title: Epidemiology of isolated preaxial polydactyly type I: data from the Polish Registry of Congenital Malformations (PRCM).
abstract: BACKGROUND
  Polydactyly represents a heterogeneous group of congenital hand and foot anomalies with variable clinical features and diverse etiology. Preaxial polydactyly type I (PPD1) is the most frequent form of preaxial polydactyly. The etiology of sporadic PPD1 remains largely unknown and the relative contribution of genetic and environmental factors is not clearly defined. The primary goals of this study are twofold: (1) to examine the epidemiology and clinical features of sporadic PPD1 in comparison to a healthy control group, and (2) to contrast the characteristics of sporadic PPD1 with familial forms of isolated polydactyly.
  
  
  METHODS
  Among 2,530,349 live births registered in the Polish Registry of Congenital Malformations (PRCM), we identified 459 children with isolated sporadic PPD1 and 353 children with familial polydactyly, including 57 children with familial PPD1.
  
  
  RESULTS
  In comparison with the matched group of 303 controls, sporadic PPD1 cases had significantly lower birth order (P = 0.01) and birthweight (P < 0.0001). Similarly, when compared to familial cases of polydactyly, lower birth order (P = 0.047) and lower birthweight (P < 0.0001) were characteristic of sporadic PPD1 cases. Moreover, our analyses suggested several additional risk factors for sporadic PPD1, including lower paternal education levels (P = 0.01), upper respiratory tract infections during the first trimester of pregnancy (P = 0.049), and maternal history of epilepsy (P = 0.01).
  
  
  CONCLUSIONS
  In summary, our study provides support to the hypothesis that non-genetic factors play an important role in the etiology of non-familiar PPD1.
authors: Chair and Department of Medical Genetics, Poznan University of Medical Sciences, Poznan, Poland. akiryluk@ump.edu.pl
authors: Anna
authors: A
authors: Materna-Kiryluk
authors: Aleksander
authors: A
authors: Jamsheer
authors: Katarzyna
authors: K
authors: Wisniewska
authors: Barbara
authors: B
authors: Wieckowska
authors: Janusz
authors: J
authors: Limon
authors: Maria
authors: M
authors: Borszewska-Kornacka
authors: Henryka
authors: H
authors: Sawulicka-Oleszczuk
authors: Ewa
authors: E
authors: Szwalkiewicz-Warowicka
authors: Anna
authors: A
authors: Latos-Bielenska
mesh_terms: D001722:Birth Order; D016022:Case-Control Studies; D005260:Female; D006801:Humans; D015994:Incidence; D007230:Infant, Low Birth Weight; D007231:Infant, Newborn; D016015:Logistic Models; D008297:Male; D011044:Poland / Q000453:epidemiology; D017689:Polydactyly / Q000175:diagnosis / Q000453:epidemiology* / Q000209:etiology; D012042:Registries; D012307:Risk Factors; D013933:Thumb / Q000002:abnormalities*