Identification of KIF21A mutations as a rare cause of congenital fibrosis of the extraocular muscles type 3 (CFEOM3).

PURPOSE: Three congenital fibrosis of the extraocular muscles phenotypes (CFEOM1-3) have been identified. Each represents a specific form of paralytic strabismus characterized by congenital restrictive ophthalmoplegia, often with accompanying ptosis. It has been demonstrated that CFEOM1 results from mutations in KIF21A and CFEOM2 from mutations in PHOX2A. This study was conducted to determine the incidence of KIF21A and PHOX2A mutations among individuals with the third CFEOM phenotype, CFEOM3. METHODS: All pedigrees and sporadic individuals with CFEOM3 in the authors' database were identified, whether the pedigrees were linked or consistent with linkage to the FEOM1, FEOM2, and/or FEOM3 loci was determined, and the appropriate pedigrees and the sporadic individuals were screened for mutations in KIF21A and PHOX2A. RESULTS: Twelve CFEOM3 pedigrees and 10 CFEOM3 sporadic individuals were identified in the database. The structures of eight of the pedigrees permitted the generation of meaningful linkage data. KIF21A was screened in 17 probands, and mutations were identified in two CFEOM3 pedigrees. One pedigree harbored a novel mutation (2841G-->A, M947I) and one harbored the most common and recurrent of the CFEOM1 mutations identified previously (2860C-->T, R954W). None of CFEOM3 pedigrees or sporadic individuals harbored mutations in PHOX2A. CONCLUSIONS: The results demonstrate that KIF21A mutations are a rare cause of CFEOM3 and that KIF21A mutations can be nonpenetrant. Although KIF21A is the first gene to be associated with CFEOM3, the results imply that mutations in the unidentified FEOM3 gene are the more common cause of this phenotype.

Is vitamin D hypothesis for schizophrenia valid? Independent segregation of psychosis in a family with vitamin-D-dependent rickets type IIA.

The vitamin D hypothesis of schizophrenia is a recent concept bringing together old observations on environmental risk factors and new findings on the neurodevelopmental effects of vitamin D. Candidate genes related to the vitamin D endocrine system have not yet been fully explored for this purpose. The coexistence of vitamin-D-dependent-rickets type II with alopecia (VDDR IIA) and different forms of psychosis in the same inbred family has provided us with an opportunity to investigate the presumed relationship between vitamin D deficiency and psychosis. Psychiatric examination and molecular genetic studies were performed in this family overloaded with psychotic disorders and VDDR IIA. Forty members were evaluated in order to describe their phenotypic features. The family was tested for a linkage to the chromosome 12q12-q14 region where the vitamin D receptor (VDR) gene is located. Psychosis was the common phenotype in the 18 psychiatrically affected members. Pedigree analysis did not show a cosegregation of psychosis and rickets. Lod scores were not significant to prove a linkage between psychosis and VDR locus. The authors concluded that (1) the neurodevelopmental consequences of vitamin D deficiency do not play a causative role in psychotic disorders, (2) these two syndromes are inherited independently, and (3) vitamin D deficiency does not act as a risk factor in subjects susceptible to psychosis.

Heterozygous mutations of the kinesin KIF21A in congenital fibrosis of the extraocular muscles type 1 (CFEOM1).

Congenital fibrosis of the extraocular muscles type 1 (CFEOM1; OMIM #135700) is an autosomal dominant strabismus disorder associated with defects of the oculomotor nerve. We show that individuals with CFEOM1 harbor heterozygous missense mutations in a kinesin motor protein encoded by KIF21A. We identified six different mutations in 44 of 45 probands. The primary mutational hotspots are in the stalk domain, highlighting an important new role for KIF21A and its stalk in the formation of the oculomotor axis.

Hereditary intraosseous vascular malformation of the craniofacial region: an apparently novel disorder.

Primary intraosseous vascular anomaly, previously called intraosseous hemangioma, is a very rare malformation that is usually seen in the vertebral column and in the skull. It is exclusively described in sporadic cases and no hereditary component has yet been reported. The most commonly affected bones in the skull are the mandible and the maxilla, and life-threatening bleeding after a simple tooth extraction is frequently observed. Here, we report two consanguineous families containing a total of four affected patients manifesting primary intraosseous vascular malformation (VMOS (vascular malformation osseous)) of the craniofacial region. The phenotypic expression is remarkably similar in both families. The characteristic findings include severe blood vessel expansions within the craniofacial bones and midline abnormalities such as diastasis recti, supraumbilical raphe, and hiatus hernia. Malformation is restricted to the mandibular and maxillary area in the prepubertal age, and rapid expansion starts after age 12 or 13. A 15-year follow-up of one of the patients demonstrated that the vascular malformation did not extend beyond the craniofacial region despite severe involvement of almost all bones in the skull. Detailed clinical and radiological evaluation provided neither evidence of soft-tissue involvement nor any sign of gross arterial, venous, or combined malformations, indicating that bone changes are a primary rather than a secondary effect due to any other vascular anomaly in the craniofacial region. An antibody against a universal proliferation marker, Ki-67, detected nonproliferative, single-layered endothelial cells, suggesting that this abnormality is a vascular malformation rather than a hemangioma. alpha-actin staining (antibody against perivascular tissue such as smooth muscle cells (SMCs) and/or pericytes) demonstrated that pathologic vessels lost their surrounding supportive tissues, as was previously seen in other types of vascular anomaly. Homozygosity mapping excluded the following loci and/or genes: multiple cutaneous venous malformation (VMCM1; gene, TIE2) on chromosome 9p21; venous malformation with glomus cells (VMGLOM) on chromosome 1p22-p21; hereditary hemorrhagic telangiectasia type 1 (HHT1; gene, endoglin) and type 2 (HHT2; gene, activin) on chromosomes 9q34.1 and 12q11-q14, respectively; and cerebral cavernous malformation type 1 (CCM1; gene, KRIT1), type 2 (CCM2), and type 3 (CCM3) on chromosomes 7q11.2-q21, 7p15-p13, and 3q35.2-q27, respectively. To the best of our knowledge, this is a new disorder, which we call hereditary intraosseous vascular malformation of the craniofacial region.