Chromosomal Abnormalities

Advanced maternal age

35yo or older at EDD

Karyotyping

analysis of fetal chromosomes

Sequence:

single defect leading to development of other defects

Syndrome:

group of clinically observable findings that often exist together

Anomaly:

any structural feature that is abnormal

Association:

nonrandom occurrence of at least 3 associated defects

Aneuploid

any abnormal # of chromosomes

Euploid:

normal chromosomes

Diploid:

two complete sets of chromosomes. Humans have 23 pairs = 46 chromosomes

Triploid:

three complete sets = 69 chromosomes

Monosomy:

only one of an individual chromosome. Miss one = 45 chromosomes

Trisomy:

three copies of one individual chromosome. One extra = 47 chromosomes

Mosaic:

: mixed pattern aneuploid

• Chorionic Villi Sampling

Samples placenta for aspiration of trophoblastic cells.

Earliest procedure done TA or TV between 10-12 weeks.

Fetal loss rate 0.8%

• Amniocentesis

Samples amniotic fluid.

15 weeks onward.

US guided TA.

Prior to procedure, identify MVP (max vertical pocket), placental position, and fetal position.

Fetal loss rate 0.5%

Cordocentesis

Percutaneous Umbilical Cord Sampling (PUBS).

Samples fetal blood.

After 17weeks.

US guidance, samples through umbilical cord near insertion into placenta.

Fetal loss rate 0.1%

triple screen evaluates what components

maternal serum alpha-fetoprotein (MSAFP), estriol, and human chorionic gonadotropin (hCG).

AFP is produced in the

yolk sac and fetal liver

Estriol and hCG are produced by

placenta.

Two supplementary proteins that can also be monitored are the

Two supplementary proteins that can also be monitored are the

One of the newer maternal blood test available is

cell-free DNA testing. This simple blood test can reveal gender and is also highly accurate in detecting chromosomal anomalies, including trisomies 21, 18, and 13 and sex chromosome abnormalities, as early as 9 weeks’ gestation

Trisomy 21/ Down’s syndrome

Most common aneuploid.

1 in 800 births.

Risk increases greatly with increased maternal age.

Screening Findings for Trisomy 21/ Down’s syndrome

Elevated hCG and inhibin-A

Low AFP, estriol, and PAPP-A

Sonographic Findings for Trisomy 21/ Down’s syndrome

Absent nasal bone

‣ Flattened profile

‣ Thickened NF

‣ Macroglossia

‣ Echogenic intracardiac focus EIF

‣ Cardiac defects: AV Canal (AVSD)

‣ Duodenal atresia (double-bubble)

‣ Echogenic bowel (can also be cystic fibrosis)

‣ Short limbs

‣ Sandal gap feet

Trisomy 18 Edwards syndrome

Usually fatal

Screening Findings for Trisomy 18 Edwards syndrome

All values decreased

Sonographic Findings for Trisomy 18 Edwards syndrome

‣ Choroid plexus cysts

‣ Strawberry-skull

‣ Micrognathia

‣ Omphalocele

‣ Esophageal atresia

‣ Clenched hands/clinodactyly

‣ Rockerbottom feet

‣ Cardiac defects

Trisomy 13 Patau’s syndrome

Usually fatal

Screening Findings for Trisomy 13 Patau’s syndrome

Non-specific

Sonographic Findings for Trisomy 13 Patau’s syndrome

‣ Holoprosencephaly

‣ Facial abnormalities

‣ Microcephaly

‣ Polydactyly

‣ Omphalocele

‣ Cardiac defects (Hypoplastic Lt heart)

‣ Clubfeet - talipes equinovarus

Monosomy X Turner’s syndrome

usually fatal but has a reported incidence of 1 in 2,500 to 5,000 live female births.

screening for Monosomy X Turner’s syndrome

Low AFP and estriol

With Hydrops: Low hCG and inhibin A Low PAPP-A

Sonographic Findings for Monosomy X Turner’s syndrome

‣ Females

‣ Cystic hygroma

‣ Increased NT

‣ Renal anomalies (horseshoe/agenesis)

‣ Cardiac defects

‣ Nonimmune hydrops

Triploidy

3 sets with total of 69 chromosomes. Usually fatal early.

Screening Findings for Triploidy

High hCG (with molar

Sonographic Findings for Triploidy

‣ Partial molar

‣ Small, low set ears

‣ Syndactyly (fused digits)

‣ IUGR

‣ Cardiac defects

‣ Theca-Lutein cysts

Meckel-Gruber syndromes

PKD,

encephalocele

, microcephaly,

polydactyly

Potters syndrome

Bilateral renal agenesis,

oligo,

pulmonary hypoplasia,

facial anomalies

Beckwith-Wiedemann syndrome

Macroglossia

, large organs

Pentalogy of Cantrell syndrome

Omphalocele,

ectopia cordis,

sternal and diaphragm defects

VACTERL syndrome

Vertebral,

Anorectal,

Cardiac,

Tracheo,

Esophageal,

Renal

, Limb

Amniotic band syndrome

Limb amputations,

facial clefts,

gastroschisis

skeletal defects

Limb Body Wall syndrome

Abdominal wall defects,

scoliosis,

facial,

limb defects

Fetal Alcohol syndrome

IUGR,

microcephaly,

microophthalmos,

cardiac defects,

hypospadias

Kleebattschadel syndrome

Cloverleaf skull due to craniosynostosis (premature fusion of sutures)

Holt-Oram / Heart-Arm syndrome

Heart and upper extremity malformations

Treacher-Collins / Collar

Ears, mandible, and palate malformations