Blepharophimosis syndrome is linked to chromosome 3q

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

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.

A modified technique combining excision of the levator muscle and tarsus for blepharoptosis in Asians: a 6-year experience with 116 cases

BACKGROUND

In patients with blepharoptosis, the function of levator muscle is insufficient or completely absent, causing blepharoptosis in various degrees. For mild or moderate blepharoptosis, levator advancement or resection is commonly performed. However, in severe cases, undercorrection results and recurrence often occur even a great length of levator muscle is resected. Because the levator muscle makes the upper eyelid move in a physiologic direction, exerting the function of residual levator muscle is still a more preferred approach for correction of blepharoptosis. This study combined tarsus resection with levator resection. The resected tarsus can offset the amount of the levator excised, making this technique applicable for severe cases.

METHODS

This study included 116 patients (175 eyelids) with moderate or severe ptosis who underwent combined excision of the levator muscle and the tarsus. For cases of bilateral blepharoptosis with different levator functions between the two eyelids, surgery was performed for more severe side first and for the other side 6 months later. Postoperatively, the correction and symmetry results were evaluated and analyzed using chi-square testing by SPSS (version 10.0).

RESULTS

Adequate or normal correction was achieved in 149 eyelids (85.1%). The difference in correction results did not differ significantly between moderate and severe cases. With a two-stage operation, 98 patients (84.5%) obtained good or fair asymmetry results, and no statistically significant difference existed between the bilateral and unilateral cases.

CONCLUSION

The described technique appears to be effective for both moderate and severe ptosis, with better biomechanics and a satisfying aesthetic outcome.

A new non-incisional correction method for blepharoptosis

PURPOSE

The present report introduces our correction method for blepharoptosis, in which major incisions are made on neither the skin nor the conjunctiva of the upper eyelid, and no dissection of the eyelid tissues is required.

METHODS

After turning the upper eyelid inside out, threads are introduced into it through the conjunctiva close to the superior fornix. Then the superior palpebral levator muscle and the tarsus are connected using threads. This thread application is performed at two-to-four locations of the upper eyelid. By tightening the threads, the tarsus is elevated and the ptotic eyelid is corrected. A total of 624 eyelids in 390 patients with mild or moderate ptosis were operated on with this surgical method. Effectiveness of the treatment was evaluated referring to the degree of improvement. Furthermore, frequencies of complications were evaluated.

RESULTS

Among 416 eyelids with mild ptosis, complete correction of ptosis was achieved with 406 eyelids (97.5%). Among 208 eyelids with moderate ptosis, improvement was achieved with 185 eyelids (88.9%), with complete correction for 156 eyelids (75%).

CONCLUSION

Since the present method enables effective correction of the blepharoptosis with a simple technique, minimised recovery time and no scarring, it provides a useful surgical option for the treatment of mild and moderate blepharoptosis.

FOXL2 gene mutations and blepharophimosis-ptosis-epicanthus inversus syndrome (BPES): a novel mutation detected in a Chinese family and a statistic model for summarizing previous reported records

Previous studies found that the forkhead transcription factor 2 (FOXL2) gene mutations are responsible for both types of blepharophimosis-ptosis-epicanthus inversus syndrome (BPES) but have not established any systematic statistic model for the complex and even contradictory results about genotype-phenotype correlations between them. This study is aimed to find possible mutations of FOXL2 gene in a Chinese family with type II BPES by using DNA sequencing and to further clarify genotype-phenotype correlations between FOXL2 mutations and BPES by using a systematic statistical method, namely Multifactor Dimensionality Reduction (MDR). A novel mutation (g.933_965dup) which could result in an expansion of the polyalanine (polyAla) tract was detected in all patients of this family. MDR analysis for intragenic mutations of FOXL2 gene reported in previous BPES studies indicated that the mutations which led to much stronger disturbance of amino acid sequence were responsible for more type I BPES, while other kinds of mutation were responsible for more type II BPES. In conclusion, the present study found a novel FOXL2 gene mutation in a Chinese BPES family and a new general genotype-phenotype correlation tendency between FOXL2 intragenic mutations and BPES, both of which expanded the knowledge about FOXL2 gene and BPES.

