A novel WTX mutation in a female patient with osteopathia striata with cranial sclerosis and hepatoblastoma.

Osteopathia striata with cranial sclerosis (OSCS) is an X-linked dominant sclerosing bone dysplasia. Typically affected females show macrocephaly, characteristic facial appearance, cleft palate, mild learning difficulties, hearing loss, sclerosis of the long bones and skull, and longitudinal striations visible on radiographs of the long bones, pelvis and scapulae. Typically affected males usually die at the fetal or early neonatal stage. Because of its variable expressivity, which ranges from asymptomatic to fetal death, clinical diagnosis of OSCS can be difficult. Here, we identify a unique female patient presenting with severe macrocephaly, characteristic facial appearance, developmental delay, and hepatoblastoma. Exome sequencing identified a novel de novo nonsense mutation (c.1045C>T, p.Glu349*) in the WTX gene associated with OSCS. The OSCS diagnosis was confirmed in this patient based on the hallmark appearance of longitudinal striations in long bones when viewed by X-ray. WTX is also known as a tumor suppressor gene, and somatic mutations in that gene have been identified in Wilms tumors. In addition to this patient, although two patients with OSCS have been reported to have colorectal cancer or ovarian cancer, Wilms tumor has never been reported in association with this disorder. Tumor susceptibility in patients with OSCS is discussed.

Co-occurrence of 22q11 deletion syndrome and HDR syndrome.

22q11 deletion syndrome is one of the most common chromosomal deletion syndromes and is usually caused by a 1.5-3.0 Mb deletion at chromosome 22q11.2. It is characterized by hypocalcemia resulting from hypoplasia of the parathyroid glands, hypoplasia of the thymus, and defects of the cardiac outflow tract. We encountered a Japanese boy presenting with an unusually severe phenotype of 22q11 deletion syndrome, including progressive renal failure and severe intellectual disabilities. Diagnostic testing using fluorescent in situ hybridization revealed deletion of the 22q11 region, but this did not explain the additional complications. Copy number analysis was therefore performed using whole genome single nucleotide polymorphism (SNP) assay, which identified an additional de novo deletion at 10p14. This region is the locus for hypoparathyroidism, deafness, and renal dysplasia (HDR) syndrome caused by haploinsufficiency of GATA3. Together, these two syndromes sufficiently explain the patient's phenotype. This is the first known case report of the co-occurrence of 22q11 deletion syndrome and HDR syndrome. As the two syndromes overlap clinically, this study indicates the importance of carrying out careful clinical and genetic assessment of patients with atypical clinical phenotypes or unique complications. Unbiased genetic analysis using whole genome copy number SNP arrays is especially useful for detecting such rare double mutations.

MLL2 and KDM6A mutations in patients with Kabuki syndrome.

Kabuki syndrome is a congenital anomaly syndrome characterized by developmental delay, intellectual disability, specific facial features including long palpebral fissures and ectropion of the lateral third of the lower eyelids, prominent digit pads, and skeletal and visceral abnormalities. Mutations in MLL2 and KDM6A cause Kabuki syndrome. We screened 81 individuals with Kabuki syndrome for mutations in these genes by conventional methods (n = 58) and/or targeted resequencing (n = 45) or whole exome sequencing (n = 5). We identified a mutation in MLL2 or KDM6A in 50 (61.7%) and 5 (6.2%) cases, respectively. Thirty-five MLL2 mutations and two KDM6A mutations were novel. Non-protein truncating-type MLL2 mutations were mainly located around functional domains, while truncating-type mutations were scattered through the entire coding region. The facial features of patients in the MLL2 truncating-type mutation group were typical based on those of the 10 originally reported patients with Kabuki syndrome; those of the other groups were less typical. High arched eyebrows, short fifth finger, and hypotonia in infancy were more frequent in the MLL2 mutation group than in the KDM6A mutation group. Short stature and postnatal growth retardation were observed in all individuals with KDM6A mutations, but in only half of the group with MLL2 mutations.

Fluoro-Jade: new fluorescent marker of Rosenthal fibers.

Rosenthal fibers are homogeneous eosinophilic masses found in astrocytes that are composed of glial fibrillary acidic protein (GFAP) aggregates along with chaperone proteins and other unknown components. Rosenthal fiber formation is a pathological hallmark of Alexander disease and its detection is diagnostically significant. However, the lack of a specific fluorescent marker has greatly limited the histochemical characterization of Rosenthal fibers. Here, we report for the first time a fluorescent marker of Rosenthal fibers called Fluoro Jade. Fluoro Jade-positive masses were seen in samples of Alexander disease brain, pilocytic astrocytoma, and in brain tissue from a mouse model of Alexander disease. Fluoro Jade co-labeled tissue samples stained with GFAP immunofluorescence. Our results indicated that Fluoro Jade labeled Rosenthal fibers, and that Rosenthal fibers could be labeled with antibodies of interest in combination with Fluoro Jade staining.