Chapter 4 Flashcards
Male Chromosome
46 XY male
Female Chromosome
46 XX female
A missing chromosome is called
A missing chromosomes changes the number and causes a trisomy to occur
Three common chromosomal trisomy’s are
Chromosome 13, 18 or 21
Trisomy 13
1 in 25,000 births severe central nervous system malformations, bilateral cleft lip and palate malformed ears Cognitive delays
Trisomy 18
1 in 8,000 births Cognitive delays, growth retardation, low set malformed ears
Trisomy 21
1 in 800 births. Cognitive delays, flat nasal bridge, protruding tongue, simian crease
Simian Crease
First sign of down syndrome with newborn. Named after feature on ape hands.
Brain Development (Approximately Week 3)
- Development of the brain and spinal cord begins early in week 3 of gestation
- Neural tube closes at approximately day 22
- Days 22-23 the rostral two thirds of the neural tube represents the future brain
- The caudal one third represents the future spinal cord
Brain Development (Approximately Week 4)
Three primary brain vesicles form during week 4
Cranium bifidum
failure in the cerebral collom for fusing , Bone fusion is prevented in the posterior midline of the skull
Brain or spinal cord protrudes through the opening
Brain Development (Approximately Week 5)
Prosencephalon-telencephalon, diencephalon
Rhombencephalon-metencephalon and mylencephalon
Mesenecephalon does not divide
spina bifida
Spina bifida is a birth defect where there is incomplete closing of the backbone and membranes around the spinal cord.
Three main types of spina bifida
There are three main types: spina bifida occulta, meningocele, and myelomeningocele.
spina bifida occulta
Occulta is Latin for “hidden”. This is the mildest form of spina bifida.[17] In occulta, the outer part of some of the vertebrae is not completely closed.[18] The splits in the vertebrae are so small that the spinal cord does not protrude. The skin at the site of the lesion may be normal, or it may have some hair growing from it; there may be a dimple in the skin, or a birthmark.[19] Unlike most other types of neural tube defects, spina bifida occulta is not associated with increased AFP, a common screening tool used to detect neural tube defects in utero. This is because, unlike most of the other neural tube defects, the dural lining is maintained.
meningocele
A posterior meningocele (pronounced /məˈnɪŋɡəˌsil/) or meningeal cyst (pronounced /mɪˈnɪndʒiəl/ /sɪst/) is the least common form of spina bifida. In this form, a single developmental defect allows the meninges to herniate between the vertebrae. As the nervous system remains undamaged, individuals with meningocele are unlikely to suffer long-term health problems, although cases of tethered cord have been reported. Causes of meningocele include teratoma and other tumors of the sacrococcyx and of the presacral space, and Currarino syndrome.
myelomeningocele
Myelomeningocele, also known as meningomyelocele, is the type of spina bifida that often results in the most severe complications. In individuals with myelomeningocele, the unfused portion of the spinal column allows the spinal cord to protrude through an opening. The meningeal membranes that cover the spinal cord also protrude through the opening, forming a sac enclosing the spinal elements, such as meninges, cerebrospinal fluid, and parts of the spinal cord and nerve roots.
Arnold chiari malformation
Like spinal biffida in the brain- Arnold chiari malformation
hydrocephalus
characterized by large head and very prominent forehead; in many cases brain atrophy; mental deficiency; and convulsions- excess cerebral spinal fluid enlarges the ventricles or blockage does not allow cerebral spinal fluid to drain
syringomyelia
syringomyelia is a generic term referring to a disorder in which a cyst or cavity forms within the spinal cord. This cyst, called a syrinx, can expand and elongate over time, destroying the spinal cord. The damage may result in pain, paralysis, weakness, and stiffness in the back, shoulders, and extremities. Syringomyelia may also cause a loss of the ability to feel extremes of hot or cold, especially in the hands. There is also a disorder that generally leads to a cape-like pain (extreme pain, pressure, and many other painful symptoms in the area where a cape would be) and temperature sensation along the back and arms. Each patient experiences a different combination of symptoms. These symptoms typically vary depending on the extent and, often more critically, to the location of the syrinx within the spinal cord.
microcephaly
Microcephaly is a medical condition in which the brain does not develop properly resulting in a smaller than normal head. Microcephaly may be present at birth or it may develop in the first few years of life. Often people with the disorder have an intellectual disability, poor motor function, poor speech, abnormal facial features, seizures, and dwarfism
microcephaly causes
The disorder may stem from a wide variety of conditions that cause abnormal growth of the brain, or from syndromes associated with chromosomal abnormalities. A homozygous mutation in one of the microcephalin genes causes primary microcephaly.
holoprosencephaly
Incomplete development of midline structures
Fused eyes
Single nasal chamber
Single ventricle
Olfactory bulbs and tracts and corpus callosum are hypoplastic
lissencephaly
Lissencephaly is a set of rare brain disorders where the whole or parts of the surface of the brain appear smooth. The word lissencephaly is derived from the Greek λισσός lissos meaning “smooth” and encephalos meaning “brain”.It is caused by defective neuronal migration during the 12th to 24th weeks of gestation resulting in a lack of development of brain folds (gyri) and grooves (sulci). It is a form of cephalic disorder.
craniorachischisis
Developmental birth defect involving the neural tube
Congenital fissure of the skull and spine
Encephalocele
Hernia of part of brain and meninges through a cranial defect with protrusion of brain matter
Down Syndrome
also known as trisomy 21, is a genetic disorder caused by the presence of all or part of a third copy of chromosome 21. It is typically associated with physical growth delays, characteristic facial features and mild to moderate intellectual disability. The average IQ of a young adult with Down syndrome is 50, equivalent to the mental ability of an 8- or 9-year-old child, but this can vary widely
fragile X
One of the most common causes of cognitive and intellectual impairments
1 in 1500 male births. Symptoms often include mild to moderate intellectual disability. Physical features may include a long and narrow face, large ears, flexible fingers, and large testicles. About a third of people have features of autism such as problems with social interactions and delayed speech
Williams Syndrome
Williams syndrome is a developmental disorder that affects many parts of the body. This condition is characterized by mild to moderate intellectual disability or learning problems, unique personality characteristics, distinctive facial features, and heart and blood vessel (cardiovascular) problems.
