Glossary of terms associated with Lissencephaly

Having struggled to understand detailed clinical and genetic papers on Lissencephaly I thought a glossary of specific terms would help make things a little clearer.

A
	a-	not, absent - like agenesis
	absence seizure	transitory interruption of conciousness without convusion (petit mal)
	agenesis of the corpus callosum	the corpus callosum failed to develop during pregnancy
	agyria	absence of gyri giving a smooth surface to part or all of the brain
	allele	a gene found in the same location on a pair of homologous chromosomes
	anoxia	no oxygen
	apnea	a temporary cessation of breathing
	ataxia	inability to coordinate voluntary muscle movements; unsteady movements and staggering gait
	atonic drop attack	seizure which involves a sudden loss of muscle control
	autosomal	an inheritance pattern indicating that the gene involved is not on one of the sex chromosomes. It is the opposite of sex-linked, or X-linked, or Y-linked.
	aversive seizure	seizure in which the head, eyes, or trunk turn to one side
B
	Bard button	plastic device fitted into the tummy -form of G-tube
	bi-temporal hollowing	a narrowing of the head at the temples
	brachycephaly	having a comparatively short head
	bradycardia	slow heartbeat
	brain stem	a part of the brain located at the top of the spinal chord that performs many of the low level brain functions (e.g. breathing)
C
	calcification	the hardening of a tissue by a deposit of calcium salts
	cavum septum pellucidum	the membranous partition that separates the frontal horns of the ventricles
	cerebellar vermis	1. either of two parts of the median lobe of the cerebellum: a) one slightly prominent on the upper surface -- also called superior vermis b) one on the lower surface sunk in the vallecula -- also called inferior vermis 2. the median lobe or part of the cerebellum
	cerebrum	the main bulk of the brain, formed by the cortex and white matter
	cerebellum	a small part of the brain located behind and below the cerebrum
	chromosome	each of the individual structures of DNA and protein found in the nuclei of cells that carry the genetic information in the form of genes. A chromosome generally has two arms known as the 'p' and 'q' arm.
	cisterna magna	a space containing fluid between the cerebellum and medulla oblongata
	Classical Lissencephaly	an umbrella term which encompasses MDS, ILS, SBH and Baraitser-Winter syndrome
	clinodactyly	a deformity of the hand marked by deviation or deflection of the fingers.
	colpocephaly	enlargement of the posterior horns of the ventricles
	complex partial seizure	loss of consciousness but may still allow the person to perform simple tasks
	contrast (in MRI or CT)	"with contrast" means that a substance was injected into a vein so that it fills the blood vessels of the brain so that they are visible in the scan.
	clonus	repeated quick spasms
	cortex	the outer part of the brain which normally consists of 6 layers of nerve cell bodies
	cortical visual impairment (CVI)	a condition where the brain is unable to accurately interpret what it sees. The actual eyes generally function OK with this condition.
	corpus callosum	part of the brain that joins the two hemispheres together
	CT (scan)	Computerised Tomography - the use of X rays and computers to produce an image of an organ
	cryptorchidism	the testicles fail to descend before the child is born
	cytomegalovirus (CMV)	CMV is a member of the herpes group of viruses, usually spread through close person to person contact. Can cause neurological development problems if contracted during pregnancy.
D
	DCX	the name of the X-linked gene associated with Lissencephaly and Subcortical Band Heterotopia. Located on the X chromosome at Xq22.3-q23. Also known as XLIS.
	de novo	a new occurrence (applied to a new genetic mutation)
	deletion	a missing part of a chromosome or gene
	dominant (autosomal -)	(and it's opposite recessive) - inheritance pattern indicating that only one mutant copy of the gene is required to get the disease.
	dys-	abnormal, wrong
	dysarthria	difficulty of speech or articulation
	dysfunction	abnormal functioning
	dysgenesis	created incorrectly
	dysmorphic	an anatomical malformation unusual features of the face or other organ or structure.
	dysphagia	difficulty in swallowing
	dysplasia	a formation of abnormal tissue (structurally wrong)
E
	-ectomy	cut out, remove
	EMX2	gene that is implicated in some cases of Schizencephaly.
	encephalocoele	hernia of the brain that is either congenital or due to trauma.
	epicanthal fold	a fold of skin around the eye. Epicanthus tarsalis is where the fold is most prominent in the upper eyelid. Epicanthus inversus is if the fold is most prominent in the lower eyelid. Epicanthus palpebralis is distributed equally in the upper and lower eyelid, and epicanthus supraciliaris is if the fold arises from the eyebrow extending to the lacrimal sac.
F
	facial diplegia	symmetrical paralysis of the same muscles on both sides of the face
	FCMD	gene that is implicated in Fukyama Muscular Dystrophy located at 9q31
	FISH	Fluorescence In Situ Hybridisation - a laboratory test for detecting genetic faults in chromosomes
	FLNA/FLN1/Filamin	gene that is implicated in Bilateral Periventricular Nodular Heterotopia (BPNH) located at Xq28
	focal seizure	motor seizure which begins in one part of the brain (and hence body) and then spreads to other muscle groups. There is no loss of conciousness.
	frontal lobe	the front part of the cerebrum
G
	G-tube	a feeding tube that goes straight into the stomach (G=gastric)
	genotype	the genetic constitution of an individual.
