BPES, short for blepharophimosis-ptosis-epicanthus inversus syndrome, is a rare genetic condition that affects the eyelids and, in roughly half of cases, also causes premature ovarian failure in women. It is defined by four overlapping eyelid abnormalities present from birth: narrowed eye openings, drooping upper lids, an inward skin fold near the inner corners of the eyes, and increased distance between the inner corners themselves. All four features stem from mutations in a single gene called FOXL2 on chromosome 3, and the condition follows an autosomal dominant inheritance pattern, meaning one altered copy of the gene is enough to cause it.
The Four Eyelid Features
The name of the syndrome is essentially a list of what it looks like. Blepharophimosis refers to a horizontal narrowing of the palpebral fissure, the opening between the upper and lower lids. Ptosis is a drooping of the upper eyelid, which in BPES tends to be moderate to severe and affects both eyes. Epicanthus inversus is a skin fold that arises from the lower eyelid and sweeps upward toward the inner corner of the eye, the reverse of the more common epicanthal fold. Telecanthus means the inner corners of the eyes are spaced farther apart than usual, though the eyes themselves may sit in normal positions within the skull. When all four features appear together, clinicians typically recognize the pattern on physical examination alone.1PubMed Central. Blepharophimosis Ptosis Epicanthus Inversus Syndrome (BPES) Type 1 in an Indian Family
For many parents, the first concern is functional rather than cosmetic. The narrowed lid openings and drooping lids can obstruct the visual axis, especially in young children whose visual systems are still developing. In one surgical series, about 31% of children who underwent correction before age five already had amblyopia, sometimes called “lazy eye,” caused by the chronically obstructed field of vision.2PubMed Central. One-stage correction for blepharophimosis syndrome That statistic underscores why early evaluation matters: untreated ptosis during the critical window of visual development can permanently reduce visual acuity even after the lids are eventually corrected.
Type I Versus Type II
BPES is divided into two types based on whether it affects fertility. Both types produce the same set of eyelid findings, and both are caused by mutations in the same gene. The difference is what happens to the ovaries. In Type I, women develop premature ovarian failure, meaning their ovaries stop functioning well before the typical age of menopause, leading to infertility or severely reduced fertility. In Type II, ovarian function is preserved and women can conceive without assistance.3Journal of Reproduction and Development. Differential Apoptotic and Proliferative Activities of Wild-type FOXL2 and Blepharophimosis-ptosis-epicanthus Inversus Syndrome (BPES)-associated Mutant FOXL2 Proteins Men with either type are unaffected reproductively, because FOXL2’s role in the testes is far less critical than its role in the ovaries.
This distinction matters enormously for genetic counseling. A family told that their daughter has BPES needs to know which type she carries, because the reproductive implications shape decades of medical planning. Unfortunately, determining the type on clinical grounds alone can be difficult in childhood, since ovarian failure in Type I usually becomes apparent only at puberty or later. Genetic testing of the specific FOXL2 mutation provides the most reliable prediction, though even genetic results come with caveats about variability.
The FOXL2 Gene and How It Causes BPES
Both types of BPES trace back to mutations in FOXL2, a gene that encodes a transcription factor, a protein whose job is to switch other genes on or off at the right time during development.4Human Molecular Genetics. Spectrum of FOXL2 gene mutations in blepharophimosis-ptosis-epicanthus inversus (BPES) families demonstrates a genotype-phenotype correlation FOXL2 has two completely distinct developmental roles: one in building the eyelids and surrounding facial structures, and another in maintaining the ovary. When the gene is disrupted, one or both of those roles can suffer.
