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Rubinstein-Taybi syndrome

Rubinstein-Taybi syndrome (also known as Broad Thumb-Hallux syndrome) is a condition characterized by short stature, moderate to severe mental retardation, distinctive facial features, and broad thumbs and first toes. Other features of the disorder vary among affected individuals. more...

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Medicines

People with this condition have an increased risk of developing noncancerous and cancerous tumors, leukemia, and lymphoma. This condition is inherited in an autosomal dominant pattern and is uncommon occurring in an estimated 1 in 125,000 births.

Features of Rubinstein-Taybi syndrome

An isolated case was described in 1957 by Michail and Matsoukas. In 1963 Rubinstein and Taybi described a larger series of cases. Typical features of the disorder include:

  • Broad thumbs and broad first toes
  • Mental retardation
  • Retarded height, bone age, small head
  • Cryptorchidism in males
  • Unusual faces - eyes, nose, palate

Genetics

Mutations in the CREBBP gene cause Rubinstein-Taybi syndrome. The CREBBP gene makes a protein that helps control the activity of many other genes. The protein, called CREB binding protein, plays an important role in regulating cell growth and division and is essential for normal fetal development. If one copy of the CREBBP gene is deleted or mutated, cells make only half of the normal amount of CREB binding protein. A reduction in the amount of this protein disrupts normal development before and after birth, leading to the signs and symptoms of Rubinstein-Taybi syndrome.

Mutations in the EP300 gene are responsible for a small percentage of cases of Rubinstein-Taybi syndrome. These mutations result in the loss of one copy of the gene in each cell, which reduces the amount of p300 protein by half. Some mutations lead to the production of a very short, nonfunctional version of the p300 protein, while others prevent one copy of the gene from making any protein at all. Although researchers do not know how a reduction in the amount of p300 protein leads to the specific features of Rubinstein-Taybi syndrome, it is clear that the loss of one copy of the EP300 gene disrupts normal development.

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The Newborn Examination: Part I — Emergencies and Common Abnormalities Involving the Skin, Head, Neck, Chest, and Respiratory and Cardiovascular Systems
From American Family Physician, 1/1/02 by Mamta Fuloria

The routine newborn assessment should include an examination for size, macrocephaly or microcephaly, changes in skin color, signs of birth trauma, malformations, evidence of respiratory distress, level of arousal, posture, tone, presence of spontaneous movements, and symmetry of movements. A newborn with one anatomic malformation should be evaluated for associated anomalies. Total and direct bilirubin levels should be measured in newborns with jaundice, and a complete blood count should be obtained in those with pallor or a ruddy complexion. Neurosurgical consultation is necessary in infants with craniosynostosis accompanied by restricted brain growth or hydrocephalus, cephaloceles, or exophytic scalp nodules. Neck masses can be identified by their location and include vascular malformations, abnormal lymphatic tissue, teratomas, and dermoid cysts. Most facial nerve palsies resolve spontaneously. Conjunctivitis is relatively common in newborns. Infants with chest abnormalities may need to be evaluated for Poland's syndrome or Turner's syndrome. Murmurs in the immediate newborn period are usually innocent and represent a transition from fetal to neonatal circulation. Because cyanosis is primarily secondary to respiratory or cardiac causes, affected newborns should be evaluated expeditiously, with the involvement of a cardiologist or neonatologist. (Am Fam Physician 2002;65:61-8. Copyright[C] 2002 American Academy of Family Physicians.)

A careful examination at delivery helps the physician detect anomalies, birth injuries, and cardiorespiratory disorders that may compromise a newborn's successful adaptation to extrauterine life. A detailed examination should also be performed after the newborn has completed the transition from fetal to neonatal life. The examination may begin with an evaluation of neonatal size (Table 1). The presence of one anatomic malformation should prompt an evaluation for associated anomalies. Part I of this two-part article focuses on anomalies and disorders involving the skin, head and neck, chest, and respiratory and cardiovascular systems.