	glia	this is an old word that means "glue". Scientists used to think that glial cells were the glue that held the neurons in place in the brain, but now we know that they do lots of things. They make myelin. Other types of glia act to remove potassium ions from the spaces just outside neurons in the brain. (Neurons release potassium each time the generate an electrical signal.) One prominent theory of epilepsy is that the glia don't remove potassium well enough and its accumulation outside neurons causes them to fire out of control electrical signals, causing a seizure.
	gliosis	a proliferation of glial cells around a site of injury to the brain.
	grade 1,2,3,4,5,6	a classification system for ILS/MDS which grades the smoothness of the brain
	grey matter	where nerve cell bodies are located and where most information-processing occurs. It looks pinkish grey because of all the small blood vessels there
	gyri	the folds or convolutions normally seen on the surface of the brain
H
	haploinsufficiency	mutation in the heterozygous state which result in half normal levels of the gene product
	hemisphere	the two main parts of the cerebrum
	heterotopia	occurring in an abnormal place
	heterozygote	an individual who posses two different alleles in the the same chromosome pair
	homology	having the same structural features and pattern of genes
	hydrocephalus	large head circumference caused by fluid build up in the skull
	hyper-	greater than or more than normal
	hypertelorism	excessive width between two bodily parts or organs (usually used to describe a broadened space between the eyes)
	hypertonia	stiff muscles
	hypo-	less than or smaller than normal
	hypotonia	floppy muscles
	hypoplasia	incomplete, arrested or underdevelopment of an organ or tissue
	hypoxia	too little oxygen
I
	iatrogenic	caused by the physician or by the treatment.
	icthal	during an actual seizure. (a seizure is an ictal event)
	infantile spasm (IS)	bouts of sudden bilateral contraction of the muscles of the neck, trunk and extremities with sudden flexion of the arms and legs - also known as West's syndrome
	Isolated Lissencephaly Sequence (ILS)	a brain showing agyria and/or pachygyria but with no other symptoms
J
	J-tube	a feeding tube that bypasses the stomach completely and goes straight to the small intestine (J=jejunum)
K
	karyotype	a complete set of chromosomes from a cell nucleus
L
	Lennox-Gastaut syndrome	a seizure disorder characterised by multiple seizure types
	LIS1	the name of the gene located on the short arm (p) of chromosome 17 (17p13.3) that is associated with Miller Dieker Syndrome, some cases of ILS and some case of Lissencephaly with Cerebellar Hypoplasia (a)
	Lissencephaly	an umbrella term which encompasses a broad range of different conditions which affect the development of the cerebral cortex, where the surface of the brain appears smooth. See Classical Lissencephaly
	locus	the location on a chromosome, quoted in the form 17p13.3 (17 = chromosome 17, p = short arm)
M
	macrogyri	large gyri
	MEB	Muscle-Eye-Brain disease. Also, the Muscle-Eye-Brain disease gene. Located on chromosome 1 at 1p32-34
	Miller-Dieker syndrome	agyric and/or pachgyric brain with other symptoms, generally bitemporal hollowing, prominent forehead, short nose with upturned nares, prominent upper lip, thin vermilion border of the upper lip, and small jaw.
	microcephaly	small head circumference
	microdeletion	a small part of a gene or chromosome that is missing
	microencephaly	small brain size
	micrognathia	small chin
	midline	the midline is the line in the body that divides left from right.
	monosomy	a single chromosome when there would normally be two
	MRI (scan)	Magnetic Resonance Imaging - a sophisticated scanning technique for viewing internal organs. MRI produces better images than CT.
	myelin	the insulating coating around the axons of nerve cells
N
	nares	nostrils
	neuronal migration disorder (NMD)	a disorder where the cells in the brain do not move to their correct position during its developmental phase
	NUDEL	a protein that forms a key part of the neuronal migration process
	nystagmus	a wobble in the eye
O
	occipital lobe	the rear part of the cerebrum
	opercularization	The failure of the operculum (like a lid) to cover the sylvian fissure. Operculum(noun): any of several parts of the cerebrum bordering the sylvian fissure and concealing the insula
	-otomy	cut into
P
	pachygyria	a brain showing abnormally large convolutions or folds (gyri)
	palpebral fissures	eyelid fissure
	parietal lobe	the mid upper part of the cerebrum
	perisylvian region	a region near the sylvian fissure
	perivascular spaces	spaces around blood vessels
	phenotype	a set of observable characteristics of an individual or group resulting from the interaction of its genotype with its environment.
	philtrum	the vertical groove on the median line of the upper lip
	Platelet-activating factor (PAF)	a sub-unit of the LIS1 gene
	polyhydramnios	excessive amount of amniotic fluid
	polydactyly	more fingers or toes than normal
	polymicrogyria (PMG)	a cortical malformation in which the cortex has many small gyri. There are different varieties (or syndromes) of PMG: Bilateral diffuse PMG (spares occipital pole) Bilateral frontal PMG (BFP) Bilateral perisylvian PMG (BPP) Bilateral parieto-occipital PMG (BPOP) Bilateral mesial occipital PMG (BMOP)
	ptosis	prolapse of an organ - drooping of the upper eyelid from paralysis
	pyramidal cells	cells found in the cortex of the brain
	pyramidal signs	spasticity and paralysis of body muscles. The word pyramidal refers to the "pyramidal tract", which is the main pathway from the brain to the spinal cord to the muscles that controls fine movements.
Q

