Peters-Plus syndrome is a rare autosomal recessive disorder caused by biallelic pathogenic variants in the B3GLCT gene and characterized by multisystem involvement. Fewer than 100 cases have been reported to date, and only a limited number have been diagnosed prenatally. Prenatal identification is challenging due to the variable and non-specific nature of fetal findings and the frequent absence of detectable ocular anomalies during routine ultrasound. We report a prenatal diagnosis of Peters-Plus syndrome in a monochorionic diamniotic twin pregnancy, based on the progressive identification of early-onset intrauterine growth restriction, rhizomelic limb shortening, craniofacial dysmorphism, and mild central nervous system abnormalities. Standard cytogenetic and chromosomal microarray analyses were normal, prompting extended genetic testing. Prenatal exome sequencing identified a homozygous pathogenic splice-site variant (c.660+1G>A) in B3GLCT in both fetuses, confirming the diagnosis. This case highlights the importance of recognizing suggestive multisystem prenatal findings and the crucial role of advanced genetic testing in achieving an accurate prenatal diagnosis. Early molecular confirmation enables appropriate parental counseling regarding prognosis, recurrence risk, and future reproductive options.

Peters anomaly (PA) is a rare congenital disorder within the anterior segment dysgenesis (ASD) spectrum, characterized by corneal opacity, iridocorneal adhesions, and potential systemic involvement. The genetic basis of PA and related syndromes are complex and incompletely understood. This study investigates novel genetic variants and their clinical impact in two unrelated individuals diagnosed with PA spectrum disorder. Whole-exome sequencing (WES), long-range PCR, and breakpoint analysis were applied to identify pathogenic variants. In the first patient, a heterozygous ~1.6 Mb deletion was detected, spanning the genes PEX2 and ZFHX4 (GRCh37 chr8:g.76760782_78342600del). The second patient carried a heterozygous FOXC1 variant (NM_001453.3:c.310A>G), classified as likely pathogenic. Both variants were confirmed by Sanger sequencing and considered de novo, as they were not present in the biological parents. Clinical evaluations revealed phenotypic variability, with the first patient displaying both ocular and systemic anomalies as in a Peters plus-like syndrome phenotype, while the second patient had isolated ocular manifestations as in a PA type 1 phenotype. These findings expand the genetic landscape of PA, underscoring the importance of comprehensive genomic analysis in subclassifying ASD disorders. Further studies are needed to elucidate the functional consequences of these variants and improve diagnostic and therapeutic strategies.

To quantitatively analyze intraocular pressure (IOP) alongside clinical and morphometric findings in a cohort of children with Peters' anomaly (PA). This single-center retrospective study included a series of 46 children with PA. Glaucoma diagnosis in a subset was based on abnormal values of IOP, horizontal corneal diameter (HCD), or axial length (AL), individually or combined, compared to pediatric controls utilizing age-specific normative data. Patients were clinically classified into Peters I, II, III, and Peters-plus syndrome. Ultrasound biomicroscopy (UBM) was performed in 10 children. The cohort of 46 children comprised 27 males and 19 females. All presented with central discoid corneal opacities; 33 cases were bilateral, 13 unilateral. Clinical classifications included 26 Peters I, 10 Peters II, 7 Peters III, and 3 Peters-plus syndrome. In the 29 children analyzed for biometrics, the median age at diagnosis was 7 months (IQR: 1.00-21.00). Median AL was 20.84 mm (IQR: 19.36-22.47 mm) for OD and 20.19 mm (IQR: 18.67-24.05 mm) for OS. Median HCD was 11.5 mm (IQR: 10.50-12.50 mm) for OD and 11.5 mm (IQR: 10.50-13.00 mm) for OS. Glaucoma was diagnosed in 14 patients (48.3%). A significant increase in glaucoma prevalence was observed in children >6 months old (53.6%) compared to those 0-6 months old (26.7%) (p = 0.03). HCD and AL in PA often remain within normal limits, suggesting unique corneal biomechanics. Glaucoma in PA frequently manifests after 6 months of age, necessitating continuous monitoring.

