Congenital Malformations, Inborn Errors of Metabolism, and Chromosomal Disorders

Comprehensive vocabulary flashcards covering congenital malformations of the CNS, cardiovascular, GI, GU, and skeletal systems, along with inborn errors of metabolism and chromosomal disorders in the at-risk newborn.

Phenylketonuria (PKU)

An autosomal recessive inborn error of metabolism where the infant lacks the hepatic enzyme needed to convert the essential amino acid phenylalanine into tyrosine, leading to blood phenylalanine accumulating to as much as $20$ times normal levels and causing permanent brain damage and progressive mental disability if untreated.

Guthrie Inhibition Assay Test

A mandatory neonatal blood screening test performed via heel prick within $2\text{--}3\text{ days}$ of life (most reliable after the ingestion of protein) to detect elevated blood levels of phenylalanine.

Lofenalac

A specialized commercial infant formula low in phenylalanine that serves as the dietary mainstay for infants diagnosed with phenylketonuria.

Galactosemia

An autosomal recessive metabolic defect characterized by the absence of the enzyme required to convert galactose into glucose, presenting with vomiting, diarrhea, jaundice, cataracts, and intellectual disability after milk feedings.

Congenital Hypothyroidism

A condition resulting from the absence of a thyroid gland or inability to synthesize thyroid hormones, typically manifesting by $6\text{ weeks}$ of life with a depressed nasal bridge, large tongue, puffy eyes, hoarse cry, dry cold skin, chronic constipation, and abdominal enlargement.

Maple Syrup Urine Disease (MSUD)

A rapidly progressive, autosomal recessive defect in the metabolism of branched-chain amino acids manifesting in the first week of life with feeding difficulties, seizures, spasticity, opisthotonos, and a characteristic maple syrup odor in the urine; requires dietary intervention within $12\text{ days}$ of birth.

Cystic Fibrosis

An autosomal recessive condition in which a mutated gene impairs chloride and sodium transport across epithelial surfaces, causing exocrine glands to produce thick mucus that obstructs the respiratory tract, pancreatic ducts, and gastrointestinal system (often presenting in $10\text{--}20\%$ of newborns as meconium ileus).

Spina Bifida Occulta

A defect in the vertebral neural arch without soft tissue involvement or protrusion of neural elements, commonly asymptomatic and characterized only by an overlying skin dimple or tuft of hair in the lumbosacral region.

Spina Bifida with Meningocele

A neural tube defect where the meninges and cerebrospinal fluid protrude through a bony defect in the spine to form an external cystic sac without the involvement of spinal cord tissue or nerve roots.

Spina Bifida with Myelomeningocele

The most severe form of spina bifida, characterized by an external protrusion of the meninges and spinal cord with nerve roots embedded in the cyst wall, resulting in motor sensory deficits or complete flaccid paralysis below the lesion along with neurogenic bowel and bladder impairment.

Maternal Serum Alpha-Fetoprotein (MSAFP)

A prenatal maternal serum or amniotic fluid screening test ideally obtained between $13\text{ and }15\text{ weeks'}$ gestation, where elevated levels indicate the probability of fetal neural tube defects or multiple gestations.

Noncommunicating Hydrocephalus

A form of hydrocephalus characterized by an anatomical obstruction within the ventricular system (commonly a stenosis in the aqueduct of Sylvius) that prevents cerebrospinal fluid from flowing into the spinal subarachnoid space.

Communicating Hydrocephalus

A condition in which cerebrospinal fluid flows freely through the ventricular system but is improperly or defectively absorbed into the venous system through the arachnoid villi, resulting in elevated intracranial pressure.

Setting Sun Sign

A clinical ocular sign seen in advanced infant hydrocephalus and increased intracranial pressure where the eyes are displaced downward, revealing the white sclera visible above the iris.

Cushing's Triad

A classic late sign of significantly elevated intracranial pressure in infants consisting of increased blood pressure, bradycardia, and widening pulse pressure.

Ventriculoperitoneal (VP) Shunting

A surgical intervention for hydrocephalus in which a radiopaque silicone catheter with a pressure-regulating valve is routed subcutaneously to drain excess cerebrospinal fluid from a lateral cerebral ventricle into the peritoneal cavity.