On the eyelid side, FOXL2 is expressed in cells around the developing eye during a narrow window of embryonic development. Mouse studies have shown that FOXL2 acts in cranial neural crest cells, which give rise to the connective tissue around the eye and are essential for the formation of the levator palpebrae superioris, the muscle that lifts the upper lid. When FOXL2 is inactivated in those cells, the levator muscle is severely underdeveloped, producing the ptosis that characterizes BPES.5Human Molecular Genetics. Etiology of craniofacial malformations in mouse models of blepharophimosis, ptosis and epicanthus inversus syndrome Related research found that signaling through the Notch pathway can suppress FOXL2 in the periocular tissue, also leading to impaired eyelid levator muscle formation, reinforcing FOXL2’s central role in eyelid development.6Journal of Cell Science. Notch gain of function in mouse periocular mesenchyme downregulates FoxL2 and impairs eyelid levator muscle formation, leading to congenital blepharophimosis
On the ovarian side, FOXL2 is required in the somatic cells that surround each egg, called granulosa cells. Without functional FOXL2, the earliest follicles fail to progress past the primordial stage, meaning the eggs never mature and the ovary gradually degenerates.7Human Molecular Genetics. Foxl2 disruption causes mouse ovarian failure by pervasive blockage of follicle development Recent work has shown that FOXL2 interacts with different binding partners depending on the developmental stage, regulating follicle formation early on and steroidogenesis later.8PubMed Central. FOXL2 interaction with different binding partners regulates the dynamics of ovarian development The dual role of a single gene in two seemingly unrelated tissues is part of what makes BPES unusual and also explains why some mutations knock out both functions while others spare the ovary.
How Different Mutations Lead to Different Outcomes
The relationship between which FOXL2 mutation a person carries and whether they develop Type I or Type II is real but imperfect. A large compendium of FOXL2 variants identified 413 unique genetic defects across 864 patients, with about 87% of patients carrying a mutation in the coding sequence of the gene itself. A known mutational hotspot involves the polyalanine tract, a repetitive stretch of the amino acid alanine within the protein, accounting for about 24% of pathogenic variants.9Human Mutation. Variant Curation of the Largest Compendium of FOXL2 Coding and Noncoding Sequence and Structural Variants in BPES
As a general pattern, mutations that produce a severely truncated protein, one missing the functional DNA-binding domain, almost always cause Type I. Expansions of the polyalanine tract tend to cause the milder Type II, presumably because the resulting protein retains partial function.10Fertility and Sterility. A new FOXL2 gene mutation in a woman with premature ovarian failure and sporadic blepharophimosis-ptosis-epicanthus inversus syndrome But the reality is messier than that tidy scheme suggests. Several mutations have been found to cause Type I in one family and Type II in another, and some families show variability even among siblings carrying the same mutation. One well-documented example involves a truncating mutation that was expected to produce Type I but instead caused Type II in some pedigrees, challenging the earlier genotype-phenotype framework.11American Journal of Human Genetics. FOXL2 and BPES: Mutational Hotspots, Phenotypic Variability, and Revision of the Genotype-Phenotype Correlation
This variability is a genuine clinical headache. A genetic counselor can look at a family’s specific mutation and give an educated guess about ovarian risk, but for certain mutations, the answer is honestly uncertain. Other genetic modifiers, epigenetic factors, or environmental influences may tip the balance in ways that are not yet understood.
Mutations Outside the Gene Itself
About 13% of BPES patients have no mutation in the FOXL2 coding sequence at all, which puzzled geneticists for years. The explanation, at least in part, lies in regions of DNA surrounding the gene. Several families with classic BPES have been found to carry deletions or rearrangements located hundreds of thousands of base pairs upstream or downstream of FOXL2, in stretches of DNA that do not encode any protein. These non-coding regions contain regulatory sequences, essentially molecular switches that control where and when FOXL2 is turned on. Disrupting those switches can silence the gene just as effectively as breaking the gene itself.12PubMed Central. Deletions involving long-range conserved nongenic sequences upstream and downstream of FOXL2 as a novel disease-causing mechanism in blepharophimosis syndrome
In one research series, these extragenic rearrangements accounted for about 5% of all identified BPES-causing defects, and they made up 14% of cases that had initially tested negative for mutations within the gene.13The American Journal of Human Genetics. Genomic Rearrangements Encompassing or Outside of FOXL2 Cause Blepharophimosis-Ptosis-Epicanthus Inversus Syndrome For families undergoing genetic testing, this has a practical implication: a negative result from sequencing the FOXL2 gene alone does not rule out BPES. Broader analysis looking at copy number changes and structural rearrangements in the surrounding region may be necessary to find the cause.
