The tumors may cause bumps under the skin colored

•
The tumors may cause bumps under the skin, colored spots,
skeletal problems, pressure on spinal nerve roots , and other
neurological problems.

1-Neurofibromas, café-au-lait, Lisch nodules

NEUROFIBROMATOSIS 1- (von Recklinghausen)
•
Is a tumor disorder that is caused by the
mutation of a gene on chromosome 17 that is
responsible for control of cell division.
•
NF-1 causes tumors along the nervous system.
•
Common symptoms of NF-1 include
•
scoliosis (curvature of the spine),
•
learning disabilities,
•
vision disorders, Lich nodules (
•
and epilepsy.

Cutaneous neurofibromas and
a 'café au lait spot'
Back of an elderly woman with NF-1
Lisch nodules
a pigmented hamartomatous nodular aggregate of
dendritic melanocytes affecting the iris

NEUROFIBROMATOSIS 2-
Bilateral acoustic neuromas and multiple
meningiomas
•
Manifested by the development of symmetric, non-
malignant brain tumors in the region of the cranial
nerve VIII,
•
which is the "auditory-vestibular nerve" that transmits
sensory information from the inner ear to the brain .
•
NF II is caused by mutations of the Merline gene
which seems to influence the form and movement
of cells
•
Many people with this condition also experience
visual problems.

Hereditary Disease Caused by Sex-Linked
Recessive Genes
•
Caused by defective genes carried on the X
chromosome
•
Males affected more than women
•
Males inherit one defective gene on X from
mother to have disorder
•
Females only affected if they inherit 2
defective genes (one from each parent)

Ex. Hemophilia
•
Caused by the inheritance of one recessive gene on
the X (males) or two recessive genes on both X’s
(females)
•
Affects blood – blood does not clot
•
Leads to severely increased risk of bleeding from
common injuries
•
Potentially fatal

3. Chromosomal aberrations (cytogenetic
disorders)
•
alternations in the number or structure of
chromosomes
•
autosomes or sex chromosomes
•
studied by cytogenetics
•
cell cycle arrested in metaphase (colchicin) -
staining by Giemsa method (G-bands) -
photographing - karyotype
•
2 sets of 23 chromosomes
•
22 pairs of autosomes, 2 sex chromosomes (XX or
XY)
•
cytogenetic disorders are relatively frequent ! (1:160
newborns; 50% of spontaneous abortions)

Structural abnormalities
•
breakage followed by loss or rearrangement
•
deletion, translocation
Generally :
•
loss of chromosomal material is more dangerous
than gain
•
abnormalities of sex chromosomes are better
tolerated than autosomal
•
abnormalities of sex chromosomes sometimes
symptomatic in adult age (e.g. infertility)
•
usually origin de novo (both parents and siblings
are normal)

Numerical abnormalities
•
euploidy - normal 46 (2n)
•
polyploidy (3n or 4n) - spontaneous abortion
•
aneuploidy
–
trisomy (2n+1) - 47 - compatible with life
–
monosomy (2n-1) -
•
autosomal - incompatible with life
•
sex chromosomal- compatible with life
•
Deletion
•
Breakage

COMMON CYTOGENETIC DISEASES
•
AUTOSOMES
–
TRISOMY-21 (
DOWN
SYNDROME)
–
8, 9, 13 (Patau), 18 (Edwards), 22
–
22q.11.2 deletion
•
SEX CHROMOSOMES
–
KLINEFELTER
: XXY, XXXY, etc.