ADAMTSL4 assessment in ectopia lentis reveals a recurrent founder mutation in Polynesians

A novel ADAMTSL4 compound heterozygous mutation in isolated ectopia lentis: a case report and review of the literature

BACKGROUND

Congenital ectopia lentis is characterized by dislocation of the lens caused by partial or complete abnormalities in the zonular fibers. It can be caused by either systemic diseases or isolated ocular diseases. Gene detection techniques can provide valuable information when an etiological diagnosis is challenging. Herein, we report the case of a six-year-old girl with a confirmed diagnosis of isolated ectopia lentis caused by a compound heterozygous ADAMTSL4 gene mutation.

CASE PRESENTATION

The patient was a 6-year-old Chinese Han girl with strabismus in the right eye. Slit lamp examination revealed that the lens in the right eye was opacified and dislocated, without an ectopic pupil. Gene detection demonstrated the presence of a compound heterozygous mutation in the ADAMTSL4 gene [c. 2270dupG (p.Gly758Trpfs *59) and c. 2110A > G (p.Ser704Gly)], and the diagnosis of isolated ectopia lentis was confirmed. She underwent lens extraction, and a sutured scleral-fixated posterior chamber intraocular lens (IOL) was placed in the right eye. The best-corrected visual acuity was 0.1 one month postoperatively.

CONCLUSION

Gene detection plays a crucial role in diagnosing disorders with similar symptoms, such as isolated ectopia lentis and Marfan syndrome. In this study, we used whole exons sequencing to diagnose isolated ectopia lentis and identified the variant c.2110A > G (p.Ser704Gly), which may be associated with the development of ectopia lentis and early-onset cataract in the patient. These pathogenic gene mutations have significant implications for the genetic diagnosis of congenital ectopia lentis, treatment, surveillance, and hereditary and prenatal counseling for the patient and their family members.

Biallelic ADAMTSL4 variants in a Chinese cohort of congenital ectopia lentis: Implications for genotype-phenotype relationships

ADAMTSL4 variants are one of the common causes of congenital ectopia lentis (EL), reported ocular comorbidities of which include iris anomalies, cataract, and glaucoma. However, a genotype-phenotype correlation has not been established. Potentially pathogenic ADAMTSL4 variants were screened from a Chinese cohort of congenital EL using panel-based next-generation sequencing followed by multiple bioinformatics analyses. The genotype-phenotype correlation was assessed via a systematic review of ADAMTSL4 variants within our data and those from the literature. A total of 12 variants of ADAMTSL4, including seven frameshift variants, one nonsense variant, two splicing variants, and two missense variants, were found in nine probands. Combing genetic and clinical information from 72 probands in the literature revealed 37 ADAMTSL4 variants known to cause EL, and the ethnic difference was prominent. The lens was inclined to dislocate inferior temporally (22, 27.16%), while the pupil was always located oppositely (9, 81.82%). Several anterior segments anomalies were identified, including ectopia pupillae (15, 18.52%), persistent pupillary membrane (9, 11.10%), poor pupil dilation (4, 30.8%), cataract (13, 24.10%), and glaucoma (8, 13.33%). Genotype-phenotype analysis revealed that truncation variants had higher risks of combined iris anomalies, including either ectopia pupillae or a persistent pupillary membrane (p =  0.007). The data from this study not only extend our knowledge of the ADAMTSL4 variant spectrum but also suggest that deleterious variants of ADAMTSL4 might be associated with severe ocular phenotypes.

Correlation between novel compound heterozygous ADAMTSL4 variants and primary phenotypes of ectopia lentis et pupillae

PURPOSE

To investigate molecular pathogenesis of congenital ectopia lentis accompanied by various ophthalmic manifestations in a pedigree.

METHODS

Three female siblings, their spouse and offspring underwent ophthalmic and general medical examinations. Genetic variants were screened with the whole exome sequencing and analyzed in either a dominant or recessive inheritance manner. Gene mutations were ascertained with the Sanger sequencing after the polymerase chain reaction.