Inheritance and Sporadic Cases
BPES follows autosomal dominant inheritance with high penetrance, meaning that most people who carry a FOXL2 mutation will show the syndrome. In family studies, the condition has been observed passing vertically across generations regardless of sex, with all affected individuals confirmed as carriers of a single heterozygous mutation.14PubMed Central. Clinical and genetic studies of 17 Han Chinese pedigrees and 31 sporadic patients with blepharophimosis-ptosis-epicanthus inversus syndrome Each child of an affected parent has a 50% chance of inheriting the condition.
That said, a substantial proportion of cases arise spontaneously without any family history. These “de novo” mutations are especially common in Type I, which makes sense: since Type I causes female infertility, the mutation is less likely to be passed along maternally. When a child is diagnosed with BPES and neither parent shows eyelid signs, a new mutation is the most likely explanation, though the parents should still be examined carefully because milder forms can go unrecognized.
Surgical Correction
Surgery is the standard treatment for the eyelid features of BPES. No medication can correct the structural abnormalities, and the surgery typically addresses multiple components in either one or two stages.15PubMed Central. Surgical Management of Blepharophimosis-Ptosis-Epicanthus Inversus Syndrome (BPES): A Comprehensive Review The classic approach involves two stages: first, correcting the epicanthus inversus and telecanthus through medial and lateral canthoplasties, then addressing the ptosis six to twelve months later, once the lid anatomy has settled. A series of 125 patients treated with this staged approach found that combining a Y-V flap for the skin fold, a von Ammon technique for the canthoplasty, and frontalis muscle flap suspension for the ptosis produced good functional and cosmetic results.16Annals of Plastic Surgery. A Modified Staged Surgical Intervention for Blepharophimosis-Ptosis-Epicanthus Inversus Syndrome: 125 Cases With Encouraging Results
Some surgeons prefer a one-stage approach, particularly for younger children where minimizing the number of operations and anesthesia exposures is a priority. In one series, about 78% of patients who underwent one-stage correction were under five years old.17PubMed Central. One-stage correction for blepharophimosis syndrome There is no firm consensus on which approach is superior; the choice depends on the severity of the individual case, the surgeon’s experience, and how urgently the visual axis needs to be cleared. The key point most surgeons agree on is that the epicanthus inversus and telecanthus should be dealt with before or simultaneously with the ptosis, because correcting the ptosis alone without addressing the medial skin fold gives unpredictable results.
Regardless of the surgical approach, revision procedures are common. Growing children may need adjustments as their facial proportions change, and achieving a symmetric, natural-looking result when all four features need correction at once is technically demanding.
Fertility Options for Women With Type I
For women diagnosed with Type I BPES, the reproductive window can be extremely narrow, and some women reach ovarian failure before they ever attempt pregnancy. The degree of ovarian reserve varies: some women retain a small number of functional follicles into their twenties, while others show signs of failure in their teens. This variability is another reason clinicians urge early hormonal evaluation and genetic typing in girls with BPES, because the opportunity to preserve fertility may be brief.
Assisted reproductive technologies are difficult but not impossible in this population. One case report described a successful pregnancy after ovarian stimulation with gonadotropins in a Type I patient, suggesting that even ovaries with diminished reserve can sometimes respond to aggressive hormonal therapy.18PubMed. Pregnancy in a woman with premature ovarian insufficiency associated with blepharophimosis, ptosis, epicanthus inversus syndrome type I. A case report Another case series reported the second known live birth of a biological child to a Type I patient using IVF, confirming that success is rare but feasible.19PubMed Central. Confrontment and solution to gonadotropin resistance and low oocyte retrieval in in vitro fertilization for type I BPES: a case series with review of literature
Planned oocyte cryopreservation, freezing eggs proactively, has been attempted as well, but results are mixed. In one small series, one woman successfully had eight mature oocytes frozen, while two others failed to respond to ovarian stimulation at all and their cycles were cancelled before any eggs could be retrieved.20F&S Reports. Planned oocyte cryopreservation in women with blepharophimosis-ptosis-epicanthus inversus syndrome: a case series The reality is that by the time many women with Type I BPES learn about egg freezing, their ovarian reserve may already be too depleted for it to work. Clinicians working with BPES families increasingly recommend hormonal assessment and fertility counseling in adolescence so that options like egg freezing can be explored while the ovaries still have some function.