Shox2-deficient mice exhibit a rare type of incomplete clefting of the secondary palate

The short stature homeobox gene SHOX is associated with idiopathic short stature in humans, as seen in Turner syndrome and Leri-Weill dyschondrosteosis, while little is known about its close relative SHOX2. We report the restricted expression of Shox2 in the anterior domain of the secondary palate in mice and humans. Shox2-/- mice develop an incomplete cleft that is confined to the anterior region of the palate, an extremely rare type of clefting in humans. The Shox2-/- palatal shelves initiate, grow and elevate normally, but the anterior region fails to contact and fuse at the midline, owing to altered cell proliferation and apoptosis, leading to incomplete clefting within the presumptive hard palate. Accompanied with these cellular alterations is an ectopic expression of Fgf10 and Fgfr2c in the anterior palatal mesenchyme of the mutants. Tissue recombination and bead implantation experiments revealed that signals from the anterior palatal epithelium are responsible for the restricted mesenchymal Shox2 expression. BMP activity is necessary but not sufficient for the induction of palatal Shox2 expression. Our results demonstrate an intrinsic requirement for Shox2 in palatogenesis, and support the idea that palatogenesis is differentially regulated along the anteroposterior axis. Furthermore, our results demonstrate that fusion of the posterior palate can occur independently of fusion in the anterior palate.

A novel insertion mutation in the FOXL2 gene is detected in a big Chinese family with blepharophimosis-ptosis-epicanthus inversus

Blepharophimosis-ptosis-epicanthus inversus syndrome (BPES), an autosomal dominant syndrome in which an eyelid malformation is associated (type I) or not (type II) with premature ovarian failure (POF), has recently been ascribed to mutations in the forkhead transcription factor 2 (FOXL2) gene. In this work, we reveal a novel insertion mutation in the 3'UTR of the FOXL2 gene in a big Chinese family which is to our knowledge the first BPES (type II) family reported in China. It is the first time that a 3'UTR mutation in the FOXL2 gene has ever been found to demonstrate a close correlation between genotype and BPES. Our result gains a greater insight into the function of 3'UTR in the FOXL2 gene.

Comparative analysis of the FOXL2 gene and characterization of mutations in BPES patients

Bleparophimosis ptosis epicanthus inversus syndrome (BPES) is a rare disorder characterized by eyelid malformation and in some cases associated with premature ovarian failure. Although the familial form is autosomal dominant, many cases are also sporadic. The mutations causing this disorder were found in a winged/forkhead transcription factor gene named FOXL2. We have sequenced the mouse homolog for the FOXL2 gene and identified the Fugu rubripes (pufferfish) ortholog from the database. By alignment of the three sequences, we found an almost complete conservation of the forkhead domain in the three species. There is 95% and 61% conservation at the protein level between human-mouse and human-pufferfish, respectively. The polyalanine and polyproline tracts within the gene are absent in Fugu rubripes. An overview identifies four breaks in the conservation of the gene within these species. Using a direct sequencing approach, we performed mutation analysis from DNA of nine affected individuals from familial and sporadic cases. The mutations are distributed throughout the coding region of the FOXL2 gene. We identified five novel mutations: g.292delG (E19fsX149); g.530G>A (W98X); g.548A>G (H104R); g.652G>T (E139X); and g.1178_1185del8 (A314fsX530). In addition we also identified two known mutations g.823C>T (Q196X) and g.1092_1108dup17, the latter in individuals from three unrelated pedigrees.

FOXL2 and BPES: mutational hotspots, phenotypic variability, and revision of the genotype-phenotype correlation

Blepharophimosis syndrome (BPES), an autosomal dominant syndrome in which an eyelid malformation is associated (type I) or not (type II) with premature ovarian failure (POF), has recently been ascribed to mutations in FOXL2, a putative forkhead transcription factor gene. We previously reported 22 FOXL2 mutations and suggested a preliminary genotype-phenotype correlation. Here, we describe 21 new FOXL2 mutations (16 novel ones) through sequencing of open reading frame, 5' untranslated region, putative core promoter, and fluorescence in situ hybridization analysis. Our study shows the existence of two mutational hotspots: 30% of FOXL2 mutations lead to polyalanine (poly-Ala) expansions, and 13% are a novel out-of-frame duplication. In addition, this is the first study to demonstrate intra- and interfamilial phenotypic variability (both BPES types caused by the same mutation). Furthermore, the present study allows a revision of the current genotype-phenotype correlation, since we found exceptions to it. We assume that for predicted proteins with a truncation before the poly-Ala tract, the risk for development of POF is high. For mutations leading to a truncated or extended protein containing an intact forkhead and poly-Ala tract, no predictions are possible, since some of these mutations lead to both types of BPES, even within the same family. Poly-Ala expansions may lead to BPES type II. For missense mutations, no correlations can be made yet. Microdeletions are associated with mental retardation. We conclude that molecular testing may be carefully used as a predictor for POF risk in a limited number of mutations.

