Novel FOXL2 mutations in two Chinese families with blepharophimosis-ptosis-epicanthus inversus syndrome

Abstract

Background: Blepharophimosis-ptosis-epicanthus inversus syndrome (BPES) is a rare autosomal dominant disease. Mutations in the forkhead box L2 (FOXL2) gene cause two types of BPES distinguished by the presence (type I) and absence (type II) of premature ovarian failure (POF). The purpose of this study was to identify possible mutations in FOXL2 in two Chinese families with BPES.

Methods: Two large autosomal dominant Chinese BPES families were enrolled in this study. Genomic DNA was obtained from the leukocytes in peripheral venous blood. Four overlapping sets of primers were used to amplify the entire coding region and nearby intron sequences of the FOXL2 gene for mutations detection using polymerase chain reaction (PCR) and sequencing analyses. The sequencing results were analyzed using DNAstar software.

Results: All patients of the two families demonstrated typical features of BPES type II, including small palpebral fissures, ptosis, telecanthus, and epicanthus inversus without female infertility (POF). A novel FOXL2 heterozygous indel mutation c.675_690delinsT, including a 16-bp deletion and a 1-bp(T) insertion (p.Ala226_Ala230del), which would result in deletion of 5 alanine residues of a poly-alanine (poly-Ala) tract in the protein, was identified in all affected members of family A. A novel heterozygous missense mutation (c.223C > T, p.Leu75Phe) was identified in family B.

Conclusions: Two novel FOXL2 mutations were identified in Chinese families with BPES. Our results expand the spectrum of FOXL2 mutations and provide additional structure-function insights into the FOXL2 protein.

Fig. 1

Pedigrees of two Chinese families

Fig. 2

The PCR products amplified by primer 4 in the Family a. Patients’ PCR products revealed two fragments of 304 and 289 bp using 6 % agarose gel electrophoresis. Normal individual contained a single fragment of 304 bp. The right lane is DNA marker (100bp)

Fig. 3

Pictures representing the ocular defects of BPES patients from two Chinese families. Patients experience a combination of congenital eyelid anomalies: small palpebral fissures, ptosis, telecanthus, and epicanthus inversus. The left is Family (a) and the right is Family (b)

Fig. 4

Sequencing results of the two novel mutations in FOXL2 (the heterozygous mutation c.675_690delinsT in family a and the missense mutation (c.223C > T) in family b). The mutant alleles identified in the present study are compared with the normal alleles. The red marks indicate the position of mutations