RESULTS

All three female siblings were diagnosed as the Ectopia lentis et pupillae (ELeP) through combination of clinical examination and genetic analysis. No characteristic pathological changes of skeletal, metabolic and cardiac abnormalities were observed. Thirteen genetic variants were selected out through analyzing in the dominant or recessive inheritance manner, but they were not associated with EL. Among them, ALOX15B variant may explain the skin disease in this pedigree. After inspection the known genes related to EL, novel compound heterozygous mutations (p.Ser264LeufsX37/p.Gly757ValfsX62) in ADAMTSL4 were discreetly identified in this ELeP pedigree.

CONCLUSIONS

Novel compound heterozygous ADAMTSL4 variants are responsible for ELeP in the current pedigree. Correlation between ADAMTSL4 variants and ELeP was firstly established based on our 12 years follow-up studies and previous reports of ELeP and of ADAMTSL4-related eye disorders. The primary phenotypes caused by ADAMTSL4 variants include EL, EP, poor pupillary dilation, and axial elongation. Highly varying phenotypes including glaucoma, high myopia retinapathy, and poor vision and so on may be the secondary impairments. All these secondary impairments may be improved if proper clinical interventions are implemented in time.

ADAMTSL4-related ectopia lentis: A case of pseudodominance with an asymptomatic parent

Pathogenic variants of ADAMTSL4 are associated with autosomal recessive ectopia lentis et pupillae and isolated ectopia lentis, often presenting congenitally or in childhood. We describe a pedigree of a 4-year-old female child with bilateral ectopia lentis and her asymptomatic 35-year-old father with mild anterior segment findings. Molecular evaluation revealed compound heterozygosity for ADAMTSL4 pathogenic variants in the proband and homozygosity for an ADAMTSL4 pathogenic founder mutation in her father. The results of genetic testing revealed a pseudodominant inheritance pattern in the family. This case expands variability of ADAMTSL4-related ectopia lentis through the first description of an asymptomatic adult in the 4th decade and highlights importance of clinical and molecular evaluations of family members when investigating genetic disorders.

Novel ADAMTSL4 gene mutations in Chinese patients with isolated ectopia lentis

Background

To characterise the phenotype and genetic defects of isolated ectopia lentis (IEL) and to determine the ADAMTSL4 gene mutation frequencies in a Chinese congenital ectopia lentis (CEL) cohort.

Methods

In total, 127 Chinese probands with a clinical CEL diagnosis were recruited for this study and underwent ocular and systemic examinations. Whole-exome sequencing was used to detect variants, and Sanger sequencing and bioinformatics analysis verified the pathogenic mutations.

Results

Overall, biallelic mutations in ADAMTSL4, involving 8 novel ADAMTSL4 mutations (c.21–2A>G, c.1174G>C, c.2169C>A, c.2236C>T, c.2263delG, c.2397C>A, c.2488dupC and c.2935T>C) were identified in 5 probands (5/127, 3.94%) with IEL. Additionally, four patients had combined congenital cataracts, and two patients had ectopia lentis et pupillae (ELP). One of eight mutations was a homozygous missense mutation, and the other seven mutations were compound heterozygous. These eight consisted of three missense (37.5%), three frameshift (37.5%), one stop-gain (12.5%) and one spicing mutation (12.5%). These mutations co-segregated with the IEL, and the substitution of amino acids greatly affected conserved residues. Most of the novel mutations were located in the thrombospondin type 1 (TSP1) domain, which ultimately alters the structure of the ADAMTSL4 protein.

Conclusions

This study reported five IEL probands with eight novel mutations in the ADAMTSL4 gene. The clinical IEL phenotypes caused by these mutations were variable and complex. This study thus establishes the ADAMTSL4 gene mutation frequency and expands the gene’s mutation spectrum to help recognise ADAMTSL4-related IEL clinical manifestations.