Skin

Erythema toxicum neonatorum, transient neonatal pustular melanosis, sucking blister, miliaria, and mongolian spots are among the many benign skin conditions that can occur in newborns. Total and direct bilirubin levels should be measured in newborns with jaundice, and various causes for this condition should be considered (Table 2). The American Academy of Pediatrics (1) has published guidelines on the management of hyperbilirubinemia in healthy term infants. A complete blood count should be obtained in newborns with pallor or a ruddy complexion.

The diagnosis and treatment of cutaneous vascular lesions in newborns are reviewed elsewhere.(2)

Head and Neck

Head circumference and fontanelle size can indicate a congenital disorder or head trauma (Tables 3 and 4(3)). Craniosynostosis, or premature fusion of cranial sutures, results in growth restriction perpendicular to the affected suture(s) and compensatory overgrowth in unrestricted regions(4) (Figure 1). This anomaly may suggest a genetic disorder such as Apert's syndrome or Crouzon's disease. If the synostosis is accompanied by restricted brain growth or hydrocephalus, neurosurgical intervention is necessary.

TABLE 4

Common Forms of Head Trauma in Newborns

Caput succedaneum

Commonly observed after prolonged labor

Secondary to accumulation of blood or serum above the periosteum

Clinical features: poorly demarcated soft tissue swelling that crosses suture lines; accompanying pitting edema and overlying petechiae, ecchymoses and purpura

Treatment: none needed because condition usually resolves within days

Cephalhematoma

Less common than caput succedaneum but may occur after prolonged labor and instrumentation

Secondary to rupture of blood vessels that traverse skull to periosteum

Clinical features: well-demarcated, often fluctuant swelling that does not cross suture lines; no overlying skin discoloration; possibly, skull fractures; sometimes, elevated ridge of organizing tissue

Complications: intracranial hemorrhage with resultant shock; hyperbilirubinemia

Treatment: none recommended for uncomplicated lesions, which usually reabsorb in 2 weeks to 3 months; for suspected or detected fracture, radiographs again at 4 to 6 weeks to ensure closure of linear fractures and to exclude formation of leptomeningeal cysts, which can be detected by radiography (if there is doubt, cranial computed tomographic scanning can be helpful)3; for depressed skull fractures, immediate neurosurgical consultation

Large meningoceles or encephaloceles are usually diagnosed prenatally or at birth. Smaller defects may be mistaken for cutaneous lesions such as hemangiomas or dermoid cysts. Congenital exophytic scalp nodules should always be evaluated further, because 20 to 37 percent of these lesions connect to the

underlying central nervous system.(5) Cutaneous signs of cranial dysraphism include the "hair collar sign" (darker, coarser hair encircling the scalp nodule), vascular malformations, and cutaneous dimples and sinuses. Cephaloceles and exophytic scalp nodules should be assessed by magnetic resonance imaging (MRI), and a neurosurgical consultation should be obtained.(5)

The most common neck masses are vascular malformations, abnormal lymphatic tissue, teratomas, and dermoid cysts. Neck masses can be identified based on their location (Figure 2).(6) Thyroglossal duct cysts, one of the most frequent congenital anomalies of the neck, are typically midline and inferior to the hyoid bone. Surgical consultation is required in newborns with thyroglossal duct cysts.

Clavicular fractures are the most common broken bones in newborns, especially large neonates. Of these, greenstick fractures are the most frequent and are usually asymptomatic. Newborns may present with decreased or absent movement and pain or tenderness on movement of the arm on the affected side, deformity and discoloration over the fracture site, and crepitus or irregularity along the clavicle. Treatment is directed at minimizing the newborn's pain or discomfort. If the newborn with clavicular fracture is in pain, the affected arm should be immobilized, with the arm abducted more than 60 degrees and the elbow flexed more than 90 degrees.(3)

FACE

Facial nerve paralysis is caused by compression of the nerve against the sacral promontory or by trauma resulting from the use of forceps during delivery. Paralysis is usually apparent on the first or second day of life. The nasolabial fold on the paralyzed side is obliterated, and the corner of the mouth droops; with crying, the mouth is drawn to the normal side(4) (Figure 3). With peripheral facial nerve paresis, the forehead and eyes may be affected.

