Question | Answer |
present at birth | congenital |
presence of extra chromosome within a cell | trisomy |
an example of trisomy is having | three of a given pair of chromosomes instead of usual pair |
condition of a cell in which one chromosome of homologous pair is missing | monosomy |
nondisjunction can lead to the chromosomal abnormalities of | trisomy & translocations |
individuals with Turner's syndrome have chromosomes of the configuration | 45, X |
Triple X syndrome can be associated with | decreased mental capacity |
Fragile X syndrome is a major cause of | mental deficiency |
x-linked autosomal diseases can become symptomatic in | males |
trisomy of 12 autosomes will not be compatible with | full-term pregnancy |
depending on genetic makeup, an embryo will be more or less susceptible to malformation from | environmental factors |
culture of amnionic cells is important in order to | determine karyotype |
chorionic villus sampling provides the same information as | amniocentesis |
transfer of piece of one chromosome to a nonhomologous chromosome | translocation |
congenital syndrome usually caused by absence of one X chromosome in the female | Turner syndrome |
congenital syndrome caused by extra X chromosome in male | Klinefelter syndrome |
Klinefelter syndrome is characterizes by | testicular atrophy, sterility, feminine body configuration, & subnormal intelligence |
congenital syndrome caused by extra chromosome 21 | Down syndrome |
change in structure of gene, which may alter its functions | gene mutation |
abnormal hemoglobin that crystallizes under reduced oxygen tension | sickle hemoglobin |
congenital malformation; absence of brain, cranial vault, & scalp as result of defective closure of neural tube | anencephaly |
incomplete closure of vertebral arches over spinal cord | spina bifida |
protrusion of meninges & neural tissue through spina bifida defect | cystic spina bifida |
protein produced by fetal liver early in gestation | alpha fetoprotein |
alpha fetoprotein is also sometimes produced by | tumor cells |
alpha fetoprotein level is elevated in amniotic fluid when | fetus has neural tube defect |
one X chromosome is inactivated | Lyon Hypothesis |
in males one copy of most genes is on X chromosome, & inheritance of these genes is called | X-linked |
man will transmit one copy of each X-linked gene | to his daughters and none to his sons |
a woman will transmit one copy of each X-linked gene | to each daughter or son |
environmental factors can affect | expression of some genes |
examples environmental factors that can influence a child's development include: | nutritional patterns and health care |
result from abnormalities of individual genes on the chromosomes | genetically determined diseases |
some abnormalities of individual genes on the chromosomes, arise spontaneously, while others may be caused by | environmental teratogens |
any agent or factor that induces or increases the incidence of abnormal prenatal development | teratogen |
permanent transmissible change in genetic material, usually in single gene, although sometimes used to include gross alterations in chromosomal structure | mutation |
caused by abnormalities in an individual’s genome | genetic or hereditary disorders or diseases |
any abnormality present at birth | congenital disease or malformation |
chromosomal abnormalities, abnormalities of individual genes, intrauterine injury, or environmental factors | factors in congenital malformations |
2-3% of all newborn infants have | congenital defects |
additional 2-3% of developmental defects are demonstrated | later as infants grow older |
25% to 50% spontaneously aborted embryos, fetuses, and stillborn infants have | major congenital malformations |
failure of homologous chromosomes in germ cells to separate in first or second meiotic division | nondisjunction |
nondisjunction may involve either sex chromosomes or | autosomes |
nondisjunction causes abnormalities in distribution of chromosomes between | germ cells |
in nondisjunction, one of two germ cells has an extra chromosome while the other | lacks a chromosome |
chromosome breaks during meiosis and broken piece is lost | deletion |
variations in normal number of sex chromosomes are often associated with some reduction of | intelligence |
directs masculine sexual differentiation, associated with male body configuration regardless of number of X chromosomes present | Y chromosome |
no significant effect as it mainly carries genes concerned with male sexual differentiation | extra Y chromosome |
body configuration is female | absent Y chromosome |
