Exome sequencing in patients with microphthalmia, anophthalmia, and coloboma (MAC) from a consanguineous population.

Next-generation sequencing strategies have resulted in mutation detection rates of 21% to 61% in small cohorts of patients with microphthalmia, anophthalmia and coloboma (MAC), but despite progress in identifying novel causative genes, many patients remain without a genetic diagnosis. We studied a cohort of 19 patients with MAC who were ascertained from a population with high rates of consanguinity. Using single nucleotide polymorphism (SNP) arrays and whole exome sequencing (WES), we identified one pathogenic variant in TENM3 in a patient with cataracts in addition to MAC. We also detected novel variants of unknown significance in genes that have previously been associated with MAC, including KIF26B, MICU1 and CDON, and identified variants in candidate genes for MAC from the Wnt signaling pathway, comprising LRP6, WNT2B and IQGAP1, but our findings do not prove causality. Plausible variants were not found for many of the cases, indicating that our current understanding of the pathogenesis of MAC, a highly heterogeneous group of ocular defects, remains incomplete.

Confirmation of TENM3 involvement in autosomal recessive colobomatous microphthalmia.

Anophthalmia and microphthalmia are the most severe malformations of the eye, referring to a congenital absence, and a reduced size of the eyeball respectively. More than 20 genes have been shown to be mutated in patients with syndromic and non-syndromic forms of anophthalmia-microphthalmia. In a recent study combining autozygome and exome analysis, a homozygous loss of function mutation in TENM3 (previously named ODZ3) was reported in two siblings with isolated bilateral colobomatous microphthalmia from a consanguineous Saudi family. Herein, we report a third patient (not related to the previously reported family) with bilateral colobomatous microphthalmia and developmental delay in whom genetic studies identified a homozygous TENM3 splicing mutation c.2968-2A>T (p.Val990Cysfs*13). This report supports the association of TENM3 mutations with colobomatous microphthalmia and expands the phenotypic spectrum associated with mutations in this gene. © 2016 Wiley Periodicals, Inc.

Case report: Expansion of phenotypic and genotypic data in TENM3-related syndrome: Report of two cases.

Biallelic TENM3 variants were recently reported to cause non-syndromic microphthalmia with coloboma-9 (MCOPCB9) and microphthalmia and/or coloboma with developmental delay (MCOPS15). To date, only eight syndromic and non-syndromic microphthalmia cases with recessive TENM3 variants have been reported. Herein, we report two unrelated new cases with biallelic variants in TENM3, widening the molecular and clinical spectrum. Regarding patient 1, WES revealed compound heterozygous variants in the TENM3 gene: c.3847_3855del; p.Leu1283_Ser1285del and c.3698_3699insA; p.Thr1233Thrfs*20 in the index patient, who was presenting with bilateral microphthalmia, congenital cataract, microcephaly, and global developmental delay. Regarding patient 2, compound missense heterozygous variants in the TENM3 gene were identified: c.941C > T; p.Ala314Val and c.6464T > C; p.Leu2155Pro in the 3-year-old boy, who presented with congenital esotropia, speech delay, and motor developmental delay. The clinical features of these two cases revealed high concordance with the previously reported cases, including microphthalmia and developmental delay. The presence of microcephaly in our patient potentially expands the neurologic phenotype associated with loss of function variants in TENM3, as microcephaly has not previously been described. Furthermore, we present evidence that missense variants in TENM3 are associated with similar, but milder, ocular features.

Novel mutation in TENM3 gene in an Iranian patient with colobomatous microphthalmia.

This investigation revealed a homozygous c.5069-1G>C variation in TENM3 gene although has not been reported for its pathogenicity and can be considered as a novel mutation. The present finding can be used for genetic diagnosis and detection of carriers in the family and other patients with similar disease manifestations.

Microcornea, iris and choroidal coloboma, and global developmental delay caused by TENM3 pathogenic variants in a Chinese patient.

BACKGROUND: Biallelic TENM3 pathogenic variants cause isolated or syndromic microphthalmia. Syndromic microphthalmia 15 (MCOPS15) is characterized by microphthalmia, coloboma, and developmental delay. Currently, only four cases of MCOPS15 have been reported and the clinical features varied among the patients indicating potential broad phenotypic spectrum. METHODS: The present case was a 6-month-old male at diagnosis. The patient exhibited long philtrum, large ears, bilateral ptosis, and nystagmus. Ophthalmic tests showed that he had microcornea, iris and choroidal coloboma. The patient presented with global developmental delay (GDD). Trio-whole exome sequencing and genome copy number sequencing were conducted to explore the disease-causing mutations. RESULTS: Exome sequencing and genome copy number sequencing showed the presence of L1471F and E661G compound mutations in TENM3, which were inherited from the mother and father, respectively. Sanger sequencing was conducted to verify association of the mutations with the disease in the present family. CONCLUSION: Two TENM3 variants were identified in a patient with Syndromic microphthalmia 15 in the present study. However, further studies should be conducted to explore the pathogenicity of the variants.