Two families with blepharophimosis/ptosis/epicanthus inversus syndrome have mutations in the putative forkhead transcription factor FOXL2

Blepharophimosis/ptosis/epicanthus inversus syndrome (BPES) is an autosomal dominant disorder that is characterized by distinctive eyelid abnormalities. Two clinical subtypes have been described in which type I, but not type II, is associated with premature ovarian failure. Both types of BPES are linked to 3q22-23, and the gene has recently been identified as the putative forkhead transcription factor FOXL2. We report mutation screening of FOXL2 in two families with this condition. The two mutations detected were frameshift mutations resulting from a small insertion or duplication within the gene. Both mutations would result in the production of novel carboxyl terminii, one terminating the predicted protein earlier than the wild type, and the other giving rise to a larger protein product, assuming these proteins or their mRNA were not degraded. Based on the present data, this would suggest that the first family should be type I and the second, type II. Although there is evidence of infertility in the first family, all 3 females in the youngest generation have normal pelvic ultrasound and hormone levels, suggesting that the divide between types I and II may not be as distinct as has been suggested.

The putative forkhead transcription factor FOXL2 is mutated in blepharophimosis/ptosis/epicanthus inversus syndrome

In type I blepharophimosis/ptosis/epicanthus inversus syndrome (BPES), eyelid abnormalities are associated with ovarian failure. Type II BPES shows only the eyelid defects, but both types map to chromosome 3q23. We have positionally cloned a novel, putative winged helix/forkhead transcription factor gene, FOXL2, that is mutated to produce truncated proteins in type I families and larger proteins in type II. Consistent with an involvement in those tissues, FOXL2 is selectively expressed in the mesenchyme of developing mouse eyelids and in adult ovarian follicles; in adult humans, it appears predominantly in the ovary. FOXL2 represents a candidate gene for the polled/intersex syndrome XX sex-reversal goat.

X linked dominant congenital isolated bilateral ptosis: the definition and characterisation of a new condition

AIMS

To characterise the inheritance of ptosis in one particular pedigree.

METHODS

The pedigree was analysed clinically and genetically to assess the mode of inheritance and to ascribe a gene locus for the condition.

RESULTS

Affected members of the pedigree have bilateral symmetrical congenital isolated ptosis, a condition which is linked to genetic markers on the X chromosome in this family.

CONCLUSION

A pedigree with dominantly inherited congenital bilateral ptosis is presented. The pedigree exhibits X linked dominant inheritance. A new ophthalmic condition was thereby characterised-namely, X linked dominant congenital isolated bilateral ptosis.

Identification of BPESC1, a novel gene disrupted by a balanced chromosomal translocation, t(3;4)(q23;p15.2), in a patient with BPES

The blepharophimosis syndrome (BPES) is a rare genetic disorder characterized by blepharophimosis, ptosis, epicanthus inversus, and telecanthus. In type I, BPES is associated with female infertility, while in type II, the eyelid defect occurs by itself. The BPES syndrome has been mapped to 3q23. Previously, we constructed a YAC-, PAC-, and cosmid-based physical map surrounding the 3q23 translocation breakpoint of a t(3;4)(q23;p15.2) BPES patient, containing a 110-kb PAC (169-C 10) and a 43-kb cosmid (11-L 10) spanning the breakpoint. In this report, we present the identification of BPESC1 (BPES candidate 1), a novel candidate gene that is disrupted by the translocation on chromosome 3. Cloning of the cDNA has been performed starting from a testis-specific EST, AI032396, found in cosmid 11-L 10. The cDNA sequence of BPESC1 is 3518 bp in size and contains an open reading frame of 351 bp. No significant similarities with known proteins have been found in the sequence databases. BPESC1 contains three exons and spans a genomic fragment of 17.5 kb. Expression of BPESC1 was observed in adult testis tissue. We performed mutation analysis in 28 unrelated familial and sporadic BPES patients, but, apart from the disruption by the translocation, found no other disease-causing mutations. These data make it unlikely that BPESC1 plays a major role in the pathogenesis of BPES.

