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.

Benign — not causing harm. Noncancerous in the context of tumors.

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 prenatal and can be used as an early detection of TSC.

Cell proliferation — an increase in the number of cells due to cell division and growth.

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.

DNA — deoxyribonucleic acid. The molecules inside cells that carry genetic information and pass it from one generation to the next.

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.

Gene — pieces of information containing instructions for making proteins. Genes are the basic hereditary unit that is passed from a parent to child.

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 are best seen with a Wood’s lamp.

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

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

Inherited — passed on from parent to offspring.

Lymphangioleiomyomatosis (LAM) — pulmonary involvement is rare, seen exclusively in woman 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.

Macrocephaly — abnormally large head circumference.

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

Malignant — causing harm. Cancerous in the context of tumors.

Mutation — a permanent change in DNA.

Neurocognitive — relating to thinking processes.

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

Protein — a class of molecules found in all living cells. Proteins are required for the structure, function and regulation of the body’s cells, tissues and organs.

PTEN gene — Phosphatase and Tensin Homolog (PTEN) is a tumor suppressor gene that provides instruction for making a protein found in almost all tissue in the body. When functioning properly, the PTEN protein helps regulate cell division and proliferation by keeping cells from growing in an uncontrolled way.

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

Retinal nodula hamartomas — elevated mulberry or plaque-like lesions in the retina. Retinal involvement usually remains dormant.

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 that have grown and if left untreated, can cause hydrocephalus.

Subependymal nodules (SENs) — benign 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.

Tumor — an abnormal mass of tissue resulting from uncontrolled cell growth. Tumors can be benign (non-cancerous) or malignant (cancerous).

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.