How Do Mutations Affect Health and Craniofacial Development? Flashcards
What are multifactorial diseases caused by?
NOT a single mutation, but by interacting genetic and environmental risk factors
What results from failed palatogenesis?
a cleft lip and palate
Where do the neural crest cells lay?
on the dorsal side of the neural tube
What are some characteristics of patients with Down syndrome that are not craniofacial-related?
- low muscle tone
- small stature
- cognitive delay
- transverse palmar crease*
___ or Mendelian disorders are mutations in a single gene and can be dominant or recessive.
Single-gene disorders
What are the 3 ways Down syndrome can happen?
Nondisjunction
Mosaicism
Translocation
What happens in the translocation of chromosome 21 to cause Down syndrome?
a full or partial copy of chromosome 21 attaches to another chromosome (usually 14)
What is the most common cause of Down syndrome?
Nondisjunction (95%)
What chromosome is affected in Cri-du-Chat syndrome?
chromosome 5 (partial loss)
What questions MUST be asked of a patient with Down syndrome in clinic?
What heart defects do you have?
Do you have any spinal problems?
How many chromosomes do those with mosaic Down syndrome have?
some cells have 46 and some cells have 47
Where do the cells from the palate and jaw regions originate from?
the neural crest mesenchyme and rhombomeres 1 and 2
What is the Simian crease?
a transverse palmar crease
Which chromosomal rearrangements are likely to cause disease?
only those that change the copy number of genes or break apart an important gene
How many mutations is the average child born with not present in the parents?
100-200
What forms the primary palate in a developing embryo?
the median palatal process (derived from medial nasal processes and frontonasal process)
What are chromosomal rearrangements caused by?
chromosome breakage or by recombination between mispaired chromosomes during meiosis
What are some facial defects seen in patients with Cri-du-Chat syndrome?
- wide set eyes (hypertelorism)
- low-set ears
- small jaw (micrognathia)
- rounded/moon face
- epicanthal folds
- broad nasal bridge
- downward slanting eyes
What are the key facial characteristics of Down syndrome?
- upslanting eyes
- flattened nasal bridge
- Brushfield spots (eyes)
- epicanthal fold
- short neck
- low-set small folded ears
What is the nasal septum derived from in the basic steps of palatogenesis?
frontonasal prominence
What are some examples of multifactorial diseases?
allergies, diabetes, coronary heart disease
80% of children born with Down sydrome are born to what kind of mothers?
technically younger mothers due to higher birth rates among younger women
Where do most cases of aneuploidy originate from?
female meiosis I (risk increases with age)
The 1 in 50 infants born with a diagnosable condition can be attributed to what?
1 single mutation
