Syndrome de Nager associé à une tétralogie de Fallot : une association fréquente ?

Abstract

Nager syndrome belongs to a heterogeneous group of disorders involving abnormal development of the extremities, face, and jaw: acrofacial dysostosis (AFD). Fewer than 100 cases of Nager syndrome have been reported to date. Recently, mutations in the 1q21.2 region of the SF3B4 gene (splicing factor 3B subunit 4), which encodes a spliceosomal protein (SAP49) involved in the assembly of the spliceosomal complex U2SNP, have been demonstrated in patients with Nager syndrome. We report the case of a child who had a characteristic association (Pierre Robin sequence, bilateral and symmetrical malar hypoplasia, absent thumbs) clinically diagnosed as Nager syndrome. This child also presented tetralogy of Fallot. This combination is unusual; only two other cases have been described. The karyotype and the CGH-array were normal. After the description in 2012 of several mutations in the SF3B4 gene (1q21.2) in Nager syndrome, a genetic search for our patient revealed the mutation c.1229delC. In 2013, other authors showed the presence of these same mutations in the majority of their patients diagnosed as Nager syndrome. The haploinsufficiency of the SF3B4 region seems to be the major cause of Nager syndrome.