Glossary
There are currently 40 names in this directory beginning with the letter S.
Saethre–Chotzen syndrome
"acrocephalosyndactyly" disorder characterized by anomalies of the craniofacial area and hands and feet including craniofacial asymmetry, widely spaced eyes (ocular hypertelorism) with unusually shallow eye cavities (orbits), drooping of the upper eyelids (ptosis), and strabismus; occasional "beaked" nose, deviated nasal septum, small, low-set ears; or underdeveloped upper jaw (hypoplastic maxilla), partial fusion of soft tissues (cutaneous syndactyly) of certain fingers and toes (digits); unusually short digits (brachydactyly); and broad great toes; caused by mutations in the TWIST1 gene located on the short arm (p) of chromosome 7 at 7p21; autosomal dominant inheritance
San Luis Valley Syndrome
recombinant 8 syndrome; characterized by heart and urinary tract abnormalities, moderate to severe intellectual disability, and a distinctive facial appearance and caused rearrangement of chromosome 8 that results in a deletion of a piece of the short (p) arm and a duplication of a piece of the long (q) arm
Sanger sequencing
method of DNA sequencing based on the selective incorporation of chain-terminating dideoxynucleotides by DNA polymerase during in vitro DNA replication
Schizophrenia
long-term mental disorder of a type involving a breakdown in the relation between thought, emotion, and behavior, leading to faulty perception, inappropriate actions and feelings, a sense of mental fragmentation, and withdrawal from reality and personal relationships into fantasy and delusion
Septum pellucidum
thin, triangular, vertical membrane separating the anterior horns of the left and right lateral ventricles of the brain
Sex chromosomes
chromosomes carrying the genes responsible for determining the sex of offspring, in humans the sex chromosomes are designated X and Y; females have 2 X chromosomes and males have one X and one Y chromosome
Single nucleotide polymorphism (SNP)
differences at the individual nucleotide level among individuals
Situs inversus
condition in which the heart and other organs of the body are transposed through the sagittal plane to lie on the opposite side from the usual
Smith–Magenis syndrome
complex developmental disorder characterized by distinctive facial features, skeletal malformations, varying degrees of intellectual impairment, speech and motor delays, sleep disturbances, and self-injurious or attention-seeking behaviors; caused by deletion of the RAI1 gene located on the short arm of chromosome 17 within the 17p11.2 region
Somatic mutation
change in the genetic structure that is neither inherited nor passed to offspring; can occur in any of the cells of the body except the germ cells (sperm and egg)
Sotos Syndrome
overgrowth disorder, characterized by excessive growth prenatally and postnatally, a large elongated head, distinctive facial configuration, and a non-progressive neurological disorder with intellectual disability; may show advanced bone age; caused by mutation in the NSD1 gene located on the long arm of chromosome 5 at 5q35.2-q35.3
Spherocytosis
disorder of the red blood cell membrane clinically characterized by anemia, jaundice (yellowing) and splenomegaly (enlargement of the spleen)
Spina bifida
major birth defect and a type of neural tube defect that involves an opening in the vertebral column caused by the failure of the neural tube to close properly during embryonic development
Stem cell
an undifferentiated cell that retains the ability to give rise to other, more specialized cells
Stop codon
Any of three codons, UAA, UAG, or UGA, that signal the termination of the synthesis of a protein
Strabismus
disorder of vision due to a deviation from normal orientation of one or both eyes so that both cannot be directed at the same object at the same time; squint; crossed eyes
Supravalvular aortic stenosis
fixed form of congenital left ventricular outflow tract (LVOT) obstruction that occurs as a localized or diffuse narrowing of the ascending aorta beyond the superior margin of the sinuses of Valsalva
Syndactyly
condition in which fingers or toes are joined together; can involve the bones or just the skin
Syndactyly, cutaneous fingers
soft tissue continuity in the A/P axis between two fingers that extends distally to at least the level of the proximal interphalangeal joints
Syndactyly, cutaneous toes
soft tissue continuity in the A/P axis between adjacent foot digits that involves at least half of the P/D length of one of the two involved digits
Syndrome
group of three or more characteristics and/or symptoms that occur together in a recognizable pattern and cause a particular disease state or condition