Expanding the Phenotype of the FAM149B1-Related Ciliopathy and Identification of Three Neurogenetic Disorders in a Single Family

Biallelic truncating FAM149B1 variants result in cilia dysfunction and have been reported in four infants with Joubert syndrome and orofaciodigital syndrome type VI, respectively. We report here on three adult siblings, 18 to 40 years of age, homozygous for the known FAM149B1 c.354_357delinsCACTC (p.Gln118Hisfs*20) variant. Detailed clinical examinations were performed including ocular and gait analyses, skeletal- and neuroimaging. All three patients presented with neurological and oculomotor symptoms since birth and mild skeletal dysplasia in infancy resulting in characteristic gait abnormalities. We document mild skeletal dysplasia, abnormal gait with increased hip rotation and increased external foot rotation, ataxia, variable polydactyly, ocular Duane syndrome, progressive ophthalmoplegia, nystagmus, situs inversus of the retinal vessels, olfactory bulb aplasia, and corpus callosal dysgenesis as novel features in FAM149B1-ciliopathy. We show that intellectual disability is mild to moderate and retinal, renal and liver function is normal in these affected adults. Our study thus expands the FAM149B1-related Joubert syndrome to a mainly neurological and skeletal ciliopathy phenotype with predominant oculomotor dysfunction but otherwise stable outcome in adults. Diagnosis of FAM149B1-related disorder was impeded by segregation of multiple neurogenetic disorders in the same family, highlighting the importance of extended clinical and genetic studies in families with complex phenotypes.

Foetal phenotype of Maat-Kievit-Brunner type Ohdo syndrome

MED12 is a member of large Mediator complex; has a very crucial and central role in RNA polymerase II transcription; regulating cell signals involved in growth, development and differentiation. Different MED12 mutations may have different clinical presentation representing an allelic disorder. Maat-Kievit-Brunner (MKB) type Ohdo syndrome; has a typical facial features comprising of blepharophimosis, ptosis, long flat philtrum with thin vermilion, micrognathia with microstomia, scrotal hypoplasia with cryptorchidism, joint hypermobility with clinodactyly with overriding toes, A primigravida on antenatal ultrasound was detected to have growth restriction, corpus callosal dysgenesis, syndactyly and suspected ambiguous genitalia. Invasive testing and exome sequencing revealed hg19chrX:MED12:c.2315A>G: (p.Lys772Arg);MED12(NM_005120.3):c.2315A>G: (p.Lys772Arg) leading to provisional diagnosis of X linked Ohdo syndrome with an overlap with FG. Missense mutation was classified to be PM2; PP3 (ACMG) Clinical presentation, phenotype and mutational analysis led to provisional diagnosis of X linked Ohdo syndrome. Maat-Kievit-Brunner type of Ohdo syndrome is a rare condition and this is probably the first case describing foetal phenotype of MKB type of Ohdo syndrome.

De Novo Partial 13q22-q34 Trisomy with Typical Neurological and Immunological Findings: A Case Report with New Genetic Insights

The partial trisomy 13q encompasses an extensive variability of phenotypic and radiological findings including leukoencephalopathy and brain malformations such as holoprosencephaly, callosal dysgenesis, hippocampal hypoplasia, olfactory hypoplasia, and vermian hypoplasia. We report for the first time a case of a 23-year-old patient affected by de novo partial 13q22.1q34 trisomy (41.7 Mb, 72,365,975-114,077,122x3) presenting with hemiparesis related to both ischemic and haemorrhagic cerebral lesions compatible with cerebral vasculitis due to a possible combination of genetic and immunological interaction.