Cyanotic Heart Disease

Cardiovascular malformations that allow deoxygenated blood from the right side of the heart to shunt directly into the left side of the heart (right-to-left shunting), producing peripheral arterial oxygen saturations of $85\%$ or less.

Ventricular Septal Defect (VSD)

The most common congenital intracardiac anomaly, consisting of an abnormal opening in the ventricular septum that permits left-to-right shunting without cyanosis unless pulmonary vascular resistance produces pulmonary hypertension.

Atrial Septal Defect (ASD)

An abnormal opening between the right and left atria (commonly caused by an incompetent foramen ovale) that allows left-to-right shunting of blood without producing cyanosis.

Patent Ductus Arteriosus (PDA)

Failure of the fetal vessel connecting the left main pulmonary artery to the descending aorta to obliterate after birth, producing left-to-right shunting, a classic machine-like murmur, a wide pulse pressure, and bounding peripheral pulses.

Indomethacin

A prostaglandin inhibitor medication administered to premature newborns to promote pharmacologic closure of a patent ductus arteriosus.

Coarctation of the Aorta

A localized narrowing or constriction of the aortic arch or descending aorta near the ligamentum arteriosum, causing left ventricular strain, upper extremity hypertension, weak or absent femoral pulses, and rib notching from collateral arterial flow.

Tetralogy of Fallot

The most common cyanotic congenital heart defect, consisting of four concurrent anomalies: pulmonary stenosis, ventricular septal defect, overriding aorta, and right ventricular hypertrophy.

Tet Spells (Anoxic Spells)

Sudden paroxysmal hypercyanotic episodes in infants with Tetralogy of Fallot characterized by severe restlessness, gasping respirations, deepening cyanosis, and possible loss of consciousness; frequently relieved by placing the child in a knee-chest or squatting position.

Transposition of the Great Arteries (TGA)

A congenital cardiovascular defect where the aorta originates from the right ventricle and the pulmonary artery originates from the left ventricle, creating two parallel, unmixed circuits that produce profound cyanosis at birth.

Blalock-Taussig Procedure

A palliative surgical procedure for infants with Tetralogy of Fallot who cannot tolerate immediate total correction, involving an end-to-end anastomosis of a systemic vessel (usually the subclavian artery) to a pulmonary artery.

Cardiac Catheterization

An invasive procedure where a radiopaque catheter is advanced into the heart under fluoroscopy; postoperative care mandates keeping the cannulated extremity straight and flat in bed for $4\text{--}8\text{ hours}$ (or up to $6\text{ hours}$) while monitoring distal pulses, perfusion, and insertion site bleeding.

Cleft Lip

A congenital fissure in the upper lip caused by the failure of the maxillary and median nasal processes to fuse between the fifth and eighth weeks of intrauterine life, commonly repaired within the first $1\text{--}2\text{ months}$ of life.

Cleft Palate

A congenital opening in the roof of the mouth resulting from the failure of embryonic palatal shelves to meet and fuse in the midline between the $10\text{th}\text{ and }12\text{th}\text{ weeks}$ of gestation, optimally repaired between $6\text{ months and }5\text{ years}$ of age (or $6\text{--}12\text{ months}$) to facilitate normal speech development.

Logan Bow

A curved wire appliance taped to an infant's cheeks across the upper lip to protect and reduce mechanical tension on the surgical suture line after a cleft lip repair.

Esophageal Atresia (EA)

A congenital malformation where the proximal esophagus terminates in a blind pouch rather than connecting to the stomach, presenting with excessive frothing, drooling, coughing, choking, and cyanosis.

Tracheoesophageal Fistula (TEF)

An abnormal communication between the trachea and the esophagus (most commonly connecting the distal esophagus to the trachea), allowing gastric secretions to reflux into the respiratory tree and predisposing the infant to aspiration pneumonia.

Imperforate Anus

A congenital gastrointestinal anomaly where the normal anal orifice is absent due to persistent embryonic membrane blockage between the rectum and anus, presumptively identified when a newborn fails to pass meconium within $24\text{ hours}$ of birth.

Omphalocele

A congenital abdominal wall defect in which abdominal contents (bowel loops and sometimes the liver) herniate through the base of the umbilical cord inside a transparent sac covered by peritoneal membrane.

Umbilical Hernia

A common, typically benign protrusion of omentum and intestine through an incompletely closed umbilical ring that generally resolves spontaneously without surgery before $3\text{ years}$ of age.

