Overview

• Patau’s Syndrome ⇒

  • Trisomy 13. 80% die in first month of life.
  • Features → microcephaly, microphthalmia, cleft lip/palate, polydactyl (extra fingers).
  • Ix → USS analysis in 2nd trimester. Chromosomal analysis from amniocentesis/cffDNA (NIPT).
    • Quradruple Test → low AFP, low oestriol, low HCG, high inhibin. (main difference between patau/edwards and downs, is the low HCG)

• Edward’s Syndrome ⇒

  • Trisomy 18. (18WARDS)
  • Features → low birth weight, small mouth, low-set ears, ‘rocker-bottom’ feet, overlapping fingers.
  • Ix → USS analysis in 2nd trimester. Chromosomal analysis from amniocentesis/cffDNA (NIPT).
    • Quradruple Test → low AFP, low oestriol, low HCG, normal inhibin.

• Down’s Syndrome ⇒

  • Trisomy 21.
  • Features → hypotonia, brachycephaly, short neck, short stature, flattened face/nose, prominent epicanthic folds, upward sloping palperbral fissures, sandle gap deformity, single palmar crease.
  • Complications → learning disability (autism spectrum disorder), recurrent otitis media, deafness, visual problems, congenital cardiac defects (AVSD, ASD, VSD, PDA, tetralogy of Fallot), alzheimer’s, subfertility, hypothyroidism, atlanto-axial instability (if participating in sports that may carry increased risk of neck dislocation).
    • Duodenal Atresia → narrowing of the duodenum, causing bilious vomiting after feeding. Mx = duodenoduodenostomy**.**
  • Antenatal Screening for Down’s Syndrome:

    • Combined Test (ULTRASOUND + BLOODS) → first line, performed 11-14 weeks gestation. Nuchal translucency (high) + bHCG (high) + PAPPA (low).

    • Triple Test (ONLY BLOODS) → 15-20 weeks gestation. bHCG + AFP (low) + oestriol (low). (Isolated AFP Rise = neural tube defect)

    • Quadruple Test → 15-20 weeks gestation. Triple test + inhibin A (high).

      <aside> 💡 Down’s → HI (high HCG, high Inhibin).

      </aside>

    • If risk from these tests is greater than 1 in 150, woman is offered a second screening test (NIPT) or a diagnostic test (CVS [11-14 weeks gestation] or amniocentesis [15-20 weeks gestation]).

  • Management:
    • Urgent PCR for trisomy 21.
    • Echocardiogram → congenital heart defects occur in 45% (mainly AVSD).
    • FBC and Blood Film → 10% have transient abnormal myelopoiesis.
    • MDT Approach.
    • Hearing Screening Test.
    • Speech and Language Therapist.

• Turner’s Syndrome ⇒

  • Only one X chromosome present in females (45,XO).
  • Features → short stature, shield chest, webbed neck, bicuspid aortic valve (= ejection systolic murmur) (MOST ASSOCIATED - 15%), coarctation of the aorta (5-10%) (RISK OF AORTIC DISSECTION - leading cause of mortality in those with turners), primary amenorrhoea.
  • Elevated FSH and LH + reduced Oestrogen (Hypergonadotrophic Hypogonadism).

• Klinefelter’s Syndrome ⇒

  • 47XXY in Males.
  • Features → infertility, hypogonadism (small testicles), gynaecomastia (+ feminised physique).
  • Elevated FSH and LH + reduced testosterone (Hypergonadotrophic Hypogonadism).

• Fragile X Syndrome ⇒

  • Trinucleotide repeat disorder.
  • Males → learning difficulties, MACROCEPHALY, large low set ears, long thin face, high arched palate, macroorchidism (big testes), hypotonia, autism, mitral valve prolapse (COMPLICATION - PANSYSTOLIC MURMUR).
  • Females → have one fragile chromosome and one normal X chromosome therefore may be mild.
  • Diagnosis → made antenatally by CVS or amniocentesis.

• Noonans’s ⇒

  • Features (PP) → pectus excavatum, pulmonary stenonsis.
  • ‘Male version of Turner’s’ (Webbed Neck + Short Stature)

• Prader-Willi ⇒

  • Chr15 Deletion.
  • Features → hypotonia, hyperphagia, almond-shaped eyes.
  • Imprinting = expression of gene influenced by sex of parent who has transmitted it (from father = PWS, from mother = angelman syndrome).

• Williams Syndrome → an elfin appearance, supravalvular aortic stenosis.

• Down’s vs Edwards vs Patau

Making Diagnosis

Clinical Features

Investigations

Management Plan