has little effect (one X chromosome is inactivated) | extra X chromosome |
has adverse effects on male development | extra X chromosome in males |
extra X chromosome | Triple X Syndrome |
extra Y chromosome | XYY Syndrome |
most common chromosome abnormalities, in the female | Turner Syndrome & Triple X Syndrome |
most common chromosome abnormalities, in the male | Klinefelter’s Syndrome & XYY Syndrome |
Fragile X Syndrome causes | x-linked mental deficiency |
not related to either excess/deficiency of sex chromosomes & associated with a characteristic abnormality of X chromosome | Fragile X Syndrome |
as a major cause of mental deficiency Fragile X Syndrome is second to | Down syndrome |
results in the loss of several genes that development is generally not possible and the embryo is aborted | absence of an autosome |
may be compatible with development but usually results in multiple severe congenital abnormalities | deletion of a small part of an autosome |
most common chromosomal abnormality, an autosomal trisomy | Down syndrome |
Down syndrome is an autosomal trisomy of | small chromosome 21 |
in Down syndrome extra chromosome 21 acquired as part of the | translocation chromosome |
most common chromosomal abnormality: 1:600 births/manifestations: mental deficiency, cardiac malformation, major defects in other organ systems | nondisjunction occurring in zygote |
Cleft lip and palate; abnormal development of skull, brain, and eyes; congenital heart defect; polydactyly is caused by | trisomy of chromosome 13 |
associated with multiple severe congenital abnormalities | trisomy of chromosome 18 |
are usually fatal in the neonatal period or in early infancy | both 13 and 18 trisomies |
leads to formation of gametes with an extra or missing chromosome. | nondisjunction in meiosis |
occurs in small number of persons with Down syndrome | translocation Down syndrome |
in translocation Down syndrome ___ fused with chromosome 14 or another chromosome | chromosome 21 |
in translocation Down syndrome total number of chromosomes not increased but genetic material is equivalent to | 47 chromosomes |
translocation Down syndrome translocation occurred accidentally during gametogenesis when | both parents have normal chromosome cells |
parent is capable of transmitting abnormal chromosome to his or her children resulting in translocation Down syndrome | 14/21 carrier in one of the parents |
translocation chromosome is not always transmitted normal fetus, child becomes carrier, nonviable fetus, Down Syndrome can occur when | female carrier |
most hereditary diseases are transmitted | on autosomes |
few hereditary diseases are carried on | sex chromosomes |
autosomal dominant inheritance, autosomal recessive inheritance, codominant inheritance, X-linked inheritance are all possible for transmission of | genetically determined diseases |
3rd–8th week after conception: embryo is most vulnerable to ___ ___ as organ systems are still forming | maternal infections |
combined effect of multiple genes interacting with environmental agents | multifactorial inheritance |
test to determine biochemical abnormalities in fetal cells i.e.: chromosomal abnormalities, biochemical abnormalities, analysis of DNA | examination of fetal cells |
tested because products secreted into fluid by fetus that may indicate fetal abnormality | examination of amniotic fluid |
test used to detect major structural abnormalities, i.e. structural abnormalities of nervous system, hydrocephalus, obstruction of urinary tract, failure of kidneys to develop, failure of limbs to form normally | ultrasound examination |
examples of major structural abnormalities of nervous system | anencephaly &; spina bifida |
determination of biochemical abnormalities by analysis of DNA of fetal cells | fetal DNA analysis |
tests used to determine fetal DNA analysis | amniocentesis & chorionic villus sampling |
amniotic fluid for study, usually performed between the 14th and 18th week of pregnancy | transabdominal amniocentesis |
prenatal detection of chromosomal abnormality in women over age 35 due to higher incidence of Down syndrome in infants born to older women | primary use of transabdominal amniocentesis |
frond-like structures that form part of placenta and attach to lining of uterus | Chorionic villi |
can be performed earlier than amniocentesis & carries less risk from abortion if parent decides to terminate pregnancy in case of congenital abnormality | advantages of chorionic villus sampling |
more difficult technically than amniocentesis & complications include spontaneous abortion, limb deformities in fetus | disadvantages of chorionic villus sampling |