Birth defects: Approach to evaluation
- Carlos A Bacino, MD, FACMG
Carlos A Bacino, MD, FACMG
- Professor of Molecular and Human Genetics
- Baylor College of Medicine
- Section Editors
- Helen V Firth, DM, FRCP, DCH
Helen V Firth, DM, FRCP, DCH
- Section Editor — Genetics
- Consultant Clinical Geneticist
- Addenbrooke's Hospital, Cambridge, UK
- Louise Wilkins-Haug, MD, PhD
Louise Wilkins-Haug, MD, PhD
- Section Editor — Prenatal Diagnosis and Genetics
- Professor of Obstetrics, Gynecology, and Reproductive Biology
- Harvard Medical School
A birth defect is any structural anomaly present at birth that may interfere with function depending upon the organ or structure involved (eg, meningomyelocele and ambulation, or cleft palate and feeding and speech). These defects can be caused by genetic abnormalities and/or environmental exposures, although the underlying etiology is often unknown. Birth defects can be isolated or present in a characteristic combination or pattern that may affect one or more organ systems.
Evaluation of a child with a birth defect includes a comprehensive history and physical examination. This is followed by further testing, as indicated. A general approach to evaluation is presented here. More detailed descriptions are included in the topic reviews of specific disorders. The types, patterns, and causes of birth defects are also discussed separately. (See "Birth defects: Epidemiology, types, and patterns" and "Birth defects: Causes".)
REFERRAL FOR INITIAL EVALUATION
Referral to a genetic specialist is suggested for any child that presents with a single major birth defect or a combination of multiple birth defects, whether those are major or minor, since the risk for having a syndrome increases with the number of defects and some syndromes have a genetic etiology. In addition, any family history of a specific birth defect(s) or history of miscarriages and/or stillbirths should prompt referral to a geneticist. Other referrals may include plastic surgery for limb anomalies (polydactyly, syndactyly) or for craniosynostoses, orthopedics for clubfoot deformities, ophthalmology for microphthalmia, and neurology for microcephaly.
The prenatal history may uncover specific exposures and etiologic factors. This should include medical and obstetric history, such as the duration of gestation, prenatal care, and maternal exposures (eg, alcohol, prescribed or illicit drugs, cigarettes, fevers, illnesses, chemicals, radiation). A history of stillbirths and miscarriages could be related to a balanced chromosomal rearrangement in one of the parents. Results of noninvasive and invasive prenatal testing, including ultrasound examinations, should be obtained. (See "Assessment of the newborn infant", section on 'History' and "Birth defects: Causes" and "Routine prenatal ultrasonography as a screening tool".)
A complete family history and pedigree (four generations, if possible) should be obtained to help uncover genetic causes. The age of the parents is important because the incidence of chromosome aneuploidies is increased in older mothers and de novo autosomal dominant mutations (eg, achondroplasia, neurofibromatosis type 1) are more commonly seen with older parents, with the effect being more marked for advanced paternal age. The parents should be asked about consanguinity, which increases the incidence of autosomal recessive disorders. (See "Congenital cytogenetic abnormalities", section on 'Numeric abnormalities' and "Achondroplasia" and "Neurofibromatosis type 1 (NF1): Pathogenesis, clinical features, and diagnosis".)
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