Pontocerebellar hypoplasias (PCH) represent a group of neurodegenerative autosomal recessive disorders with prenatal onset, atrophy or hypoplasia of the cerebellum, hypoplasia of the ventral pons, microcephaly, variable neocortical atrophy and severe mental and motor impairments. In two subtypes, PCH2 and PCH4, we identified mutations in three of the four different subunits of the tRNA-splicing endonuclease complex. Our findings point to RNA processing as a new basic cellular impairment in neurological disorders.

Robinow syndrome is a short-limbed dwarfism characterized by abnormal morphogenesis of the face and external genitalia, and vertebral segmentation. The recessive form of Robinow syndrome (RRS; OMIM 268310), particularly frequent in Turkey, has a high incidence of abnormalities of the vertebral column such as hemivertebrae and rib fusions, which is not seen in the dominant form. Some patients have cardiac malformations or facial clefting. We have mapped a gene for RRS to 9q21-q23 in 11 families. Haplotype sharing was observed between three families from Turkey, which localized the gene to a 4. 9-cM interval. The gene ROR2, which encodes an orphan membrane-bound tyrosine kinase, maps to this region. Heterozygous (presumed gain of function) mutations in ROR2 were previously shown to cause dominant brachydactyly type B (BDB; ref. 7). In contrast, Ror2-/- mice have a short-limbed phenotype that is more reminiscent of the mesomelic shortening observed in RRS. We detected several homozygous ROR2 mutations in our cohort of RRS patients that are located upstream from those previously found in BDB. The ROR2 mutations present in RRS result in premature stop codons and predict nonfunctional proteins.

Cleidocranial Dysplasia (CCD) is an autosomal dominant skeletal disorder characterized by hypoplastic or absent clavicles, increased head circumference, large fontanels, dental anomalies, and short stature. Hand malformations are also common. Mutations in RUNX2 cause CCD, but are not identified in all CCD patients. In this study we screened 135 unrelated patients with the clinical diagnosis of CCD for RUNX2 mutations by sequencing analysis and demonstrated 82 mutations 48 of which were novel. By quantitative PCR we screened the remaining 53 unrelated patients for copy number variations in the RUNX2 gene. Heterozygous deletions of different size were identified in 13 patients, and a duplication of the exons 1 to 4 of the RUNX2 gene in one patient. Thus, heterozygous deletions or duplications affecting the RUNX2 gene may be present in about 10% of all patients with a clinical diagnosis of CCD which corresponds to 26% of individuals with normal results on sequencing analysis. We therefore suggest that screening for intragenic deletions and duplications by qPCR or MLPA should be considered for patients with CCD phenotype in whom DNA sequencing does not reveal a causative RUNX2 mutation.

Objective To investigate myo-inositol, glucose and zinc status in mothers and their infants on cleft lip with or without cleft palate risk (CLP). Design Case -control study. Setting University Medical Centre Nijmegen, the Netherlands. Population Eighty-four mothers and their CLP child and 102 mothers and their healthy child. Methods Venous blood samples were obtained to determine serum myo-inositol and glucose and red blood cell zinc concentrations in mothers and children. Geometric means were calculated and compared between the groups. The blood parameters were dichotomised with cutoff points based on control values, P90 for glucose concentrations. Main outcome measures Geometric means (P5 -P95) and odds ratios (95% confidence intervals). Results The CLP children (P ¼ 0.003) and their mothers (P ¼ 0.02) had significantly lower red blood cell zinc concentrations than controls. A low maternal serum myo-inositol concentration (<13.5 Amol/L) and a low red blood cell zinc concentration (<189 Amol/L) increased CLP risk [odds ratio 3.0 (95% CI 1.2 -7.4) and 2.0 (95% CI 0.8 -4.8), respectively]. Children with low myo-inositol (<21.5 Amol/L ) or low red blood cell zinc concentrations (<118 Amol/L) were more likely to have CLP [odds ratio 3.4 (95% CI 1.3-8.6) and 3.3 (95% CI 1.3 -8.0), respectively]. Glucose was not a risk factor for CLP in mothers and children. Maternal and child myo-inositol as well as zinc concentrations were slightly, albeit significantly correlated, r Pearson ¼ 0.33 (P ¼ 0.0006) and r Pearson ¼ 0.23 (P ¼ 0.01), respectively. Conclusion This study demonstrates for the first time that zinc and myo-inositol are important in the aetiology of CLP.

In patients with guanidinoacetate methyltransferase (GAMT) deficiency several parameters may point towards the diagnosis of GAMT deficiency. These include the low levels of creatine and creatinine in urine, the high concentration of guanidinoacetic acid (GAA) in urine and the low levels of creatine and creatinine in the cerebrospinal fluid (CSF). In this study, body fluids from 10 GAMT deficient patients were analysed using (1)H NMR spectroscopy. The urine 1D (1)H NMR spectra of all the patients showed a doublet resonance at 3.98 ppm (pH 2.50) derived from GAA present in high concentration. For this compound, a good recovery and good correlation was found between an LC-MS/MS method and (1)H NMR spectroscopy. In CSF NMR spectra of these patients, the singlet resonances of creatine and creatinine (3.05 and 3.13 ppm, respectively) were absent (normally always present in (1)H NMR spectra of CSF). Due to overlap by other resonances, the doublet of GAA could not be observed. Our data demonstrate that (1)H NMR spectroscopy of urine and CSF can be used to diagnose patients with GAMT deficiency.