Congenital Diaphragmatic Hernia

A life-threatening defect characterized by herniation of abdominal viscera into the thoracic cavity through an opening in the diaphragm, displacing the heart and causing pulmonary hypoplasia, severe dyspnea, and cyanosis on the first day of life.

Hypospadias

A congenital male genitourinary anomaly where the urethral meatus opens on the ventral (underside) surface of the penis rather than at the glans tip; neonatal circumcision is deferred to preserve foreskin tissue for surgical reconstruction.

Epispadias

A congenital defect in which the urinary meatus terminates on the dorsal (upper) surface of the penis, frequently occurring in association with bladder exstrophy.

Exstrophy of the Bladder

A severe urinary tract malformation characterized by the failure of the lower abdominal wall and anterior bladder wall to close, leaving the sensitive, mucosal surface of the posterior bladder wall exposed on the lower abdomen.

Ambiguous Genitalia

Incomplete or atypical development of the external genitalia at birth that precludes visual determination of chromosomal sex, necessitating diagnostic cytogenetic and endocrine evaluation before surgical reconstruction and sex assignment.

Congenital Talipes Equinovarus

The most common congenital foot deformity (clubfoot) involving fixed inversion, plantar flexion (equinus), and forefoot adduction, managed primarily with serial manipulation and casting initiated in the neonatal period.

Denis Browne Splint

An orthopedic device consisting of footplates connected by an adjustable metal bar, used after serial casting for clubfoot to maintain corrective outward rotation and abduction.

Developmental Dysplasia of the Hip (DDH)

A congenital skeletal disorder where abnormal acetabular development permits upward and backward dislocation of the femoral head, characterized clinically by asymmetric gluteal skin folds, limited hip abduction ($< 45^\circ$), and apparent shortening of the femur.

Ortolani and Barlow Maneuvers

Physical assessment techniques used during neonatal hip examination to detect subluxation or dislocation, where a positive Ortolani test reduces a dislocated hip back into the acetabulum with a palpable 'clunk' or click upon abduction.

Pavlik Harness

A dynamic orthopedic harness consisting of chest straps, shoulder straps, and foot stirrups that maintains bilateral hips in flexion and abduction to stabilize the femoral head in developmental dysplasia of the hip.

Hip Spica Cast

An orthopedic cast applied from the waist downward encasing one or both legs with hips maintained in wide abduction and froglike flexion, used after traction or open surgical reduction for developmental hip dysplasia.

Spastic Cerebral Palsy

The most common clinical subtype of cerebral palsy, characterized by hyperactive stretch reflexes, clonus, persistent primitive reflexes, contractures of extensor muscles, and scissoring of the lower limbs due to severe hip adduction.

Athetoid Cerebral Palsy

A subtype of cerebral palsy characterized by involuntary, slow, writhing muscle contractions affecting voluntary movement, associated with facial grimacing, drooling, dysarthria, and sensorineural hearing loss, typically alongside normal intelligence.

Ataxic Cerebral Palsy

The least common subtype of cerebral palsy, caused by damage to balance and kinesthetic pathways, manifesting with uncoordinated movements, poor equilibrium, and an awkward, wide-based gait.

Down Syndrome (Trisomy 21)

The most common chromosomal nondisjunction disorder, involving an extra copy of chromosome 21 and characterized by brachycephaly, upward slanting palpebral fissures with epicanthal folds, depressed nasal bridge, protruding tongue, generalized hypotonia, a single transverse palmar crease, and congenital heart defects.

Turner Syndrome

A sex chromosome monosomy occurring exclusively in females ($45, \text{XO}$) resulting from the partial or complete absence of an X chromosome, manifesting with short stature, a webbed neck, low posterior hairline, broad chest, congenital heart defects, and ovarian dysgenesis with lack of secondary sex characteristics.

Klinefelter Syndrome

A sex chromosome nondisjunction disorder occurring in males who have an extra X chromosome ($47, \text{XXY}$), presenting at puberty with eunuchoid proportions, long extremities, sparse facial hair, gynecomastia, and small sterile testes requiring testosterone replacement therapy.

Small for Gestational Age (SGA)

A designation applied to any neonate whose birth weight, crown-to-heel length, or head circumference falls below the $10\text{th}\text{ percentile}$ for gestational age as a result of intrauterine growth restriction.