Most facial nerve palsies resolve spontaneously within days, although full recovery may require weeks to months. A persistently open eye should be protected from corneal drying. Electrodiagnostic testing may be necessary if no improvement occurs within seven to 10 days; rarely, surgical intervention is needed.(3) Congenital absence or hypoplasia of the depressor anguli oris muscle may simulate facial palsy.

Erupted teeth are present in approximately one of 2,000 newborns.(7) Although natal teeth are frequently found in normal infants, they are more often present in newborns with cleft palate. They are also commonly associated with Ellis-van Creveld syndrome, Hallermann-Streiff syndrome, and pachyonychia congenita syndrome. Most erupted teeth, particularly if loose, require removal.

Isolated cleft palate differs genetically from cleft lip. Mild forms of cleft palate include submucosal clefts, pharyngeal incompetence and bifid uvula. Cleft lip, with or without cleft palate, is found in newborns with trisomy 13 syndrome, holoprosencephaly (median cleft lip), and amnion rupture sequence. Newborns with a cleft lip or palate require genetic evaluation and plastic surgery. Because of feeding difficulties, the mothers of these infants may benefit from lactation consultation and occupational therapy.

EYES

Marked lid edema often results in eversion of the upper lid when force is applied to open the eye. Examination should be postponed until the edema resolves. Subconjunctival hemorrhages, which are common after vaginal delivery, usually do not represent ocular trauma. Conjunctivitis is relatively common in newborns (Table 5).(8,9)

TABLE 5

Conjunctivitis in Newborns

Chemical conjunctivitis

Usually occurs within 24 hours of instillation of eye prophylaxis after birth

Clinical features: mild lid edema with sterile discharge from eyes

Treatment: none needed because condition usually resolves within 48 hours after birth

Gonorrheal conjunctivitis

Usually occurs within 24 to 48 hours after birth

Clinical features: profound lid edema, chemosis, intensely purulent exudates, corneal ulceration

Treatment: for proven penicillin-susceptible organisms, aqueous crystalline penicillin G, 100,000 units per kg per day IV given in four divided doses for 7 days; because of emergence of resistant strains of Neisseria gonorrhoeae, recommended therapy is ceftriaxone (Rocephin), 25 to 50 mg per kg IV or IM (not to exceed 125 mg) given once, or cefotaxime (Claforan), 100 mg per kg IV or IM given once; until discharge is eliminated, frequent eye irrigations with saline; gonorrheal treatment for the mother and her sexual partner(s)

Chlamydial conjunctivitis

Usually occurs within 7 to 14 days after birth

Clinical features: watery discharge that later becomes copious and purulent; if untreated, may result in corneal scarring and pannus formation

Treatment: orally administered erythromycin, 50 mg per kg per day in four divided doses for 2 weeks

HSV conjunctivitis

Usually occurs within 2 weeks after birth

Eyes involved in 5% to 20% of HSV-infected infants

Clinical features: infants may present with keratitis, cataracts, chorioretinitis, or optic neuritis; imperative to rule out disseminated herpes

Treatment: both topical and systemic antiviral agents, because HSV-infected neonates do not present with isolated conjunctivitis; systemic therapy--acyclovir (Zovirax), 60 mg per kg per day in three divided doses for 14 days if disease is limited to skin, eyes, and mouth; topical therapy--1% trifluridine (Viroptic) or 3% vidarabine (Vira-A); referral to subspecialist

IV = intravenous; IM = intramuscular; HSV = herpes simplex virus.