Recognizing BPES and Avoiding Misdiagnosis
Although the four-feature combination is distinctive, BPES can be confused with other causes of congenital ptosis, especially in settings where genetic testing is not readily available. Isolated congenital ptosis is far more common than BPES and is usually caused by problems with the levator muscle or its nerve supply rather than a mutation in FOXL2. The key differentiator is the presence of epicanthus inversus and telecanthus alongside the ptosis and blepharophimosis. When clinicians see only droopy eyelids without the other three features, BPES is unlikely. Both types are inherited in an autosomal dominant pattern with high penetrance, caused by mutations in the FOXL2 gene on chromosome 3q23.21PubMed Central. A rare cause of congenital ptosis: Blepharophimosis, ptosis and epicanthus inversus syndrome
Another source of confusion is that some affected individuals, particularly those with milder mutations, may show less pronounced epicanthus inversus, making the full syndrome harder to recognize on first glance. A child with bilateral ptosis and slightly narrow eye openings might be referred to an oculoplastic surgeon without anyone suspecting BPES until a family history or genetic test reveals it. This is particularly consequential for girls, because missing a Type I diagnosis means missing the chance for early fertility planning.
FOXL2 Across the Animal Kingdom
One of the striking things about FOXL2 is how ancient and conserved it is. The gene is found in essentially all vertebrates, from fish to birds to mammals, and its role in ovarian development appears to be one of the oldest functions of any known transcription factor in reproductive biology. Comparisons of FOXL2 sequences from turtles, chickens, and mammals revealed an unusually high degree of structural conservation, suggesting that the gene has been performing the same basic job for hundreds of millions of years.22PubMed. Etiology of ovarian failure in blepharophimosis ptosis epicanthus inversus syndrome: FOXL2 is a conserved, early-acting gene in vertebrate ovarian development FOXL2 and its paralog FOXL3 have been identified across all metazoans, with their evolutionary history shaped by whole-genome duplication events in the vertebrate lineage. Across species, these genes are involved in both somatic and germ cell differentiation in the gonad.23Sexual Development. Foxl2 and Its Relatives Are Evolutionary Conserved Players in Gonadal Sex Differentiation
In goats, loss-of-function mutations in FOXL2 cause a naturally occurring condition called polled intersex syndrome, where genetically female animals develop male-like gonads. In fish, FOXL2 plays a role in maintaining the female gonadal identity even in adulthood, and disrupting it can tip the sex balance toward male development. The eyelid function appears to be a more recent evolutionary acquisition, potentially linked to the elaboration of facial muscles and eyelid structures in mammals. This deep conservation helps explain why mouse models of FOXL2 disruption so closely mimic the human disease, including female-specific infertility and craniofacial changes.24PubMed. Foxl2 function in ovarian development
For families living with BPES, this evolutionary angle may seem academic, but it has a practical upside: the exceptional conservation of FOXL2 across species means that researchers can study the gene’s function in animal models with reasonable confidence that the findings translate to humans. Mouse models lacking FOXL2 faithfully reproduce the ovarian failure seen in Type I, with follicle development arrested at the earliest stage and ovaries that eventually degenerate entirely.25Human Molecular Genetics. Foxl2 disruption causes mouse ovarian failure by pervasive blockage of follicle development Those models remain essential tools for testing potential future therapies aimed at slowing or reversing ovarian decline in affected women.