15.3 Genetic Conditions, Syndromes, and Trisomies

15.3 Genetic Conditions, Syndromes, and Trisomies

Quick Answer: Use the phenotype to drive the first night of care. Trisomy 21 needs an echo and feeding support. Trisomy 18 and 13 need apnea and feeding plans plus a goals-of-care conversation. Turner and Noonan need heart imaging. Beckwith-Wiedemann is airway plus glucose. Prader-Willi is hypotonia and a feeding tube. CHARGE is choanal atresia until proven otherwise. Leave urea-cycle and organic-acidemia crashes in Chapter 6.

Scope: syndromes here, metabolic IEM in Chapter 6

The Neonatal CCRN Test Plan lists genetic conditions and names metabolic disease, syndromes, and trisomies 13, 18, and 21. OpenExamPrep splits that leaf on purpose. Chapter 6 teaches the inborn-error emergency: stop feeds, give glucose, send ammonia, call the metabolic team. This section teaches recognizable malformation patterns and the postnatal actions they change: how you feed, which heart lesion you expect, why apnea appears, and when the honest nursing job is comfort and shared decisions rather than another procedure by default. Independent practice: /practice/ccrn-neonatal. Pediatric CCRN genetic content is a separate credential at /study-guides/ccrn-pediatric.

You do not delay bag-mask ventilation for a karyotype. You do send the right tests once the infant is pink, and you do tell families what is known versus what is pending.

Trisomy 21 (Down syndrome)

Trisomy 21 is the most common live-born aneuploidy. Expect hypotonia, upslanting palpebral fissures, epicanthal folds, a flat facial profile, single palmar creases, a sandal-gap, and a poor suck. None of those features is mandatory in isolation; the cluster is what you act on.

Cardiac disease is common; atrioventricular septal defect (AVSD) is the signature lesion, with VSD, ASD, and tetralogy also on the list. Obtain an echocardiogram rather than waiting for a murmur. Duodenal atresia (double-bubble) and Hirschsprung disease sit in Chapter 8; mention them here so a trisomy-21 infant with bilious emesis is not treated as “just hypotonic feeding.” Transient abnormal myelopoiesis (GATA1-related) can present with blasts, high white count, and even hydrops—hematology owns the smear, but you own the recognition that this is not ordinary polycythemia teaching from Chapter 7.

Nursing: paced feeding, upright positioning, watch for apnea and pulmonary hypertension if the heart lesion plus hypotonia demand it, and early lactation help. Hypothyroidism is a newborn-screen and later follow-up issue; do not skip the screen. Atlantoaxial instability is not a day-1 NICU intubation trivia item, but document the diagnosis so later procedures are planned.

Trisomy 18 (Edwards) and trisomy 13 (Patau)

Trisomy 18 presents with intrauterine growth restriction, clenched hands with overlapping fingers, rocker-bottom feet, micrognathia, omphalocele in some, and a high rate of heart defects (VSD and polyvalvular dysplasia). Apnea and an absent suck are common. Survival statistics in older series were grim; some infants live longer with intensive support. The nurse’s job is not to quote a single percentage as destiny. The job is to describe what this infant is doing today—apneas, saturations, feeding—and to make space for goals of care: comfort-focused care, time-limited intensive trials, or selected interventions, decided with the family and the neonatologist, not by a hallway slogan.

Trisomy 13 adds holoprosencephaly, midline clefts, postaxial polydactyly, cutis aplasia of the scalp, heart defects, and often polycystic or otherwise abnormal kidneys. Early mortality is high. Cutis aplasia needs a protective dressing and infection watch. Midline brain and facial defects change intubation and feeding. Again, support what the family and team choose, keep the infant comfortable, and avoid both abandonment and an unexamined full-court press.

Rapid aneuploidy testing (FISH or equivalent) and a karyotype or microarray confirm what the exam already suggested. Do not withhold opioid comfort or parental holding while a laboratory runs.

Turner and Noonan

Turner syndrome (45,X) occurs in phenotypic females. Newborn clues are dorsal lymphedema of hands and feet, extra nuchal skin or a webbed neck, and left-sided heart disease—coarctation and bicuspid aortic valve. Horseshoe kidney is the classic renal finding. Fetal cystic hygroma and hydrops are antenatal versions of the same lymphatic problem. Every suspected infant needs an echo and a renal ultrasound. Gentle handling of lymphedematous skin, accurate four-limb blood pressures, and prostaglandin discussion if coarctation is ductal-dependent belong with Chapter 2–3 cardiac teaching.

