Kaufman oculocerebrofacial syndrome (KOS; OMIM #244450)is a rare autosomal recessive disorder caused by pathogenic biallelic variants in UBE3B, characterized by craniofacial dysmorphism, global developmental delay, hypotonia, and multisystem anomalies. We describe a 12-month-old Jordanian girl born to consanguineous parents, who exhibited microcephaly, hypotonia, feeding difficulties, and failure to thrive. Echocardiography revealed a mild basal septal hypertrophy. Developmental evaluation confirmed moderate global delay. Whole-exome sequencing revealed a homozygous UBE3B splice site variant (c.1741 + 2T > C), previously reported as pathogenic in ClinVar and classified as pathogenic according to ACMG/AMP criteria but without a detailed phenotypic description. Family history revealed additional neonatal deaths in a consanguineous context, raising the possibility of an underlying autosomal recessive condition. This case adds to the limited body of literature on KOS and provides further evidence for the pathogenicity of the c.1741 + 2T > C variant. This case highlights the importance of considering KOS in infants presenting with characteristic craniofacial features such as blepharophimosis, ptosis, preauricular tags, and developmental delay, particularly in consanguineous families.

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.

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.

Kaufman oculocerebrofacial syndrome (KOS) is an autosomal recessive developmental disorder. Inactivating mutations in UBE3B, an E3 ubiquitin ligase gene are causative for KOS. We have reported that towards postnatal week three, its murine ortholog, Ube3b, acts as a negative regulator of the number of dendritic spines. In this study, we investigated the role of Ube3b at the synapse in the young adult mice. With an improved estimation method, images from the hippocampal CA1 and CA2 regions acquired with 3D Stimulated Emission Depletion (3D-STED) microscopy were used to quantify the excitatory synapse numbers. In the young adult mice, the excitatory synapse density was decreased in brain-specific Ube3b conditional knockout mice as compared to the control. Our results indicate the novel role of Ube3b in the maintenance of synapse numbers in the young adult period.

Kaufman oculocerebrofacial syndrome (KOS) is characterized by developmental delay, severe intellectual disability, and distinctive craniofacial features. Most affected children have prenatal-onset microcephaly, hypotonia, and growth deficiency. Feeding issues, ocular abnormalities, hearing impairment, and respiratory tract abnormalities are common. Ocular abnormalities can include structural abnormalities (microcornea or microphthalmia, coloboma, optic nerve hypoplasia), refractive errors (myopia ± astigmatism, hyperopia), strabismus, and entropion. Both conductive and sensorineural hearing loss have been reported as well as mixed conductive-sensorineural hearing loss of variable severity. Breathing problems can lead to prolonged hospitalization after birth in more than half of individuals. Less common findings include ectodermal abnormalities, cardiac manifestations, urogenital abnormalities, seizures, and skeletal abnormalities. The diagnosis of KOS is established in a proband with developmental delay/intellectual disability and biallelic UBE3B pathogenic variants. Treatment of manifestations: Educational intervention and speech therapy beginning in infancy; standard treatment with anti-seizure medication in those with seizures; early intervention as needed for feeding problems and respiratory problems; routine management of ophthalmologic issues, hearing impairment, congenital heart defects, urogenital abnormalities, and skeletal abnormalities. Surveillance: At least annual assessment of developmental progress, growth, vision, and hearing. Assess for seizures and respiratory issues at each visit. At least annual examination for contractures and scoliosis. KOS is inherited in an autosomal recessive manner. If both parents are known to be heterozygous for a UBE3B pathogenic variant, each sib of an affected individual has at conception a 25% chance of being affected, a 50% chance of being an asymptomatic carrier, and a 25% chance of inheriting neither of the familial pathogenic variants. Once the UBE3B pathogenic variants have been identified in an affected family member, carrier testing for at-risk relatives, prenatal testing for a pregnancy at increased risk, and preimplantation genetic testing are possible.