Fetal Polydactyly

Abstract

A Study of 24 Cases Ascertained by Prenatal Sonographyongenital malformations of the limbs are among the most frequent congenital anomalies in humans. They are clinically and genetically heterogeneous and preferentially affect the distal parts of limbs: the hands and feet. 1,2 The presence of an abnormal number of digits is the most frequent limb anomaly and is a consequence of a disturbance in the genetic program of embryonic limb development. Polydactyly implies the occurrence of supernumerary digits and toes, whereas oligodactyly indicates fewer than 5 digits. An anomaly in the number of digits can appear as an isolated condition or be part of a syndrome including additional malformations, cognitive impairment, or both.Improvements in sonographic techniques and improved training of specialists in fetal sonography have increased early detection of structural defects, including polydactyly, in the first trimester of pregnancy. 3,4 Counseling of parents in a case of fetal polydactyly is challenging because there is a potential risk of occurrence in a syndromic context, including a prognosis of developmental disability for the child. It is sometimes difficult to draw the line between isolated and syndromic polydactyly. Therefore, it is extremely important to obtain information as completely as possible on the family history, familial occurrence of polydactyly, detailed clinical information on the fetus by sonography, and genetic testing by invasive diagnosis if necessary, especially for chromosomal anomalies. We describe our experience with 24 pregnancies in our tertiary antenatal center, which handles routine examinations as well as high-risk pregnancies and is a referral center for genetic sonography. CASE SERIESRecords of 24 pregnancies with fetal polydactyly were reviewed for the type of polydactyly, family history, associated sonographic findings, genetic testing, and postnatal/postmortem examination findings. The importance of fetal polydactyly can be mainly elucidated by the family history and absent or associated anomalies on a specialized malformation scan. Fetal karyotyping diagnoses frequent chromosomal anomalies in about half of cases with additional malformations, and array comparative genomic hybridization may be a future means of detecting cryptic chromosomal aberrations. Syndromic disorders of monogenic origin demand a careful interdisciplinary clinical assessment for establishing a clinical diagnosis and prognosis for the outcome of the child.