In a 2‑week‑old preterm infant with flat facial profile, epicanthal folds, almond‑shaped eyes, single deep palmar crease, sandal‑gap toe spacing, Brushfield spots on the iris, protruding tongue, hypotonia, and a holosystolic murmur at the left lower sternal border, what is the most likely diagnosis and what initial diagnostic and management steps are recommended?

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Last updated: October 5, 2026 • View editorial policy

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Down Syndrome (Trisomy 21)

This infant has Down syndrome, and you should immediately confirm the diagnosis with karyotype analysis (which appears already pending from the hospital blood draw), perform echocardiography to evaluate the cardiac defect, initiate feeding support to address failure to thrive, and begin systematic screening for associated anomalies according to established Down syndrome guidelines.

Clinical Diagnosis

The constellation of findings is pathognomonic for Down syndrome 1, 2:

  • Craniofacial features: Flat facial profile, almond-shaped eyes with epicanthal folds, Brushfield spots (white iris spots), protruding tongue, small ears
  • Extremity findings: Single deep palmar crease (simian crease), clinodactyly (curved pinky), sandal-gap deformity (wide space between 1st and 2nd toes)
  • Systemic findings: Hypotonia ("floppy"), poor feeding, lethargy
  • Cardiac abnormality: Holosystolic murmur with thrill suggesting ventricular septal defect (VSD) or atrioventricular septal defect (AVSD)

Clinical diagnosis accuracy is 90% for standard trisomy 21 and 100% for translocation variants, though only 37.5% for mosaic forms 2. The six most frequent features—simian crease, sandal gap, epicanthic folds, hypotonia, upslanting palpebral fissures, and protruding tongue—are present in this patient 2.

Immediate Diagnostic Steps

1. Confirm Karyotype

The hospital already drew blood for karyotyping (which the mother mentioned). This will differentiate:

  • Standard trisomy 21 (95% of cases—sporadic nondisjunction)
  • Robertsonian translocation (1.45%—important for recurrence risk counseling)
  • Mosaic variants (3.85%—may have milder phenotype) 1

2. Cardiac Evaluation—URGENT

Perform echocardiography within 48 hours. Congenital heart disease occurs in 40% of Down syndrome cases 1. The holosystolic murmur with thrill and S4 gallop strongly suggests:

  • Ventricular septal defect (most common)
  • Atrioventricular septal defect (endocardial cushion defect)
  • Other structural anomalies

Cardiac defects significantly impact mortality and require early surgical planning 1, 3.

3. Address Failure to Thrive—URGENT

The infant has lost 7 ounces (12.7% weight loss from birth weight), which is concerning:

  • Feeding evaluation: Assess for structural causes (cardiac failure, gastrointestinal anomalies)
  • Lactation consultation: Optimize feeding technique given hypotonia and poor latch
  • Consider supplementation: May need higher-calorie formula or fortified breast milk
  • Monitor closely: Daily weights until weight gain established

Hypotonia and cardiac disease both contribute to poor feeding 1.

Systematic Screening Protocol

Immediate (First 2 Weeks)

Hematologic screening:

  • Complete blood count with differential
  • Screen for transient myeloproliferative disorder (occurs in 10% of newborns with DS)
  • Leukemia risk is increased 20-fold 1

Thyroid screening:

  • TSH and free T4 (NOT just TSH alone—18% of centers incorrectly order serum TFT when screening is sufficient) 3
  • Hypothyroidism is common and affects development

Gastrointestinal assessment:

  • Evaluate for duodenal atresia or Hirschsprung disease (5% incidence) 1
  • Assess stooling pattern and feeding tolerance

Within First Month

Audiology referral (82.2% adherence in recent audits) 3:

  • Hearing loss is common and impacts language development
  • Baseline audiogram needed

Ophthalmology referral (only 23.3% adherence—commonly missed) 3:

  • Evaluate Brushfield spots
  • Screen for cataracts, strabismus, refractive errors

Genetics consultation:

  • Discuss karyotype results and recurrence risk
  • Provide family counseling and resources
  • If translocation found, parental karyotyping needed

Common Pitfalls to Avoid

  1. Delaying cardiac evaluation: The murmur demands urgent echocardiography—do not wait for "routine" cardiology appointment
  2. Inadequate feeding support: This infant's weight loss requires immediate intervention, not just "follow-up in 2 weeks"
  3. Missing ophthalmology referral: This has the lowest adherence rate (23.3%) but is critical for development 3
  4. Ordering wrong thyroid tests: Screen with TSH/T4, not full serum thyroid panel initially 3
  5. Assuming mosaic DS is milder: These cases are often missed clinically and may still have significant complications 2

Parent Communication

Address the mother's concerns directly:

  • Explain that the blood draw was for karyotype confirmation of Down syndrome
  • Acknowledge her observations are accurate and important
  • Provide written resources from Down syndrome support organizations
  • Schedule close follow-up (within 3-5 days) to review karyotype and cardiac results
  • Connect with early intervention services immediately—developmental support improves outcomes

Prognosis discussion: With modern care, individuals with Down syndrome without severe cardiac disease can live beyond 60 years 1. Early intervention for cardiac, feeding, and developmental issues significantly impacts quality of life.

References

2
Research

Accuracy of the clinical diagnosis of Down syndrome.

The Ulster medical journal, 2004

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This information is intended for healthcare professionals. Any medical decision-making should rely on clinical judgment and independently verified information. The content provided herein does not replace professional discretion and should be considered supplementary to established clinical guidelines. Healthcare providers should verify all information against primary literature and current practice standards before application in patient care. Dr.Oracle assumes no liability for clinical decisions based on this content.