Further phenotypic characterization of Kaufman oculocerebrofacial syndrome: report of five new cases and literature review

Novel UBE3B mutations: report of eight patients with Kaufman oculocerebrofacial syndrome with additional clinical findings from a highly consanguineous population

Biallelic mutations in UBE3B cause Kaufman oculocerebrofacial syndrome (KOS; OMIM 244450) with a wide range of clinical manifestations. In this study, we employed genetic analyses including homozygosity mapping, candidate gene sequencing, whole exome sequencing, and confirmatory Sanger sequencing on eight patients from three unrelated consanguineous families. Our analysis yielded three different novel variants in UBE3B : a missense substitution [NM_130466.4: c.2975C>T; (p.Pro992Leu)] in the HECT domain in family 1, a 3-bp deletion within exon 14 [c.1692_1694delCTC; (p.Ser565del)] leading to removal of a serine residue in family 2, and a splice donor site variant in intron eight of UBE3B (c.630 + 1G>T) in family 3. Blepharophimosis, telecanthus, ptosis, intellectual disability and abnormal lipid profile were similar to those found in previously reported KOS patients. Longitudinal follow-up revealed rather marfanoid body habitus of the patients in family 1. This study reports eight patients from Saudi Arabia with novel deleterious variants in UBE3B and adds to the phenotypic spectrum of KOS.

Whole Exome Sequencing Achieved a Definite Diagnosis of Kaufman Oculocerebrofacial Syndrome in a Bahraini Family: A Case Report

A 1 year and 7 months old girl presented to the medical genetic clinic as a referral from the pediatrics clinic. Upon examining the patient and assessing past medical history, an autosomal recessive disorder was suspected. The family underwent whole exome sequencing, which resulted in the diagnosis of Kaufman oculocerebrofacial syndrome (OMIM #244450) in the patient due to the fact that both parents were heterozygous carriers of a novel pathogenic variant in the gene UBE3B that lies on 12q24. It has been recommended for the family that preimplantation genetic testing should be considered for future pregnancies. In this case report, we present a novel variant of the gene and highlight the support of whole exome sequencing in the unveiling of genetic disorders.

Two Siblings with Kaufman Oculocerebrofacial Syndrome Resembling Oculoauriculovertebral Spectrum

Kaufman oculocerebrofacial syndrome is a rare autosomal recessive disorder which represents a phenotype mainly involving craniofacial and neurodevelopmental manifestations due to UBE3B gene mutations. The vast majority of the affected individuals exhibit microcephaly, eye abnormalities, and typical facial gestalt including blepharophimosis, ptosis, telecanthus, upslanting palpebral fissures, dysplastic ears, and micrognathia. We encountered 2 siblings in whom severe psychomotor delay, distinctive facial features, hearing loss, and respiratory distress were observed. Some clinical manifestations of the patients, including epibulbar dermoid, microtia, and multiple preauricular tags, were reminiscent of the oculoauriculovertebral spectrum. However, 2 affected siblings exhibited a similar clinical picture consisting of microcephaly, severe developmental and cognitive disabilities, failure to thrive, and dysmorphic features, which were not fully consistent with oculoauriculovertebral spectrum. Also, hypoplastic nails, considered as a core manifestation of Coffin-Siris syndrome, were present in our patients. Therefore, whole-exome sequencing was carried out in order to identify the underlying genetic alterations, contributing to the complex phenotype shared by the 2 siblings. A homozygous pathogenic mutation was found in both affected siblings in the UBE3B gene which caused Kaufman oculocerebrofacial syndrome. Kaufman oculocerebrofacial syndrome should be considered among the autosomal recessive causes of blepharophimosis-mental retardation syndromes, particularly in populations with a high rate of consanguineous marriages, even if there are dysmorphic facial features that are not typically associated with the phenotype.

Blepharophimosis-ptosis-intellectual disability syndrome: A report of nine Egyptian patients with further expansion of phenotypic and mutational spectrum

Blepharophimosis-ptosis-intellectual disability syndrome (BPID) is an extremely rare recognizable blepharophimosis intellectual disability syndrome (BID). It is caused by biallelic variants in the UBE3B gene with only 24 patients described worldwide. Herein, we report on the clinical, brain imaging and molecular findings of additional nine patients from six unrelated Egyptian families. Patients presented with the characteristic features of the syndrome including blepharophimosis, ptosis, upslanted palpebral fissures with epicanthic folds, hypertelorism, long philtrum, high arched palate, micrognathia, microcephaly, and intellectual disability. Other findings were congenital heart disease (5 patients), talipes equinovarus (5 patients), genital anomalies (5 patients), autistic features (4 patients), cleft palate (2 patients), hearing loss (2 patients), and renal anomalies (1 patient). New or rarely reported findings were spherophakia, subvalvular aortic stenosis and hypoplastic nails, and terminal phalanges. Brain MRI, performed for 7 patients, showed hypogenesis or almost complete agenesis of corpus callosum. Genetic studies revealed five novel homozygous UBE3B variants. Of them, the c.1076G>A (p.W359*) was found in three patients from two unrelated families who shared similar haplotype suggesting a likely founder effect. Our results strengthen the clinical, dysmorphic, and brain imaging characteristic of this unique type of BID and extend the mutational spectrum associated with the disorder.