Information from Meisler DM, Beauchamp GR. Disorders of the conjunctiva. In: Nelson LB, Harley RD, eds. Harley's Pediatric ophthalmology. 4th ed. Philadelphia: Saunders, 1998:199-214, and Pickering LK, ed. 2000 Red book: report of the Committee on Infectious Diseases. 25th ed. Elk Grove Village, Ill.: American Academy of Pediatrics, 2000.

Coloboma (absence or defect of some ocular tissue) may involve the eyelid margin, as in Treacher Collins syndrome, or the iris and retina, as in the CHARGE association (syndrome of coloboma, heart disease, choanal atresia, postnatal growth retardation, genital hypoplasia and ear anomalies). Aniridia (absence of the iris) is usually bilateral and is almost always associated with poor vision and nystagmus. Newborns with aniridia or coloboma should have a formal eye examination.

The red reflex normally shows no dullness or irregularities. A white pupil (cat's eye reflex) denotes an abnormality of the lens, vitreous, or fundus. One of the most common presenting signs of a cataract is a white pupillary reflex. Congenital cataract is present in 0.4 percent of newborns. These infants should be tested for TORCH (toxoplasmosis, other viruses, rubella, cytomegaloviruses, herpes [simplex] viruses) infections. Newborns with monocular congenital or dense cataracts are at risk for developing deprivation amblyopia. Newborns with cataracts should be evaluated by an ophthalmologist.(10)

Congenital glaucoma, while uncommon, may present at birth. More often, signs of glaucoma develop during the first several weeks or months of life and include corneal cloudiness and enlargement, tearing, blepharospasm, and photophobia. Corneal edema can also occur secondary to the malpositioning of forceps during delivery. Prompt referral to an ophthalmologist is indicated.(11)

Chest

Although pectus carinatum and pectus excavatum are of concern to parents, these physical anomalies are rarely of clinical significance. Unilateral absence or hypoplasia of the pectoralis major muscle suggests the diagnosis of Poland's syndrome (sometimes called Poland's sequence). Common associated findings in this syndrome include rib defects, hypoplasia of the upper extremities, and syndactyly. Occasionally, more severe limb reduction deformities, hemivertebrae, renal anomalies, and dextrocardia may be present.

Widely spaced nipples, excessive nuchal skin, and lymphedema are findings associated with Turner's syndrome. The evaluation of newborns suspected of having this syndrome should include chromosomal analysis, echocardiography to detect cardiac lesions, and a genetic consultation.

A small thorax suggests pulmonary hypoplasia. A bell-shaped thorax is often present in newborns with neurologic abnormalities or some dwarfing syndromes.

Respiratory and Cardiovascular Systems

Newborns with choanal atresia present with cyanosis that is relieved by crying. The diagnosis is usually established by the inability to pass a catheter through the nostril(s). Unilateral choanal atresia may remain undiagnosed for years. Infants and children with this congenital anomaly may present with mucus or foul-smelling secretions from the affected nares and respiratory distress associated with upper respiratory infection.

Newborns with significant cyanosis should be evaluated expeditiously. Depending on the clinical findings, consultation with a neonatologist may be required. Respiratory disease is more likely in newborns who are tachypneic and using accessory muscles of respiration. Newborns with heart disease generally breathe normally, except for mild tachypnea or hyperpnea. The differential diagnosis and evaluation of cyanosis in infants are presented in Table 6.

The normal heart rate in newborns is 120 to 160 beats per minute. Some term newborns have a resting heart rate below 90 beats per minute. If the heart rate does not increase appropriately with stimulation, serum electrolyte levels should be checked, and an electrocardiogram should be obtained to rule out heart block.