Molecular cytogenetic evaluation in a patient with a translocation (3;21) associated with blepharophimosis, ptosis, epicanthus inversus syndrome (BPES)

Blepharophimosis, ptosis, epicanthus inversus syndrome type I (BPES; OMIM 110100) is an autosomal dominant disorder affecting craniofacial development and ovarian function. We have identified a patient with BPES who carried a de novo reciprocal translocation [46, XX,t(3;21)(q23;q22.1)]. Fluorescence in situ hybridization analysis at band 3q23 using probes derived from BAC 175G20 (Research Genetics), PACs 108L15 and 169C10 (RPCI1), and cosmids AC174D4, AC68D3, AC44F5, and AC125C5 (Lawrence Livermore National Laboratory) was performed. The patient's breakpoint was found to lie within the overlapping region of the BAC and PACs but centromeric to all the cosmids. However, a 10.5-kb BamHI-digested fragment, common to the BAC and PAC clones, was shown to cross the breakpoint. The results have placed our patient's breakpoint proximal to that of the previously reported patient [46,XY,t(3;4)(q23;p15.2)] and within a 10.5-kb interval. This is the second patient in which a breakpoint was refined by molecular cytogenetics. Our findings emphasize the significance of this region for BPES.

Closing in on the BPES gene on 3q23: mapping of a de Novo reciprocal translocation t(3;4)(q23;p15.2) breakpoint within a 45-kb cosmid and mapping of three candidate genes, RBP1, RBP2, and beta'-COP, distal to the breakpoint

BPES is a genetic disorder presenting with blepharophimosis, ptosis of the eyelids, epicanthus inversus, and telecanthus. BPES type I is associated with female infertility, whereas type II presents without additional symptoms. Hitherto, it remains unknown whether BPES type I results from a defect in a single gene or from a contiguous gene syndrome. Previous cytogenetic and linkage analyses have assigned a BPES locus to 3q23, in a 5-cM interval between D3S1615 and D3S1316. In this report, we describe the molecular and physical characterization of the 3q23 breakpoint in a BPES patient with a t(3;4)(q23;p15.2) translocation. Eight YACs located around and within the D3S1615-D3S1316 interval were mapped relative to the 3q23 breakpoint; 5 YACs spanning the 3q23 breakpoint were identified. Thirteen STSs and ESTs were localized on the YAC map. Subsequent hybridization of 2 YACs spanning the breakpoint to the Human RPCI1 PAC Library and the Human Chromosome 3 LLNL Cosmid Library resulted in the identification of 12 PACs and 50 cosmids respectively, allowing the construction of a detailed PAC and cosmid physical map. A refined position-telomeric to the breakpoint-of 3 candidate genes, cellular retinol-binding proteins 1 and 2 (RBP1, RBP2) and the coatomer beta' subunit (beta'-COP), was obtained on this physical map. Furthermore, a PAC and cosmid contig encompassing the breakpoint was constructed. PAC 169-C 10 and cosmid 11-L 10 crossing the breakpoint have sizes of 110 and 45 kb, respectively. The isolation of coding sequences in these clones and in the rest of the contig will greatly facilitate further efforts toward positional cloning of the gene(s) involved in BPES.

Refinement of a translocation breakpoint associated with blepharophimosis-ptosis-epicanthus inversus syndrome to a 280-kb interval at chromosome 3q23

Blepharophimosis syndrome (BPES) is an autosomal dominant disorder of craniofacial development, the features of which include blepharophimosis, ptosis, and epicanthus inversus. Although it has been suggested that BPES is genetically heterogeneous, a major locus for this condition resides at chromosome 3q23. We have previously mapped a translocation breakpoint associated with BPES to the D3S1316-D3S1615 interval. The markers in this region have subsequently been shown to lie in a different order, with the BPES locus mapping to the 1-cM D3S1576 and D3S1316 interval. In the current investigation, a physical map, consisting of 60 yeast artificial chromosome (YAC) clones and 1 bacterial artificial chromosome, that spans this region has been constructed. Ten expressed sequence tags and the cellular retinol-binding protein I locus have been mapped to the contig. YAC end isolation has led to the creation of novel STSs that have been used to reduce the size of the BPES critical region to a 280-kb interval, which has been cloned in two nonchimeric YACs.