Molecular and phenotypic investigation of a New Zealand cohort of childhood-onset retinal dystrophy

Inherited retinal diseases are clinically heterogeneous and are associated with nearly 300 different genes. In this retrospective, observational study of a consecutive cohort of 159 patients (134 families) with childhood-onset (<16 years of age) retinal dystrophy, molecular investigations, and in-depth phenotyping were performed to determine key clinical and molecular characteristics. The most common ocular phenotype was rod-cone dystrophy in 40 patients. Leber Congenital Amaurosis, the most severe form of retinal dystrophy, was present in 10 patients, and early onset severe retinal dystrophy in 22 patients. Analysis has so far identified 131 pathogenic or likely pathogenic variants including 22 novel variants. Molecular diagnosis was achieved in 112 of 134 families (83.6%) by NGS gene panel investigation in 60 families, Sanger sequencing in 27 families, and Asper microarray in 25 families. An additional nine variants of uncertain significance were also found including three novel variants. Variants in 36 genes have been identified with the most common being ABCA4 retinopathy in 36 families. Five sporadic retinal dystrophy patients were found to have variants in dominant and X-linked genes (CRX, RHO, RP2, and RPGR) resulting in more accurate genetic counseling of inheritance for these families. Variants in syndromic associated genes including ALMS1, SDCCAG8, and PPT1 were identified in eight families enabling directed systemic care.

Microcornea and Thickened Lens in Angle Closure following Nonsurgical Treatment of Retinopathy of Prematurity

Purpose

To characterize the clinical features in young patients with angle closure and to determine the characteristics associated with acquired anterior segment abnormality following retinopathy of prematurity (ROP) treatment.

Methods

We performed two retrospective case-control series. In the first series, we identified consecutive young angle closure patients without prior surgeries, with and without a history of ROP treatment; in the second series we identified consecutive patients who underwent ROP treatment, without and without anterior segment changes.

Results

In the first series, 25 eyes of 14 consecutive angle closure patients were included: 19 eyes (11 patients, 78.6%) had a history of treated ROP, while 6 eyes (3 patients) belonged to full-term patients. The treated ROP eyes had significantly shallower anterior chambers (1.77 ± 0.17 mm vs 2.72 ± 0.18 mm, P < 0.0001) and thicker lenses (5.20 ± 0.54 mm vs 3.98 ± 0.20 mm, P = 0.0002) compared to the full-term controls. In the second series, 79 eyes of 40 patients were included, with median gestational age of 24.6 weeks. Acquired iridocorneal adhesion was noted in the eight eyes (10.1%) at a mean age of 4.7 years and was associated with prior zone 1 and plus disease (P = 0.0013), a history of initial intravitreal bevacizumab treatment (IVB, P = 0.0477) and a history of requiring additional IVB after initial treatment (P = 0.0337).

Conclusions

Many young angle closure patients may have a history of treated ROP and may present with the triad of increased lens thickness, microcornea, and angle closure.

NGS panel analysis in 24 ectopia lentis patients; a clinically relevant test with a high diagnostic yield

BACKGROUND

Several genetic causes of ectopia lentis (EL), with or without systemic features, are known. The differentiation between syndromic and isolated EL is crucial for further treatment, surveillance and counseling of patients and their relatives. Next generation sequencing (NGS) is a powerful tool enabling the simultaneous, highly-sensitive analysis of multiple target genes.

OBJECTIVE

The aim of this study was to evaluate the diagnostic yield of our NGS panel in EL patients. Furthermore, we provide an overview of currently described mutations in ADAMTSL4, the main gene involved in isolated EL.

METHODS

A NGS gene panel was analysed in 24 patients with EL.

RESULTS

A genetic diagnosis was confirmed in 16 patients (67%). Of these, four (25%) had a heterozygous FBN1 mutation, 12 (75%) were homozygous or compound heterozygous for ADAMTSL4 mutations. The known European ADAMTSL4 founder mutation c.767_786del was most frequently detected.

CONCLUSION

The diagnostic yield of our NGS panel was high. Causative mutations were exclusively identified in ADAMTSL4 and FBN1. With this approach the risk of misdiagnosis or delayed diagnosis can be reduced. The value and clinical implications of establishing a genetic diagnosis in patients with EL is corroborated by the description of two patients with an unexpected underlying genetic condition.