Trilateral retinoblastoma in a patient with Peutz-Jeghers syndrome.

Germline loss of function mutations in tumor suppressor genes RB1 and LKB1/STK11 are associated with the autosomal dominant cancer predisposing syndromes familial retinoblastoma and Peutz-Jeghers syndrome (PJS), respectively. We present a rare case of a young woman with trilateral retinoblastoma diagnosed as an infant who survived and was then diagnosed with PJS as a teenager. There was no family history of either disorder. Analysis of the LKB1/STK11 gene sequence identified a germline frameshift mutation (c.107del) leading to a nonsense mutation near the N-terminus of the protein, confirming a clinical diagnosis of Peutz-Jeghers syndrome. Extensive RB1 gene analysis failed to detect germline mutations or deletions, and immunohistochemical analysis of her ocular tumors demonstrated nuclear staining of immunoreactive pRB. This result suggests that the RB1 gene is intact. We estimate the chance of trilateral retinoblastoma and PJS occurring in the same individual at approximately 1 in 134 billion live births, and we discuss the possibility that this case could be explained by a putative modifier of pRB action that is associated with the LKB1/STK11 pathway.

Four cases of autosomal dominant hypocalcaemia with hypercalciuria including two with novel mutations in the calcium-sensing receptor gene.

We present four cases with clinical and biochemical hypocalcaemia and evidence supportive of hypoparathyroidism. One case had been previously ascribed a diagnosis of idiopathic hypoparathyroidism. Following the detection of relative hypercalciuria, all cases were found to have autosomal dominant hypocalcaemia with hypercalciuria and mutations of the calcium-sensing receptor gene, of which two were novel. Increased awareness of this condition and access to genotyping enables prompt accurate diagnosis and cascade screening of first-degree relatives.

Spectrum of MECP2 mutations in New Zealand Rett syndrome patients.

BACKGROUND: Classical Rett syndrome is a severe neurodevelopmental X-linked dominant disorder affecting 1/15,000 girls worldwide. MECP2 has been identified as the predominant gene associated with Rett syndrome. Approximately 65-85% of patients with classical Rett syndrome have identifiable MECP2 mutations. In comparison, up to 57% of patients with atypical Rett have mutations in the MECP2 gene. OBJECTIVES: To investigate the spectrum and frequency of MECP2 mutations in New Zealand Rett syndrome patients and evaluate whether available clinical criteria were sufficient to direct molecular testing for Rett syndrome. PATIENTS: and Methods MECP2 coding regions were analysed by direct automated DNA sequencing and multiplex ligation dependent probe assay (MLPA) in samples from 74 patients referred for investigation of possible Rett syndrome. Necessary clinical criteria were examined in detail in 18 patients, with 7/18 having identifiable MECP2 mutations. RESULTS: Fifteen patients (20%) carried MECP2 mutations, four of which were novel (one insertion mutation, one complex rearrangement and two deletions). Eleven previously described disease-causing sequence changes and several known polymorphisms were also detected. Ninety per cent of the observed point mutations were cytosine to thymidine (C to T) transitions at a CpG dinucleotide. Only three patients with MECP2 mutations displayed all major clinical criteria associated with Rett syndrome, four were atypical cases. Of the patients not having an identified MECP2 mutation, 8 out of 11 had clinical criteria consistent with variant Rett syndrome and one of these had a balanced translocation involving chromosomes 2p25 and 6p11-12. CONCLUSIONS: This is the first genetic study of Rett syndrome in New Zealand patients describing the MECP2 mutational spectrum. The relatively low observed frequency of MECP2 mutations reflects a wide spectrum of mental disability disorders. In some cases there were insufficient clinical criteria to justify referral for Rett gene testing.