Deletion 3q in two patients with blepharophimosis-ptosis-epicanthus inversus syndrome (BPES)

BACKGROUND

Blepharophimosis-ptosis-epicanthus inversus syndrome (BPES) is an autosomal dominant condition mapped to chromosome 3q23. There are several reports of chromosomal abnormalities involving this region with a resultant phenotype that includes BPES.

METHOD

We reassessed two unrelated boys ages 3 and 5 with BPES and associated nonocular abnormalities. Karyotype, which had been previously reported as normal, was repeated using high-resolution banding techniques, to look specifically at 3q23. Clinical findings were tabulated and compared with previously reported cases.

RESULTS

Both patients proved to have interstitial deletions of chromosome 3, the first involving bands q22.2q25.1 and the second q22.2q24. The first patient exhibited prenatal and postnatal growth retardation, with global developmental delay, while the second patient had normal growth and development except for speech delay. Both had dysmorphic facies with BPES, flat philtrum, a thin upper lip, and small chin. In addition, the first boy had an inguinal hernia and hypospadius; the second boy had abnormal auricles and metatarsus adductus. The eight cases of interstitial deletions of 3q2 and six rearrangements involving this region have a remarkably similar phenotype.

CONCLUSIONS

Deletion of 3q23 is a recognizable contiguous gene syndrome. Microdeletions of 3q23 should be ruled out in any sporadic case of BPES especially if there are associated nonocular abnormalities.

Blepharophimosis: a causally heterogeneous malformation frequently associated with developmental disabilities

We report on 22 individuals referred for genetic evaluation because of blepharophimosis. Fourteen of these patients had the blepharophimosis syndrome: 5 familial and 9 sporadic. Mental retardation or developmental delay was seen in 8 of the 12 children in whom this could be assessed. Eight of 22 children had a malformation syndrome other than the blepharophimosis syndrome. All 8 of these children were mentally retarded or developmentally delayed. Two of these 8 had recognized disorders (branchio-oto-renal syndrome and a ring 4 chromosome); the remaining 6 had unrecognized malformation syndromes. Based on this information, it is suggested that children with blepharophimosis be evaluated carefully for underlying conditions and that they be observed for developmental disabilities because of the frequent association.

A novel case of unilateral blepharophimosis syndrome and mental retardation associated with de novo trisomy for chromosome 3q

We have evaluated a 3 2/12 year old girl who presented with unilateral blepharophimosis, ptosis of the eyelid, and mental retardation. Additional dysmorphic features include microcephaly, high, narrow forehead, short stubby fingers, and adduction of the right first toe. Cytogenetic analysis showed an unbalanced karyotype consisting of 46,XX,add(7)(q+) that was de novo in origin. Fluorescence in situ hybridisation (FISH) using microdissected library probe pools from chromosomes 1,2,3,7, and 3q26-qter showed that the additional material on 7q was derived from the distal end of the long arm of chromosome 3. Our results indicate that the patient had an unbalanced translocation, 46,XX,der(7)t(3;7)(q26-qter;q+) which resulted in trisomy for distal 3q. All currently reported cases of BPES (blepharophimosis-ptosis-epicanthus inversus syndrome) with associated cytogenetic abnormalities show interstitial deletions or balanced translocations involving 3q22-q23 or 3p25.3. Our patient shares similar features to BPES, except for the unilateral ptosis and absence of epicanthus inversus. It is possible that our patient has a contiguous gene defect including at least one locus for a type of blepharophimosis, further suggesting that multiple loci exist for eyelid development.

Linkage analysis in blepharophimosis-ptosis syndrome confirms localisation to 3q21-24

Blepharophimosis-ptosis is an autosomal dominant disorder in which previous chromosome rearrangements have suggested a putative gene location on the long arm of chromosome 3. This paper confirms the location at 3q21-24 with linkage studies in two large families. A lod score of 3·2 was found with D3S1237.