Mutations in the RECQL4 gene can lead to three clinical phenotypes with overlapping features. All these syndromes, Rothmund-Thomson (RTS), RAPADILINO and Baller-Gerold (BGS), are characterized by growth retardation and radial defects, but RAPADILINO syndrome lacks the main dermal manifestation, poikiloderma that is a hallmark feature in both RTS and BGS. It has been previously shown that RTS patients with RECQL4 mutations are at increased risk of osteosarcoma, but the precise incidence of cancer in RAPADILINO and BGS has not been determined. Here, we report that RAPADILINO patients identified as carriers of the c.1390 þ 2delT mutation (p.Ala420_Ala463del) are at increased risk to develop lymphoma or osteosarcoma (6 out of 15 patients). We also summarize all the published RECQL4 mutations and their associated cancer cases and provide an update of 14 novel RECQL4 mutations with accompanying clinical data.

Mutations in FOXP2 cause developmental verbal dyspraxia (DVD), but only a few cases have been described. We characterize 13 patients with DVD--5 with hemizygous paternal deletions spanning the FOXP2 gene, 1 with a translocation interrupting FOXP2, and the remaining 7 with maternal uniparental disomy of chromosome 7 (UPD7), who were also given a diagnosis of Silver-Russell Syndrome (SRS). Of these individuals with DVD, all 12 for whom parental DNA was available showed absence of a paternal copy of FOXP2. Five other individuals with deletions of paternally inherited FOXP2 but with incomplete clinical information or phenotypes too complex to properly assess are also described. Four of the patients with DVD also meet criteria for autism spectrum disorder. Individuals with paternal UPD7 or with partial maternal UPD7 or deletion starting downstream of FOXP2 do not have DVD. Using quantitative real-time polymerase chain reaction, we show the maternally inherited FOXP2 to be comparatively underexpressed. Our results indicate that absence of paternal FOXP2 is the cause of DVD in patients with SRS with maternal UPD7. The data also point to a role for differential parent-of-origin expression of FOXP2 in human speech development.

Mulibrey nanism (for muscle-liver-brain-eye nanism, MUL; MIM 253250) is an autosomal recessive disorder that involves several tissues of mesodermal origin, implying a defect in a highly pleiotropic gene. Characteristic features include severe growth failure of prenatal onset and constrictive pericardium with consequent hepatomegaly. In addition, muscle hypotonia, J-shaped sella turcica, yellowish dots in the ocular fundi, typical dysmorphic features and hypoplasia of various endocrine glands causing hormonal deficiency are common. About 4% of MUL patients develop Wilms' tumour. MUL is enriched in the Finnish population, but is rare elsewhere. We previously assigned MUL to chromosome 17q22-q23 and constructed a physical contig over the critical MUL region. The region has now been further refined by haplotype analysis and new positional candidate genes have been localized. We identified a gene with four independent MUL-associated mutations that all cause a frameshift and predict a truncated protein. MUL is ubiquitously expressed and encodes a new member of the RING-B-box-Coiled-coil (RBCC) family of zinc-finger proteins, whose members are involved in diverse cellular functions such as developmental patterning and oncogenesis.

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Maternal uniparental disomy of chromosome 7 (matUPD7), the inheritance of both chromosomes from only the mother, is observed in approximately 10% of patients with Silver-Russell syndrome (SRS). It has been suggested that at least one imprinted gene that regulates growth and development resides on human chromosome 7. To date, three imprinted genes-PEG1/MEST, gamma2-COP, and GRB10-have been identified on chromosome 7, but their role in the etiology of SRS remains uncertain. In a systematic screening with microsatellite markers, for matUPD7 cases among patients with SRS, we identified a patient who had a small segment of matUPD7 and biparental inheritance of the remainder of chromosome 7. Such a pattern may be explained by somatic recombination in the zygote. The matUPD7 segment at 7q31-qter extends for 35 Mb and includes the imprinted gene cluster of PEG1/MEST and gamma2-COP at 7q32. GRB10 at 7p11.2-p12 is located within a region of biparental inheritance. Although partial UPD has previously been reported for chromosomes 6, 11, 14, and 15, this is the first report of a patient with SRS who has segmental matUPD7. Our findings delimit a candidate imprinted region sufficient to cause SRS.

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BackgroundThe salivary α-amylase locus (AMY1) is located in a highly polymorphic multi allelic copy number variable chromosomal region. A recent report identified an association between AMY1 copy numbers and BMI in common obesity. The present study investigated the relationship between AMY1 copy number, BMI and serum amylase in childhood-onset obesity.PatientsSixty-one subjects with a history of childhood-onset obesity (mean age 19.1 years, 54% males) and 71 matched controls (19.8 yrs, 45% males) were included. All anthropometric measures were greater in the obese; their mean BMI was 40 kg/m2 (range 25-62 kg/m2) compared with 23 kg/m2 in the controls (15-32 kg/m2).ResultsMean AMY1 copy numbers did not differ between the obese and control subjects, but gender differences were observed; obese men showed the highest and obese women the lowest number of AMY1 copies (p=0.045). Further, only in affected females, AMY1 copy number correlated significantly with whole body fat percent (r=-0.512, p=0.013) and BMI (r=-0.416, p=0.025). Finally, a clear linear association between AMY1 copy number and serum salivary amylase was observed in all subgroups but again differences existed between obese males and females.ConclusionsIn conclusion, our findings suggest that AMY1 copy number differences play a role in childhood-onset obesity but the effect differs between males and females. Further studies in larger cohorts are needed to confirm these observations.

Mulibrey nanism is a rare growth disorder of prenatal onset caused by mutations in the TRIM37 gene, which encodes a RING-B-box-coiled-coil protein. The pathogenetic mechanisms of mulibrey nanism are unknown. We have used transiently transfected cells and antibodies raised against the predicted TRIM37 protein to characterize the TRIM37 gene product and to determine its intracellular localization. We show that the human TRIM37 cDNA encodes a peroxisomal protein with an apparent molecular weight of 130 kD. Peroxisomal localization is compromised in mutant protein representing the major Finnish TRIM37 mutation but is retained in the protein representing the minor Finnish mutation. Colocalization of endogenous TRIM37 with peroxisomal markers was observed by double immunofluorescence staining in HepG2 and human intestinal smooth muscle cell lines. In human tissue sections, TRIM37 shows a granular cytoplasmic pattern. Endogenous TRIM37 is not imported into peroxisomes in peroxin 1 (PEX1(-/-)) and peroxin 5 (PEX5(-/-)) mutant fibroblasts but is imported normally in peroxin 7 (PEX7(-/-)) deficient fibroblasts, giving further evidence for a peroxisomal localization of TRIM37. Fibroblasts derived from patients with mulibrey nanism lack C-terminal TRIM37 immunoreactivity but stain normally for both peroxisomal matrix and membrane markers, suggesting apparently normal peroxisome biogenesis in patient fibroblasts. Taken together, this molecular evidence unequivocally indicates that TRIM37 is located in the peroxisomes, and Mulibrey nanism thus can be classified as a new peroxisomal disorder.