Yanick Crow and colleagues show that mutations in ACP5, which encodes tartrate-resistant acid phosphatase, cause spondyloenchondrodysplasia, a bone dysplasia with autoimmunity. The affected individuals had elevated serum interferon alpha activity. We studied ten individuals from eight families showing features consistent with the immuno-osseous dysplasia spondyloenchondrodysplasia. Of particular note was the diverse spectrum of autoimmune phenotypes observed in these individuals (cases), including systemic lupus erythematosus, Sjögren's syndrome, hemolytic anemia, thrombocytopenia, hypothyroidism, inflammatory myositis, Raynaud's disease and vitiligo. Haplotype data indicated the disease gene to be on chromosome 19p13, and linkage analysis yielded a combined multipoint log10 odds (LOD) score of 3.6. Sequencing of ACP5, encoding tartrate-resistant acid phosphatase, identified biallelic mutations in each of the cases studied, and in vivo testing confirmed a loss of expressed protein. All eight cases assayed showed elevated serum interferon alpha activity, and gene expression profiling in whole blood defined a type I interferon signature. Our findings reveal a previously unrecognized link between tartrate-resistant acid phosphatase activity and interferon metabolism and highlight the importance of type I interferon in the genesis of autoimmunity.

Klippel-Feil syndrome (KFS) is a congenital disorder of spinal segmentation distinguished by the bony fusion of anterior/cervical vertebrae. Scoliosis, mirror movements, otolaryngological, kidney, ocular, cranial, limb, and/or digit anomalies are often associated. Here we report mutations at the GDF6 gene locus in familial and sporadic cases of KFS including the recurrent missense mutation of an extremely conserved residue c.866T>C (p.Leu289Pro) in association with mirror movements and an inversion breakpoint downstream of the gene in association with carpal, tarsal, and vertebral fusions. GDF6 is expressed at the boundaries of the developing carpals, tarsals, and vertebrae and within the adult vertebral disc. GDF6 knockout mice are best distinguished by fusion of carpals and tarsals and GDF6 knockdown in Xenopus results in a high incidence of anterior axial defects consistent with a role for GDF6 in the etiology, diversity, and variability of KFS. Hum Mutat 0,1–11, 2008.

Oculofaciocardiodental (OFCD) and Lenz microphthalmia syndromes form part of a spectrum of X-linked microphthalmia disorders characterized by ocular, dental, cardiac and skeletal anomalies and mental retardation. The two syndromes are allelic, caused by mutations in the BCL-6 corepressor gene (BCOR). To extend the series of phenotypes associated with pathogenic mutations in BCOR, we sequenced the BCOR gene in patients with (1) OFCD syndrome, (2) putative X-linked (‘Lenz’) microphthalmia syndrome, (3) isolated ocular defects and (4) laterality phenotypes. We present a new cohort of females with OFCD syndrome and null mutations in BCOR, supporting the hypothesis that BCOR is the sole molecular cause of this syndrome. We identify for the first time mosaic BCOR mutations in two females with OFCD syndrome and one apparently asymptomatic female. We present a female diagnosed with isolated ocular defects and identify minor features of OFCD syndrome, suggesting that OFCD syndrome may be mild and underdiagnosed. We have sequenced a cohort of males diagnosed with putative X-linked microphthalmia and found a mutation, p.P85L, in a single case, suggesting that BCOR mutations are not a major cause of X-linked microphthalmia in males. The absence of BCOR mutations in a panel of patients with non-specific laterality defects suggests that mutations in BCOR are not a major cause of isolated heart and laterality defects. Phenotypic analysis of OFCD and Lenz microphthalmia syndromes shows that in addition to the standard diagnostic criteria of congenital cataract, microphthalmia and radiculomegaly, patients should be examined for skeletal defects, particularly radioulnar synostosis, and cardiac/laterality defects.