Peters-Plus syndrome (PTRPLS) is an autosomal recessive congenital disorder of glycosylation caused by biallelic pathogenic variants in the ß 1,3-glucosyltransferase gene (B3GLCT). To date, homozygous or compound heterozygous splicing, truncating, missense variants, and whole gene deletions have been reported in the B3GLCT gene. Our aim was to investigate the role of small copy number variations (CNVs) in this condition alongside the clinical features of the patients. The study included eleven patients from six consanguineous families originating from the same village. Clinical exome sequencing-based CNV analysis was employed across all probands to ascertain the genetic background. Using GATK-gCNV, we identified a homozygous deletion on chromosome 13q12.3, encompassing the fifteenth exon of the B3GLCT gene. The median age at admission was 2.74 years, ranging from 2 months to 41 years. The mean standard deviation scores for height and weight at admission were -4.4±0.9 and -3.8±1.8, respectively. Ophthalmological abnormalities included corneal haze, anterior synechiae, unilateral leucoma, corneal-lenticular adhesion, glaucoma, and severe visual loss. Patients under the age of five years exhibited global developmental delay, while those older than five years demonstrated varying degrees of intellectual disability, with two exceptions exhibiting normal cognitive function. Our findings highlight an important role for Next-Generation Sequencing (NGS)-based CNV analysis in improving the diagnostic accuracy in PTRPLS. CNVs represent a significant form of genomic variation and should be systematically considered in genetically unresolved Mendelian disorders. Integrating CNV detection algorithms into routine NGS diagnostic workflows has the potential to enhance the identification of pathogenic changes, ultimately facilitating a more comprehensive molecular diagnosis for affected individuals. Peters plus syndrome is characterized by anterior chamber eye anomalies, short limbs with broad distal extremities, characteristic facial features, cleft lip/palate, and variable developmental delay / intellectual disability. The most common anterior chamber defect is Peters' anomaly, consisting of central corneal clouding, thinning of the posterior cornea, and iridocorneal adhesions. Cataracts and glaucoma are common. Developmental delay is observed in about 80% of children; intellectual disability can range from mild to severe. The diagnosis of Peters plus syndrome is a clinical diagnosis that can be confirmed by identification of biallelic B3GLCT pathogenic variants on molecular genetic testing. Treatment of manifestations: Consideration of corneal transplantation (penetrating keratoplasty) for severe bilateral corneal opacification before age three to six months to prevent amblyopia; consideration of simple separation of iridocorneal adhesions in mild cases; management of amblyopia by a pediatric ophthalmologist; surgical/medical intervention for glaucoma as needed; developmental/educational interventions as needed. Surveillance: Assessment by a pediatric ophthalmologist every three months in infancy and childhood or as indicated later on to monitor for glaucoma and amblyopia; regular developmental assessments. Agents/circumstances to avoid: Agents that increase risk of glaucoma (e.g., corticosteroids). Peters plus syndrome is inherited in an autosomal recessive manner. The parents of an affected child are obligate heterozygotes (i.e., carriers of one B3GLCT pathogenic variant). Heterozygotes (carriers) are asymptomatic. At conception, each sib of an affected individual has a 25% chance of being affected, a 50% chance of being an asymptomatic carrier, and a 25% chance of being unaffected and not a carrier. There is an increased chance for miscarriages and second- and third-trimester fetal loss of affected fetuses. Carrier testing for at-risk family members and prenatal diagnosis for pregnancies at increased risk are possible once the pathogenic variants have been identified in an affected family member.

Ventricular septal defects (VSDs) are recognized as one of the commonest congenital heart diseases (CHD), accounting for up to 40% of all cardiac malformations, and occur as isolated CHDs as well as together with other cardiac and extracardiac congenital malformations in individual patients and families. The genetic etiology of VSD is complex and extraordinarily heterogeneous. Chromosomal abnormalities such as aneuploidy and structural variations as well as rare point mutations in various genes have been reported to be associated with this cardiac defect. This includes both well-defined syndromes with known genetic cause (e.g., DiGeorge syndrome and Holt-Oram syndrome) and so far undefined syndromic forms characterized by unspecific symptoms. Mutations in genes encoding cardiac transcription factors (e.g., NKX2-5 and GATA4) and signaling molecules (e.g., CFC1) have been most frequently found in VSD cases. Moreover, new high-resolution methods such as comparative genomic hybridization enabled the discovery of a high number of different copy number variations, leading to gain or loss of chromosomal regions often containing multiple genes, in patients with VSD. In this chapter, we will describe the broad genetic heterogeneity observed in VSD patients considering recent advances in this field.