Noonan syndrome can resemble Turner in the face and neck but occurs in either sex. PTPN11 and related RAS-MAPK genes are the usual molecular story; you do not need the gene name to act. Expect pulmonary stenosis, hypertrophic cardiomyopathy, lymphatic disease, cryptorchidism, feeding difficulty, and a bleeding tendency (factor deficiencies, thrombocytopenia). Echo still happens on day 1. Coagulation matters before surgery. Feeding tubes are common. Do not tell a family “it is just Turner in a boy”—that sentence is genetically wrong and clinically dangerous if you skip the pulmonary valve.

Beckwith-Wiedemann, Prader-Willi, and Angelman

Beckwith-Wiedemann syndrome is an 11p15 imprinting disorder. The NICU picture is macrosomia, macroglossia, omphalocele or umbilical hernia, ear pits or creases, visceromegaly, and hyperinsulinemic hypoglycemia. Airway first: the tongue can obstruct, especially supine. Glucose next: this is not a mild IDM dip (Chapter 13) that always resolves with one feed. High glucose infusion rates, frequent checks, and endocrine consultation (diazoxide in refractory hyperinsulinism) are in play. Later tumor surveillance (Wilms, hepatoblastoma) is a discharge-planning fact, not a warmer procedure. Do not start a Chapter 6 protein-restriction IEM protocol as the first frame for a macrosomic infant with an omphalocele and a glucose of 25 mg/dL.

Prader-Willi syndrome (paternal 15q11-q13 deletion or maternal uniparental disomy) presents as profound hypotonia, a weak cry, a poor suck, genital hypoplasia, and temperature instability. Central apnea occurs. These infants often need nasogastric or gastrostomy feeding. The later hyperphagia and obesity phenotype is not what you see in the NICU—do not wait for it to “prove” the diagnosis. Methylation analysis is the usual first genetic test. Differential includes hypoxic injury, spinal muscular atrophy, and congenital myotonic dystrophy; genetics and neurology share that list. Nursing is airway, feeding, and honest uncertainty until the test returns.

Angelman syndrome (loss of maternal UBE3A at the same 15q region) is less dramatic on day 1. You may see hypotonia and feeding difficulty without the classic later happy demeanor, ataxic gait, or seizures. Mention it because the Test Plan groups genetic conditions, and because a 15q methylation result needs correct interpretation: the same laboratory door as Prader-Willi, a different imprint. Do not diagnose Angelman from a newborn smile.

CHARGE syndrome

CHARGE (usually CHD7) is coloboma, heart defects, atresia of the choanae, retarded growth and development, genital hypoplasia, and ear anomalies. Cranial-nerve dysfunction produces swallow failure and facial palsy. Semicircular-canal hypoplasia explains later balance and hearing problems.

The neonatal emergency is bilateral choanal atresia: cyanosis with a closed mouth or during feeds, pinker with crying. Chapter 5 taught the oral airway as first aid; this section adds the syndrome around it. Do not wedge a nasal CPAP prong through an atretic choana. Do not start oral feeding until there is a patent airway. Obtain an echo—conotruncal and aortic-arch lesions are common. Involve ENT, cardiology, genetics, and feeding specialists early. Aspiration risk stays high even after choanal repair because swallow innervation may be abnormal.

Nursing cluster: feeding, heart, apnea, goals of care

Across these diagnoses the same four jobs repeat:

• Feeding: hypotonia (trisomy 21, Prader-Willi), obstruction (macroglossia, choanal atresia), or neurologic swallow failure (CHARGE, trisomy 18). Use NG or gastrostomy when the suck cannot protect the airway. Involve lactation without shaming a mother whose infant cannot transfer milk yet.
• Heart: echo for trisomy 21, 18, 13, Turner, Noonan, and CHARGE. Ductal-dependent lesions still get prostaglandin as in Chapter 2.
• Apnea: central in trisomy 18 and Prader-Willi, obstructive in Beckwith-Wiedemann and CHARGE, mixed after anesthesia. Monitor; do not treat every pause as “just prematurity” in a term dysmorphic infant.
• Goals of care: especially trisomy 13 and 18, but also severe CHARGE or hydropic Turner. Professional caring chapters later in this guide deepen advocacy and family crisis; here, know that naming the diagnosis does not by itself decide code status.

• Karyotype does not replace ABCs.
• Hyperinsulinism in Beckwith-Wiedemann is a glucose emergency, not a reason to start an IEM starvation workup first.
• Goals of care are a process with the family, not a one-line order set attached to a trisomy number.