Genetics and Genomic in Maternal Newborn Care

genes

A unit of heredity passed down from parent to child and used to determine some trait of the offspring.

anomaly

A thread-like framework composed of nucleic acids and proteins present in the majority of living cells' nuclei and responsible for carrying genes, which carry genetic information.

autosomal

Refers to a chromosome type other than sex chromosomes.

genetics

The research into the herdity & uniqueness of inherited features.

aneuploidy

• An imbalanced chromosomal complement caused by one or more extra or missing chromosomes.

• Factors:

  • high maternal age, presence of prior trisomy, unexpected recombination, higher BMI, smoking, radiation, folic acid deficiency, smoker

humans have how many chromosomes?

46

mitosis

A cell division process that produces two daughter cells with the same number and type of chromosomes as the parent nucleus.

meiosis

Division of a cell into four daughter cells, each containing half as many chromosomes as the parent cell.

haploid

single set of chromosomes being present

trisomy

• syndrome in which there is an extra copy of a chromosome in the cell nucleus = resulting in developmental problems

• more survivable than monosomies

homologous

a pair of chromosomes having the same structure or pattern

monosomy

diploid chromosomal complement in which one (typically the x) chromosome is missing its homologous (corresponding) companion

palmar crease

a line running across the palm of the hand

duplications

A kind of mutation in which a DNA segment, ranging in size from a few bases to a major chromosomal region, is produced in one or more copies.

ring chromosome

A circular structure that results from a chromosome's broken ends fusing together after it breaks in two.

isochromosomes

A structural anomaly in which the chromosome arms are mirror reflections of one other.

deletions

A kind of mutation in which a DNA segment loses one or more nucleotides.

translocation

Happens when a chromosome splits and the two broken pieces reattach to separate chromosomes.

inversions

Occur when a segment splits off and rejoins the same chromosome in the opposite direction.

Trisomy 21 (Down Syndrome)

• wide ranging physical & intellectual anomalies

• increases with maternal age

• 75% result in fetal/embryonic death

• lifespan of 47 years

• >35 years = more likely

• greater risk for Alzheimer's Disease

Trisomy 21 (Down Syndrome)
Characteristics

• Flat facial appearance, specifically the nose

• Eyes wide set with upward slant

• Shorter neck

• Smaller ears

• Protruding tongue

• Smaller hands and feet

• Single palmar crease

• Weak muscles due to poor tone

• Conditions affecting vision & hearing

• Sleep Apnea

• Common congenital heart defects: tetralogy of Fallot, atrioventricular septal defect (AVSD), ventricular septal defect (VSD), patent ductus arterioris (PDA)

• GI Problems: Duodenal Atresia, (due to hypertonia)

• Autoimmune disorders: leukemia

• Endocrine: hyperthyroidism, >risk for obesity & diabetes

• Respiratory: higher rate of respiratory infections (bc of protruding tongue)

• at risk for: feeding problems, swallowing, aspiration because it affects feeding-related behaviors (attentiveness, coordination, sucking, swallowing)

Chromosome Structure

• two short arms (p arms)

• two long arms (q arms)

• centromere→holds arms together, gives distinctive shape, idnetify wher each gene is located

• telomeres→contain sections of DNA, end of chromosome, protect the chromosomes while DNA rep occurs

centromere

holds arms together, gives distinctive shape, idnetify wher each gene is located

telomeres

contain sections of DNA, end of chromosome, protect the chromosomes while DNA rep occurs

Turner Syndrome

in females, 1 every 2000-2500 live female births

Turner Syndrome
Characteristics

• Short stature

• Wide chest

• Low hair line

• Early loss of ovarian function

• Lymphedema

• Amenorrhea

• Structural kidney defects

• Structural heart defects

Klinefelter Syndrome

• 1 in 500-1000 male births

• life expectancy is marginally shortened

• Characteristics:

  • Increased height

  • Long extremities

  • Female hair distribution

  • Small testes

  • Infertility

  • Delayed puberty

  • Developmental delay

  • Increased risk for breast cancer

Triple X Syndrome
Manifestations

• 1 in 1000 female births

• tall stature, learning disabilities, muscular weakness, and kidney defects. Like Klinefelter syndrome, prognosis is determined by the clinical manifestations and treatment.

XYY Syndrome

• 1 out of 1000 male briths

• Characteristics:

  • Increased height

  • Potential learning disabilities

  • Delayed speech and language skills

  • Weak muscle tone

  • Hand tremors

  • Asthma

  • Seizures

  • Scoliosis

  • Behavioral and emotional difficulties

Dominant

• Fragile X syndrome

• Huntington's disease

• Marfan syndrome

Recessive

• Cystic fibrosis

• Hemophilia

• Sickle cell disease

Ultrasound, Blood Test, Placental Biopsy

First-trimester (10-13 weeks)

Cell Free DNA

• blood sample

• screen conditions arising from chromosomes

• as soon as 10 weeks gestation-13 weeks

Chronic Villus Sampling (CVS)

• uses a placental biopsy to perform genetic testing

• high risk: >35 w/ family history of aneuploidy

• in the placenta

• invasive

• 10-13 weeks

Nuchal Translucency Testing

• performing an ultrasound to measure the posterior fetal neck for the presence of a fluid collection

• 11-13 weeks

Quad Screen

• blood test that calculates blood concentrations of four separate chemicals (alpha fetoprotein (AFP), human chorionic gonadotropin (hCG), estriol, inhibin-A)

• high risk: family history of genetic anomalies, >35

• 15-22 weeks

Alpha-Fetoprotein (AFP) Testing

• performed on venous blood drawn from the pregnant client

• predict the likelihood of the fetus having an anomaly

  • spina bifida

  • trisomy 21

  • trisomy 18

• 14-22 weeks

Anatomy Scan

• looks for significant physical problems in the spine, face, heart, abdomen, limbs

• structural anomalies

• 18-22 weeks

Amniocentesis

• invasive

• diagnostic

• to confirm or rule out various inherited or genetic concerns

• inserting needle into amniotic sac

• 3rd trimester

Cardiac

• CCHD (cardiac congenital heart defects)

• pulse ox on right side (preductal)

• one on lower extremities (postductal)