Congenital infections & disorders Flashcards
Aneuploid
- Cells deviating from
the multiple of the
haploid number - 23 paired chromosomes
(+) or (−) preceding the
chromosome number
indicates _____
↑ or ↓ whole chromosome in a cell
47, XY+21
Designates a ♂ with 3
copies of chromosome 21
(+) or (−) after the chromosome
number signifies _____
extra or missing material on 1 of the arms of the
chromosome
46, XX, 8q−
Denotes a deletion on the
long arm of chromosome 8
Trisomy: ____
3 of a particular chromosome
Monosomy: _____
Only 1 of a particular chromosome
Examples of structural
chromosomal abnormalities:
- Deletion
- Duplication
- Inversion
- Ring chromosome
- Translocation
- Insertion
Xenobiotics
compounds foreign to nature
Neural Tube Defects
Anencephaly, encephalocele, spina bifida (myelomeningocele), sacral agenesis, & other spinal dysraphisms
Etiology of Neural Tube Defects
- Neural tube develops via closure at multiple closure sites
– Each is mediated & affected by different genes & teratogens
– Usual cause → Folate Deficiency - Combined with genetic &/or environmental factors
Neural Tube Defects Presentation
- Lesions at birth
– Extent of neurologic deficit depends on the lesion level (Open vs. subtle skin covering)
Diagnosis of neural tube defects and importance of early diagnosis
- Prenatal screening
– Ultrasound
– Maternal alpha-fetoprotein (AFP) - Specific globulin from the yolk sac, GI tract, & liver
- In maternal serum, amniotic fluid, & fetal plasma
– AFP Concentration: Maternal serum AFP < Amniotic fluid or Fetal plasma
Ultrasound Screening (US) guidelines for neural tube defects
- Transabdominal → 18-20 weeks
– Detection rate = 92-100% for NTD - Transvaginal → 12-14 weeks
– Detection rates vary
44% (spina bifida) >90 (anencephaly)
Management of Myelomeningocele (Spina Bifida)
– Possible fetal surgery to stop
leakage of spinal fluid & possibly
prevent hindbrain herniation & hydrocephalus
– Delivery
* No benefit of pre-labor cesarean delivery
* Meningocele is unlikely to cause dystocia
Management of anencephaly
- Poor prognosis
– Most are stillborn or die shortly after birth - Most pregnancies are terminated or induced
- These infants are poor candidates for organ donation
Management of Encephalocele
- No data available
- Vaginal delivery may be safe (small lesion)
– Cesarean delivery (large lesions)
Complications of Myelomeningocele
- Poor prognosis
- Intellectual disability
- Hydrocephalus
- Clubfeet
- Dislocated hips
- Neurogenic bowel & bladder
- Total flaccid paralysis
– Below lesion level
Complications of Encephalocele
- Poor prognosis
- Intellectual disability
Most common craniofacial malformation of the newborn
Cleft Palate
Etiology of cleft palate
- Genetic ~10% have a genetic variant
- Environment (drugs)
- Folate deficiency
1. Maternal smoking
2. Maternal obesity
3. Syndromes
Nursing education for cleft palate
- Difficult* for most infants to generate negative intraoral pressure to suck milk effectively from bottle or breast
- Often can be bottle fed with formula or expressed breast milk with adaptive
feeding equipment
*Some infants may be able to breast feed & the
soft breast tissue will fill gaps & create suction
Management of cleft palate
- When Dx’d prenatally, recommend amniocentesis
- High % of chromosomal abnormalities for this population
- Surgical Repair
– Primary lip repair at 3 months
– Palate repair ~6 months
Phenylketonuria (PKU)
PKU is a d/o affecting the amino acid phenylalanine
* Infants lack phenylalanine hydroxylase (PAH)
* Causes Intellectual disability
Etiology of PKU
- Most cases of PKU are caused
by Phenylalanine hydroxylase
deficiency
– Autosomal recessive inheritance - ↑ serum phenylalanine: Disrupts brain growth,
myelination & neurotransmitter synthesis
Phenylketonuria (PKU) S&S
– Seizures
– Microcephaly
– Behavioral abnormalities
– Irreversible intellectual disability
– Insidious onset (Signs & symptoms begin
after initiating feeds with breast milk or standard
formula)
PKU diagnosis
- Newborn Screening
– Mass spectrometry
– ↑ phenylalanine concentration
– ↓ tyrosine concentration - ↑ serum & urine concentration of phenylalanine
PKU management
- Restrict dietary phenylalanine
- Consume phenylalanine-free protein substitutes
- Breastfeeding is encouraged under the
supervision of an experienced metabolic
dietitian & is alternated with phenylalanine-free formula feeding
– Breast milk (↓ phenylalanine concentration)
Galactosemia
↑ serum galactose concentration 2° deficiency ≥ 1
* Galactose-1-phosphate uridyl transferase (GALT)
– MOST common & severe
* Galactokinase (GALK)
* Uridine diphosphate galactose 4-epimerase