of DNA that is unable to make protein because it lacks the necessary information

the improper division of chromosomes during anaphase of mitosis or meiosis, resulting in cells with abnormal numbers of chromosomes and sometimes seriously altered phenotypes

Nonhistone proteins
a heterogeneous group of acidic or neutral proteins found in chromatin that may be involved with chromosome structure, chromatin packaging, or the control of gene expression

Nonsense codon
another term for a termination or stop codon (UAA, UAG, or UGA)

Nonsense mutation
a DNA mutation that changes an existing amino acid codon in a message to one of the three termination, or stop, codons; this results in an abnormally short or truncated protein that is usually nonfunctional

Nose, absent
complete absence of all nasal structures

Nose, bifid
visually assessable vertical indentation, cleft, or depression of the nasal bridge, ridge and tip

Nuchal skin, Redundant
excess skin around the neck, often lying in horizontal folds

Nucleic acid
the genetic material of cells, found in two forms: deoxyribonucleic acid (DNA) and ribonucleic acid (RNA); composed of repeating subunits called nucleotides

a building block of nucleic acids, composed of a sugar (deoxyribose or ribose) and one of the nitrogenous bases: adenine (A), cytosine (C), guanine (G), thymine (T), or uracil (U)

a building block of nucleic acids, composed of a sugar (deoxyribose or ribose), one of the nitrogenous bases (adenine, cytosine, guanine, thymine, or uracil) and one or more phosphate groups

having two less than the diploid number of chromosomes due to loss of one chromosome pair

Rapid, rhythmic, repetitious, and involuntary eye movements

You are donating to : Chromosome Disorder Outreach, Inc, a 501(c)(3) non-profit organization.

How much would you like to donate?
$25 $50 $100
Would you like to make regular donations? I would like to make donation(s)
How many times would you like this to recur? (including this payment) *
Name *
Last Name *
Email *
Additional Note