How many entities exist for the spectrum of disorders associated with brachydactyly, syndactyly, short stature, microcephaly, and intellectual disability?

We describe a French young man with digital anomalies consisting of brachydactyly, F1-5 bilateral camptodactyly, interdigital webbing, F5 bilateral radial clinodactyly, and partial syndactyly of some fingers and toes. He had psychomotor retardation, short stature, umbilical hernia, a secundum atrial septal defect, seizures, hearing impairment, and dysmorphic features consisting of microcephaly, a prominent metopic ridge, upslanting palpebral fissures, synophrys, enophthalmia, large ears, a bulbous nose, a high palate, a smooth and short philtrum, a low hanging columella, a thin upper vermillion, an everted lower lip, prognathism, pectum excavatum, and supernumerary nipples. Osteotendinous reflexes were brisk. Mild nystagmus, myopia, and astigmatia were also noted. Total body X-rays showed short terminal phalanges of the hands, short middle phalanges of the index and little fingers, clinodactyly of the little fingers, short and fused proximal 4th and 5th metacarpals of the right hand, a short 5th metacarpal of the left hand, a fused left lunate-triquetrum, fused capitate-hamates, a prominent mandibula, and partial sacral agenesis. A thin posterior corpus callosum was apparent by MRI. Differential diagnoses for mainly the Rubinstein-Taybi syndrome, the Tsukahara syndrome, the Filippi syndrome, the Feingold syndrome, and the Tonoki syndrome are discussed, and the possibility that we might be reporting a novel entity is raised. © 2011 Wiley-Liss, Inc.

A novel PDE6D mutation in a patient with Joubert syndrome type 22 (JBTS22).

Joubert syndrome (JS) is an autosomal or X-linked recessive syndrome principally characterized by hypotonia, ataxia, cognitive impairment, and a specific finding on brain imaging called a "molar tooth sign" (MTS), which can be isolated or in conjunction with variable organ involvement. The genetic basis of JS is heterogeneous, with over 35 ciliary genes being implicated in its pathogenesis. However, some of these genes (such as PDE6D) have been associated to JS only in single families, seeking confirmation. Here we report a boy, born to first cousin parents, presenting with developmental delay, hypotonia, microcephaly, post axial polydactyly, oculomotor apraxia, and MTS. Whole exome sequencing revealed the presence of a novel homozygous truncating variant in the PDE6D gene: NM_002601.3:c.367_368insG [p.(Leu123Cysfs*13)]. The variant was confirmed by Sanger sequencing and found at the heterozygous state in both parents. A review of the literature pertaining to the role of PDE6D in JS is discussed.

Ceramide kinase targeting and activity determined by its N-terminal pleckstrin homology domain.

The N-terminus of ceramide kinase (CERK) is thought to be myristoylated and to contain a pleckstrin homology (PH) domain. We found that deletion of this region (DeltaPH-CERK) ablates activity. This is not due to prevention of N-terminal myristoylation since a G2A CERK mutant, which cannot be myristoylated, was active. CERK was able to bind liposomes, as well as the isolated unmyristoylated PH domain; DeltaPH-CERK was not. Upon analysis of EGFP-tagged proteins, CERK was found associated with the Golgi complex. Osmotic cell swelling induced translocation of CERK to the plasma membrane and formation of large vesicles displaying bound CERK. None of these features occurred with DeltaPH-CERK, which remained disseminated throughout the cytoplasm. These findings show that the PH domain of CERK is essential for localization, translocation, and activity of this lipid kinase.