R
	recessive (autosomal -)	two copies (one from the mother, one from the father) must be mutant to get the disease. (see dominant)
	RELN	gene that is implicated in Lissencephaly with Cerebellar Hypoplasia (b). Located at 7q22
	ring chromosome	an abnormal chromosome caused by a break in both arms of the chromosome, the ends of which unite leading to the formation of a ring.
S
	scolios	a lateral curvature of the spine
	seizure	disordered electrical activity in the brain which usually results in temporary loss of conciousness
	sequencing (DNA -)	testing which looks at the finest details of a chromosome or gene
	status epilecticus	patient does not regain conciousness between seizure attacks
	strabismus	deviation of the eye which the patient cannot overcome
	subcortical band heterotopia (SBH)	an X-linked disorder more often found in females and is a milder form of lissencephaly. Also known as 'double cortex' (DC) syndrome
	subcortical laminar heterotopia (SCLH)	See subcortical band heterotopia
	sulci	grooves on the surface (cortex) of the brain
	sylvian fissure	a major groove on the outer sides of the cerebrum
	syndrome	a group of concurrent symptoms of a disease
	syndactyly	joined fingers or toes (webbed)
T
	telomeric	near to the telomere (the end of a chromosome arm)
	temporal hollowing	a narrowing of the head at the temples
	tonic clonic seizures	loss of consciousness with generalised convulsions (also known as grand mal)
	translocation	one part of a chromosome is swapped over with another part of a chromosome
	type I and II lissencephaly	old terminology, I = Classical Lissencephaly, II = Cobblestone Lissencephaly, (WWS/MEB)
U

V
	ventricle	a hollow area in the brain containing fluid
W
	Walker-Warburg syndrome	a disorder which shows lissencephaly, malformations of the back portion of the brain (cerebellum), abnormalities of the retina of the eye, and progressive degeneration and weakness of the voluntary muscles (congenital muscular dystrophy) and, in some cases, encephalocele.
	white matter	cellular material lying beneath the cortex that provides communications between parts of the brain (composed of myelinated and unmyelinated axons)
XYZ
	X linked	a genetic defect that is associated with the X chromosome
	XLIS	see DCX

Correct an entry or add a new entry here. I will add it to the glossary as soon as I can. Please leave your Email address as well - thanks.

Abbreviation	Meaning
CSF	cerebrospinal fluid (clear fluid that surrounds the brain and spinal cord)
DSM	Diagnostic and Statistical Manual for Mental Disorders (This is the reference that defines the criteria for diagnosing disorders such as Autism, etc)
ILS	Isolated Lissencephaly Sequence
LCH	Lissencephaly with Cerebellum Hypoplasia or Cerebro-Cellular Lissencephaly
LGS	Lennox-Gastaut Syndrome
MDS	Miller-Dieker Syndrome
MEB	Muscle-Eye-Brain Disease (also the name of the MEB gene)
MLIS	Microlissencephaly
MSG	Microcephaly with Simplified Gyral Pattern or Microgyrencephaly
NRS	Norman-Roberts Syndrome
PMG	Polymicrogyria
PLS	Partial Lissencephaly Sequence (obsolete term)
SCH	Schizencephaly
SBH	Subcortical Band Heterotopia
WWS	Walker-Warburg Syndrome
XLAG	X-linked lissencephaly with ambiguous genitalia