22q13.3 deletion syndrome — another name for Phelan McDermid Syndrome. PMS occurs due to a loss of a region labeled q13.3 on chromosome 22.

Angiomyolipomas (AMLS) — tumor-like lesions composed of blood vessels, smooth muscle, and adipose tissue that occur in the kidneys of adult patients.

Café-au-lait spots — birthmark on skin that is coffee colored.

Cardiac rhabdomyomas — benign heart tumors that are found in up to two-thirds of patients with TSC. Cardiac rhabdomyomas may develop prenatally and can be used as an early detection of TSC.

Chromosome — composed of DNA molecules (genes) that help make up organisms

Chromosomal microarray analysis — a type of genetic testing that looks for duplicate of deleted chromosomal pieces.

Cortical tubers — collection of abnormally sized neurons and their supporting cells.

De novo — a gene change that is present for the first time in a family member due to a genetic mutation in one of the reproductive cells of a parent or in the fertilized egg.

Facial angiofibromas — characteristic skin lesions that typically occur over the nose, check and chin. Can appear as flesh-colored or red papules.

Forehead plaque — raised, discolored and sometimes hard areas on the forehead.

Harmartomas — benign masses of abnormally developed tissue.

Hydrocephalus — swelling of the brain that requires immediate neurosurgical intervention causes by a blockage in cerebrospinal fluid circulation throughout the ventricles of the brain.

Hypomelanotic macule — white skin patches that occur all over the body and may be more easily detected with a Wood’s lamp.

Hypotonia — low muscle tone that is associated with reduced strength.

Infantile spasms — a type of epilepsy that occurs in about one-third of patients with TSC. The peak onset is at 4-6 months and are characterized by brief but often repetitive, muscle contraction involving the head, trunk and extremities.

Lymphangioleiomyomatosis (LAM) — pulmonary involvement is rare, seen exclusively in women around the age of 30. Seen as an overgrowth of abnormal muscle-like cells in the lungs and can result in difficulty breathing, chest pain, and coughing.

Magnetic resonance imaging (MRI) — noninvasive imaging used to see different features of the body and brain.

Mutation — a permanent change in DNA.

Neurocognitive — a descriptive term for brain functions relating to thinking processes.

Periungual fibroma — a benign tumor that occurs on the fingernail or toenail.

Retinal achromatic patch — hypopigmented patch in the back of the retina.

Retinal hamartomas — elevated mulberry or plaque-like lesions in the retina.

Shagreen patch — flesh colored and dimpled, resembling an orange peel, skin patch found on the lower back.

SHANK3 gene — a gene that encodes for a master scaffolding protein involved in synaptic functioning.

Subependymal giant cell astrocytomas (SEGAs) — tumor-like lesions in the brain that have grown and if left untreated, can cause hydrocephalus.

Subependymal nodules (SENs) — benign, non-growing lesions found along the wall of the lateral ventricles in the brain.

TSC1 gene — The tuberous sclerosis 1 gene is a tumor suppressor gene that produces a product called hamartin, which interacts with tuberin (the product of the TSC2 gene). This forms a complex and plays a role in cell growth and division.

TSC2 gene — The tuberous sclerosis 2 gene produces the protein tuberin, which interacts with hamartin (the product of the TSC1 gene) and is thought to function as a tumor suppressor gene.

Ungual fibroma — a benign tumor that occurs on the fingernail or toenail.

Wood’s lamp — lamp used to detect various skin conditions through ultraviolet radiation.