Diminished pulses in all extremities indicate poor cardiac output or peripheral vasoconstriction. Absent or diminished femoral pulses suggest the presence of ductal-dependent cardiac lesions (e.g., coarctation of the aorta). Although hypertension is uncommon in newborns, it is rarely idiopathic. An approach to determining the cause of neonatal hypertension is presented in Figure 4.(12)

Palpation and auscultation may reveal a shift in the position of the heart from normal, as occurs in dextrocardia. In newborns, a murmur does not always signify the presence of heart disease, nor does the absence of a murmur provide reassurance of normalcy. Newborns with relatively benign lesions, such as small ventricular septal defects, often have the loudest murmurs, whereas newborns with severe heart disease may have no murmurs. The most commonly auscultated murmurs in the immediate newborn period are flow murmurs that represent a transition from fetal to neonatal circulation (e.g., tricuspid regurgitation, patent ductus arteriosus). Further evaluation is required if a murmur persists beyond several weeks in a healthy newborn or if a murmur is present in a critically ill infant.

The authors indicate that they do not have any conflicts of interest. Sources of funding: none reported.

This is part I of a two-part article on the newborn examination. Part II, "Emergencies and Common Abnormalities Involving the Abdomen, Pelvis, Extremities, Genitalia, and Spine" will appear in the next issue.

MAMTA FULORIA, M.D., is assistant professor in the Department of Pediatrics at Wake Forest University School of Medicine, Winston-Salem, N.C. Dr. Fuloria received her medical degree from King George Medical College, Lucknow, India, and completed a residency in pediatrics and a fellowship in neonatal-perinatal medicine at Wake Forest University Baptist Medical Center.

SHELLEY KREITER, M.D., is assistant professor in the Department of Pediatrics at Wake Forest University School of Medicine, where she earned a medical degree and completed a residency in pediatrics. Dr. Kreiter is currently completing a master's degree in epidemiology at Wake Forest University.

Address correspondence to Mamta Fuloria, M.D., Department of Pediatrics, Wake Forest University School of Medicine, Medical Center Blvd., Winston-Salem, NC 27157 (mfuloria@wfubmc.edu). Reprints are not available from the authors.

REFERENCES

(1.) Practice parameter: management of hyperbilirubinemia in the healthy term newborn. American Academy of Pediatrics. Provisional Committee for Quality Improvement and Subcommittee on Hyperbilirubinemia. Pediatrics 1994;94(4 pt 1):558-65.

(2.) Wirth FA, Lowitt MH. Diagnosis and treatment of cutaneous vascular lesions. Am Fam Physician 1998;57:765-73.

(3.) Mangurten HH. Birth injuries. In: Fanaroff AA, Martin RJ, eds. Neonatal-perinatal medicine: diseases of the fetus and infant. 6th ed. St. Louis: Mosby-Year Book, 1997:425-54.

(4.) Fletcher MA. Physical diagnosis in neonatology. Philadelphia: Lippincott-Raven, 1998:173-235.

(5.) Drolet BA. Cutaneous signs of neural tube dysraphism. Pediatr Clin North Am 2000;47:813-23.

(6.) May M. Neck masses in children: diagnosis and treatment. Pediatr Ann 1976;5:518-35.

(7.) Nazif MM, Davis H, McKibben DH, Ready MA. Oral disorders. In: Zitelli BJ, Davis HW, eds. Atlas of pediatric physical diagnosis. 2d ed. Philadelphia: Mosby-Wolfe, 1996:20.1-20.21.

(8.) Meisler DM, Beauchamp GR. Disorders of the conjunctiva. In: Nelson LB, Harley RD, eds. Harley's Pediatric ophthalmology. 4th ed. Philadelphia: Saunders, 1998:199-214.

(9.) Pickering LK, ed. 2000 Red book: report of the Committee on Infectious Diseases. 25th ed. Elk Grove Village, Ill.: American Academy of Pediatrics, 2000.

(10.) Potter WS. Pediatric cataracts. Pediatr Clin North Am 1993;40:841-53.

(11.) Wagner RS. Glaucoma in children. Pediatr Clin North Am 1993;40:855-67.

(12.) Bada-Ellzey HS. Hypertension. In: Korones SB, Bada-Ellzey HS, eds. Neonatal decision making. St. Louis: Mosby-Year Book, 1993:152-3.

COPYRIGHT 2002 American Academy of Family Physicians
COPYRIGHT 2002 Gale Group

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