Oculodentodigital Dysplasia: A Case Report and Major Review of the Eye and Ocular Adnexa Features of 295 Reported Cases

Oculodentodigital dysplasia (ODDD) is a rare genetic disorder associated with a characteristic craniofacial profile with variable dental, limb, eye, and ocular adnexa abnormalities. We performed an extensive literature review to highlight key eye features in patients with ODDD and report a new case of a female patient with a heterozygous missense GJA1 mutation (c.65G>A, p.G22E) and clinical features consistent with the condition. Our patient presented with multiple congenital anomalies including syndactyly, microphthalmia, microcornea, retrognathia, and a small nose with hypoplastic alae and prominent columella; in addition, an omphalocele defect was present, which has not been reported in previous cases. A systematic review of the published cases to date revealed 91 literature reports of 295 individuals with ODDD. There were 73 different GJA1 mutations associated with these cases, of which the most common were the following missense mutations: c.605G>A (p.R202H) (11%), c.389T>C (p.I130T) (10%), and c.119C>T (p.A40V) (10%). Mutations most commonly affect the extracellular-1 and cytoplasmic-1 domains of connexin-43 (gene product of GJA1), predominately manifesting in microphthalmia and microcornea. The syndrome appears with an approximately equal sex ratio. The most common eye features reported among all mutations were microcornea, microphthalmia, short palpebral fissures, and glaucoma.


Introduction
Oculodentodigital dysplasia (ODDD, OMIM #164200) is a rare disorder mainly characterized by abnormal craniofacial, dental, ocular, and digital development. The autosomal dominant form has been the most frequently reported inheritance pattern, although a few cases of autosomal recessive inheritance have been described [1][2][3]. Craniofacial abnormalities may include microcephaly, prominent columella, and underdeveloped nasal alae [2][3][4]. Dental abnormalities, such as hypoplastic enamel, small teeth, and premature loss of teeth, are often present [2][3][4]. Digit abnormalities may include syndactyly, camptodactyly, and midphalangeal hypoplasia [2][3][4]. Ophthalmic manifestations are common, such as microcornea and microphthalmia, and may involve a wide spectrum of eye and ocular adnexa structures, although previous analyses of prior cases show that full ocular physical exams were not performed on all patients [3,5].
The gap junction protein alpha 1 (GJA1) gene codes for connexin-43, which is a protein that assists in the transmembrane transport of molecules through gap junctions, and mutations in the GJA1 may cause an alteration of the channel conduction properties [1][2][3]6]. We report a case of an 8-month-old female patient with an identified GJA1 mutation and common clinical features associated with ODDD. This patient had an omphalocele at birth, which has not been reported in previous cases. Her eye features included microphthalmia, microcornea, narrow palpebral fissures, blonde fundus, deep anterior chambers, hyperopia, and epiphora in both eyes secondary to bilateral nasolacrimal duct obstructions. We conducted an extensive literature review to summarize the eye features in patients with ODDD reported to date.

Case Report
The patient, an 8-month-old female, was born to a nonconsanguineous couple from a healthy 37-year-old mother of Native American descent and a healthy 30-year-old father of German and Irish descent. Family history is notable for an older sibling with cleft palate, paternal uncle with autism, paternal second cousin with congenital heart defect, and distant paternal great-great uncle with Down syndrome and webbed/fused 4 th and 5 th digits of one hand. A normal pregnancy was noted until the second trimester when an omphalocele was detected on ultrasound. A subsequent ultrasound revealed possible syndactyly of the hands. The patient was born at 39 weeks by vaginal delivery with induction. The birth weight was 3.552 kg (75 th percentile), birth length was 50 cm (68 th percentile), and birth head circumference was 34.5 cm (70 th percentile). Apgar scores were 9 at both one minute and five minutes.
Multiple congenital anomalies noted at birth included an omphalocele that measured 4 cm at base and 3.5 cm across with intestines present in the sac, but no liver. The patient had a normocephalic head with sparse wispy hair, a small nose with hypoplastic alae, a prominent columella, smallappearing palpebral fissures, a small cornea, microphthalmia, a wide anterior fontanelle, and retrognathia ( Figure 1). Syndactyly of digits 4 and 5 and webbing of digits 3 and 4 of the right ( Figure 2) and left hands were present. Cardiac echocardiogram on the day of birth showed the presence of a mild patent ductus arteriosus, mild patent foramen ovale, and a normal aorta. Feeding difficulties were exacerbated by the presence of the omphalocele; surgical correction was performed on day 2 of life.
An ophthalmologic assessment at 4 months of age was notable for deep anterior chambers, bilateral nasolacrimal duct obstruction, microphthalmia, small 8 mm corneas, a blonde fundus, and moderate hyperopia in both eyes.
At her last examination at 8 months of age, the patient continues to have poor feeding with self-limiting volumes but has improved weight gain. The patient is at the 9 th percentile for weight and 12 th percentile for length. Cognitive and motor developments are delayed.
Sequencing of the GJA1 gene (transcript number: NM_ 000165.3) from patient genomic DNA revealed a heterozygous missense mutation in the GJA1 gene: c.65G>A (p.G22E). Deletion/duplication analysis of the GJA1 gene using the aCGH test was negative.

