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Limb deficiencies in newborn infants
C K McGuirk1, M N Westgate, L B Holmes
1Genetics and Teratology Unit, Pediatric Service, Massachusetts General Hospital, Boston, Massachusetts, USA. cmcguirk@partners.org
Insights
Limb reduction defects affect 0.69/1000 infants. Vascular disruption is the most common cause, accounting for 35% of cases, highlighting the need for surveillance programs in evaluating infant limb deficiencies.
Area of Science:
- Medical surveillance
- Birth defects epidemiology
- Congenital abnormalities
Background:
- Limb reduction defects (LRDs) are congenital abnormalities requiring accurate prevalence data.
- Establishing baseline rates is crucial for evaluating infants exposed to potential teratogens, particularly those causing vascular disruption.
- Understanding the etiology of LRDs aids in risk assessment and prevention strategies.
Purpose of the Study:
- To determine the prevalence of all types of limb reduction defects.
- To specifically ascertain the prevalence of LRDs potentially caused by vascular disruption.
- To provide a baseline for evaluating infants exposed in utero to vascular disrupting teratogens.
Main Methods:
- A hospital-based Active Malformations Surveillance Program identified LRDs in liveborn, stillborn, and electively terminated infants.
- Data collection spanned 1972–1974 and 1979–1994, with an extended search to ensure comprehensive ascertainment.
- Limb defects were classified by anatomical location, affected digits, and apparent cause.
Main Results:
- The overall prevalence of limb deficiency was 0.69 per 1000 births.
- Vascular disruption was identified as the apparent cause in 35% of LRD cases.
- The prevalence of LRDs attributed to presumed vascular disruption was 0.22 per 1000 births.
Conclusions:
- Hospital-based surveillance, including elective terminations, effectively establishes LRD prevalence.
- Clinical findings provide more accurate etiological classification of LRDs than ICD codes alone.
- The study provides essential baseline data on LRDs, particularly those linked to vascular disruption.
Objective:
The prevalence rate of all types of limb reduction defects in general and those that potentially are caused by vascular disruption in particular is needed to provide a baseline for the evaluation of infants who are exposed in utero to teratogens that cause vascular disruption. The objective of this study was to determine this prevalence rate.
Methods:
All infants with any limb deficiency among 161 252 liveborn and stillborn infants and elective terminations were identified in a hospital-based Active Malformations Surveillance Program in Boston in the years 1972 to 1974 and 1979 to 1994. An extensive search was made to identify infants who were missed by the Surveillance Program; an additional 8 infants (7.3% of total) were identified. The limb reduction defects were classified in 3 ways: 1) by the anatomic location of the defect, that is longitudinal, terminal, intercalary, etc; 2) for infants with absence/hypoplasia of fingers or toes, a tabulation of which digit or digits were affected; and 3) by apparent cause.
Results:
The prevalence rate for all types of limb deficiency was 0.69/1000. The apparent causes included single mutant genes, familial occurrence, and known syndromes (24%); chromosome abnormalities (6%); teratogens (4%); vascular disruption (35%); and unknown cause (32%).
Conclusions:
A hospital-based surveillance program can be used to establish the prevalence of limb reduction defects, if ascertainment is extended to include elective terminations for fetal abnormalities. An apparent cause can be established for most limb defects when the clinical findings are used rather than reliance only on the International Classification of Diseases, Ninth Revision, codes of the discharge diagnoses. The prevalence rate of limb reduction defects as a result of presumed vascular disruption was 0.22/1000.
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