FOXL2 gene mutations cause blepharophimosis-ptosis-epicanthus inversus syndrome (BPES) and may be associated with premature ovarian insufficiency (POI).
The in vitro experiments provide further insights into the molecular mechanism by which the two new variants mediate disease pathogenesis and may contribute to elucidating the genotype-phenotype correlation between the two novel FOXL2 mutations and POI.
Blepharophimosis-ptosis-epicanthus inversus syndrome (BPES) is a rare autosomal dominant disease caused by FOXL2 gene mutations, and it is clinically characterized by an eyelid malformation associated (type I) or not (type II) with premature ovarian failure (POF).
In women, over 120 different germline mutations in the FOXL2 gene have been shown to cause blepharophimosis/ptosis/epicantus inversus syndrome associated with or without primary ovarian insufficiency.
Mutations in some master regulators of the development, maturation, and maintenance of ovarian follicles such as BMP15, FSHR, FOXL2, and GDF9 have been suggested as etiological factors in the development of POI.
Germline mutations of the fork-head transcriptional factor forkhead box L2 (FOXL2) predispose embryos to autosomal-dominant blepharophimosis-ptosis-epicanthus inversus syndrome with primary ovarian insufficiency in female patients, but the mechanisms of FOXL2 in ovarian follicular development remain elusive.
Forkhead box L2 (FOXL2) is a transcription factor, which is involved in blepharophimosis, ptosis, and epicanthus in versus syndrome (BPES), premature ovarian failure (POF), as well as almost all stages of ovarian development and function.
Blepharophimosis syndrome (BPES) is an autosomal dominant genetic condition resulting from heterozygous mutations in the FOXL2 gene and clinically characterized by an eyelid malformation associated (type I) or not (type II) with premature ovarian failure.
Mutations in FOXL2 are known to cause autosomal dominant blepharophimosis-ptosis-epicanthus inversus syndrome (BPES), variably associated with premature ovarian failure.
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).
Haploinsufficiency of the FOXL2 transcription factor in humans causes Blepharophimosis/Ptosis/Epicanthus Inversus syndrome (BPES), characterized by eyelid anomalies and premature ovarian failure.
A novel insertion in the forkhead transcription factor 2 (FOXL2) was identified in a Chilean patient with blepharophimosis, ptosis, and epicanthus inversus syndrome associated with premature ovarian failure (BPES type I).
FOXL2 is a transcription factor that is essential for ovarian function and maintenance, the germline mutations of which give rise to the blepharophimosis ptosis epicanthus inversus syndrome (BPES), often associated with premature ovarian failure.
Blepharophimosis syndrome is a recognizable ocular phenotype (blepharophimosis, telecanthus, ptosis, and epicanthus inversus) caused by heterozygous (dominant) intragenic mutation in FOXL2 (chromosome 3q23), which can also cause premature ovarian failure.
Mutant Forkhead L2 (FOXL2) proteins associated with premature ovarian failure (POF) dimerize with wild-type FOXL2, leading to altered regulation of genes associated with granulosa cell differentiation.
We show that: (i) allelic reduction of Dlx5 and Dlx6 in the mouse results in a POI-like phenotype, characterized by reduced fertility and early follicular exhaustion; (ii) in granulosa cell lines, a reciprocal regulation exists between Dlx5 and Foxl2; (iii) in the mouse ovary, allelic reduction of Dlx5/6 results in the upregulation of Foxl2.
Here, we report a novel missense mutation in the forkhead domain of the FOXL2 gene (c.340A > G, NM_023067) resulted in the replacement of lysine by glutamic acid at amino acid position 114 of the FOXL2 protein (p.K114E, NP_075555) that was identified in a Chinese family with BPES type I, members of which displayed clinical symptoms such as shortened palpebral fissures, drooping eyelids, a vertical skin fold arising from the lower eyelid, and premature ovarian failure (POF) in affected females.
Some mutations in FOXL2 result in premature ovarian failure accompanied by blepharophimosis, ptosis, epicanthus inversus syndrome type I disease, and FOXL2-null mice exhibit developmental defects in granulosa cells.
The results came back with no novel mutations but one common 30 bp duplication within FOXL2 polyalanine tract in the abovementioned POF plus BPES patient, suggesting mutations in FOXL2 gene was not common among Chinese patients with POF.
Histological and immunohistological studies were conducted on ovarian biopsies from two women with POF carrying a FOXL2 mutation resulting in putative polyalanine expansions of the protein.
This report demonstrates a previously undescribed de novo mutation in the FOXL2 gene-a thymidine deletion, c.627delT (g.864delT)-in a woman with a sporadic case of BPES and POF.
FOXL2 is a forkhead transcription factor, essential for ovarian function, whose mutations are responsible for the blepharophimosis syndrome, characterized by craniofacial defects, often associated with premature ovarian failure.
Our data provide evidence in favour of the implication of FOXL2 variants in non-syndromic POF and confirm the regulatory interaction between FOXL2 and OSR2 whose perturbation might contribute to the palpebral abnormalities observed in BPES patients.