Methods
We performed a systematic review of the literature to summarize the ocular findings in individuals with ODDD. A PubMed/Medline search of "oculodentodigital syndrome" led us to find a total of 177 articles. No articles were excluded based on the year published. We reviewed the references to identify other articles that did not appear in our original search. 91 articles describing patients with a description consistent with the clinical syndrome, either with or without molecular confirmation of GJA1 pathogenic variants, were included. Within these selected articles, we identified 295 cases of ODDD with 73 different GJA1 mutations, including   Case Reports in Ophthalmological Medicine those that exhibited features of ODDD in the absence of molecular confirmation. Such individuals were either clinically diagnosed or were relatives of individuals with molecularly confirmed GJA1 pathogenic variants. Twelve reported that GJA1 gene coding alterations were omitted due to insufficient clinical information and data reported and are listed in Table 1 [3,6].

Discussion
Oculodentodigital dysplasia (ODDD) is a rare congenital disorder manifested with developmental anomalies of the eyes, face, dentition, heart, skeletal system, and digits. The syndrome appears to be more common in Caucasian populations with an equal sex ratio [3]. Heterozygous mutation of the GJA1 gene located at chromosome 6q22.31 has been identified as the most common mutation resulting in ODDD [2,3]. However, a compound heterozygous individual with missense mutations demonstrated mutations in the GJA1 gene (p.V41L) and the GJB2 gene (p.R127H), which encode for connexin-43 and connexin-26, respectively, and has been reported and classified as having overlapping features of Clouston syndrome and ODDD [3,7]. In addition to the classic phenotypic features of the syndrome, a wide variety of additional physical manifestations have been observed. Ocular findings of microphthalmia and microcornea have been observed commonly in previous cases [2][3][4]. Craniofacial anomalies of microcephaly, poor hair growth, hypoplastic nasal alae, and prominent columella have been reported previously [2][3][4]. Bilateral syndactyly of the 4 th and 5 th digits is common [2,3].
A systematic review of the published cases to date (ranging from 1963 to 2019) revealed 91 literature reports of 295 individuals with ODDD . Table 2   summarizes the sex distribution across all reviewed reports of ODDD. Patients with ODDD present with an approximately equal sex distribution (47% male and 53% female). Of the 295 individuals reported, 32 were clinically diagnosed with ODDD without molecular confirmation, 98 presented with features of ODDD and had a known relative with molecular confirmation of a GJA1 pathogenic variant, and 165 individuals had a molecularly confirmed GJA1 pathogenic variant.
There were 73 different GJA1 mutations identified from the 165 individuals that had a molecularly confirmed GJA1 pathogenic variant. Table 3 [1-3, 5-71, 92] summarizes the number of patients with each mutation. Patients with confirmed pathogenic variants and their relatives with no molecular confirmation but with features of ODDD were grouped separately. These two groups comprised 263 of the patients included in this study.
A variety of abnormal findings for the retina and optic disc were noted (n = 18), with dysplasia of the retina/fundus (n = 3) and pale/atrophic optic discs (n = 3) being the most common documented findings.
Some unique genotype-phenotype correlations were noted upon further analysis. Three patients presented with eccentric pupils, but only 2 of these patients were reported with an associated mutation. Both mutations (p.Q49dup and p.Q49P) seem to affect the same amino acid in connexin-43 [3,61,72]. Additionally, uveitis was reported in 10 patients, 9 of which were associated with similar mutations. Eight of these patients were within the same study and had the p.H194P mutation, another patient had no molecular confirmation of a GJA1 mutation, and the other patient was reported with a missense mutation on exon 2 [4,9,10,27,28]. However, since the majority of these patients were reported within the same study, the apparent genotype-phenotype correlation of p.H194P and uveitis might be due to underreporting of uveitis from other sources with different pathogenic variants or may be due to other factors of the family not identified within the study.
Further analysis of the genotype-phenotype correlation was conducted by pairing the phenotypic manifestations of each mutation with the corresponding defects in the connexin-43 domains. The domains were defined by the amino acid ranges provided on UniProt (P17302-CXA1_ HUMAN) [93]. Table 6 [1-3, 5-71, 92, 93] provides a summary of the phenotypes associated with mutations from each domain.
The domains most commonly affected by GJA1 mutations are the extracellular-1 loop and the cytoplasmic-1 loop of connexin-43, accounting for 19 and 20 mutations, respectively. Disruptions in the extracellular-1 loop presented primarily as microphthalmia (n = 32) and microcornea (n = 30). A similar pattern can be seen in the cytoplasmic-1 loop, as the most common presentations were microphthalmia (n = 20) and microcornea (n = 18). Other clinical findings, however, may be able to distinguish mutations resulting from these domains. The next most common findings associated with mutations in the extracellular-1 loop were glaucoma (n = 15) and hypertelorism (n = 11), as opposed to short palpebral fissures (n = 14) and hypotelorism (n = 14) for the cytoplasmic-1 loop.
Mutations affecting the cytoplasmic N-terminus and the transmembrane-1 domain shared similar features to the ones in the extracellular-1 and cytoplasmic-1 domains, as microphthalmia and microcornea were the most common clinical findings. However, the mutations in the cytoplasmic N-terminus and transmembrane-1 domain presented with microcornea (n = 17 and n = 21, respectively) more frequently than microphthalmia (n = 5 and n = 14, respectively). The opposite pattern is true for the extracellular-1 and cytoplasmic-1 domains.

Conflicts of Interest
Virang Kumar and Arti Pandya declare that they have no conflicts of interest. Natario L. Couser, MD, MS, is a principal investigator at the Virginia Commonwealth University site of Retrophin, Inc., and book editor in Elsevier.

Supplementary Materials
Supplementary Material 1: all GJA1 mutations with associated eye and ocular adnexa features. This dataset groups patients with ODDD by GJA1 mutation and reports the associated eye and ocular adnexa features. (Supplementary  Materials)