Genetics and Common Craniofacial Syndromes Flashcards
Genetic material contained where in cell?
nucleus
What communicates with the endoplasmic reticulum (a complex system of membranes that control transport of proteins and lipids)
nucleus
substance that carries hereditary info. Its a nucleic acid made of building blocks called nucleotides arranged int antiparallel double helixes.
DNA
the process of creating 2 identical DNA molecules from one.
Replication- the two double strands separate and a newly synthesized strand is added to each original. Its a complex process but it takes place quickly for rapid cell division and growth.
How many nucleotides must be precisely matched for each cell division?
3.5x10 to the 4th
what is a change in the sequence referred to as?
a mutation
what transports genetic info from the nucleus to cytoplasm?
RNA- a single stranded molecule rather than a double helix
what is the process called that creates RNA? its created as a single complementary strand of DNA template
Transcription
Flow of genetic information proceeds from what through what to RNA?
DNA through transcription
linear double helix strands of DNA?
Chromosomes
DNA is organized into how many chromosomes?
46
Each of the 22 chromosomes has 2 copies called:
Autosomes
Chromosomes can be seen in a
karyotype (a visual profile)
The 23rd pair are called
sex chromosomes- aid in determining gender
Loss of one copy results in
monosomy
gain of one extra copy is called
trisomy
the presence of cells with two or more different genetic contents in a single individual
Mosaicism
Chromosomal abnormalities can include:
deletions, duplications, inversions, and translocations
what is autosomal recessive inheritance?
all people carry genes with mutations capable of causing dz.
inheriting 2 copies of each gene and one copy that functions is
sufficient
carriers are individuals that have one copy of the gene by no
abnormalities
occur only when mutations are present in both genes and males and females are affected equally.
Autosomal Recessive Conditions
Occurs when mutations are present in either the 2 copies of a gene. (often show one parent is affected(
Autosomal Dominant Inheritance
Many autosomal dominant conditions have variable
expressivity
X-linked inheritance mutations are on the
x-chromosome
who are most frequently affected because they only receive one x
males
What type of dominant inheritance is rare?
x-linked dominant inheritance-
all daughters of affected males inherit the disorder.
An interaction of multiple genes with environmental influences…
Multifactorial inheritance-
environmental factors that increase the risk of birth defects; ethanol, cigarettes, anti-epileptic meds, maternal DB, congenital infections
Teratogens.
What is the purpose of a genetics eval?
- make a dx
- dt hx of the condition to assist with medical and mx for medical and developmental issues
- dt recurrence risks for parents
- provide genetic psychosocial counseling
what occurs in a genetics eval?
- Prenatal history-essential component to determine if fetus had any exposure to a teratogen
- Medical history- important to note any medical concerns
- Developmental history-milestones for development (did they roll over, babble?)
- Feeding history-feeding difficulties how/when resolved (did they need a special feeder? G-Tube?)
- Family history-Most important component of a genetic evaluation for tracking traits etc.
- Physical examination (look at everything)
- Lab and imaging studies if needed
- Genetic counseling (genetic testing for bloodwork)
- Psychosocial counseling (likelihood of it being passed on)
what is a common birth defect?
CL with or w/o CP
which side is more common for cleft?
Left
left and right sided clefts occur more frequently than
bilateral CL or CP
