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Intestinal Neuronal Dysplasia (IND) is a congenital disorder characterized by intestinal motility defects associated with hyperplasia of enteric ganglia. A phenotype resembling human IND has been observed in mice knocked-out for a member of the Hox11 homeobox gene family, Hox11l1, suggesting that the human homologue of this gene could be responsible for congenital disorders of intestinal innervation. However, previous mutation analysis of the coding sequence of the HOX11L1 gene in patients affected with IND detected neither mutations nor other nucleotide variants. In the present work, a detailed study of the non coding promoter region of this gene was undertaken in patients affected with IND, with Hirschsprung associated IND and with neurogenic chronic intestinal pseudo-obstruction. No alterations potentially impairing expression of HOX11L1, such as nucleotide variants, small deletions or cytogenetic alterations, could be identified thus further excluding the direct involvement of this gene in the pathogenesis of human intestinal motility disorders.

Charcot-Marie-Tooth type 4B (CMT4B) is caused by mutations in the myotubularin-related 2 gene, MTMR2, on chromosome 11q22. To date, six loss of function mutations and one missense mutation have been demonstrated in CMT4B patients. It remains to be determined how dysfunction of a ubiquitously expressed phosphatase causes a demyelinating neuropathy. An animal model for CMT4B would provide insights into the pathogenesis of this disorder. We have therefore characterized the mouse homologue of MTMR2 by reconstructing the full-length Mtmr2 cDNA as well as the genomic structure. The 1932 nucleotide open reading frame corresponds to 15 coding exons, spanning a genomic region of approximately 55 kilobases, on mouse chromosome 9 as demonstrated by fluorescence in situ hybridization analysis. A comparison between the mouse and human genes revealed a similar genomic structure, except for the number of alternatively spliced exons in the 5'-untranslated region, two in mouse and three in man. In situ hybridization analysis of mouse embryos showed that Mtmr2 was ubiquitously expressed during organogenesis at E9.5, with some areas of enriched expression. At E14.5, Mtmr2 mRNA was more abundant in the peripheral nervous system, including in dorsal root ganglia and spinal roots.

X-linked lymphoproliferative disease (XLP) is an inherited immunodeficiency characterised by selective susceptibility to Epstein-Barr virus and frequent association with malignant lymphomas chiefly located in the ileocecal region, liver, kidney and CNS. Taking advantage of a large bacterial clone contig, we obtained a genomic sequence of 197620 bp encompassing a deletion (XLP-D) of 116 kb in an XLP family, whose breakpoints were identified. The study of potential exons from this region in 40 unrelated XLP patients did not reveal any mutation. To define the critical region for XLP and investigate the role of the XLP-D deletion, detailed haplotypes in a region of approximately 20 cM were reconstructed in a total of 87 individuals from 7 families with recurrence of XLP. Two recombination events in a North American family and a new microdeletion (XLP-G) in an Italian family indicate that the XLP gene maps in the interval between DXS1001 and DXS8057, approximately 800 kb centromeric to the previously reported familial microdeletion XLP-D.

In this report, we describe a male infant with a 45,X karyotype; the entire short arm and the centromere of the Y chromosome were translocated onto the short arm of chromosome 18, resulting in an unbalanced dicentric chromosome. Breakpoints were identified by in situ fluorescence hybridization (FISH) on the proximal Yq11 and 18p11.2. Both Y and 18 centromeric alphoid sequences were identified on the derived 18 chromosome. Clinical features were compatible with 18p- syndrome and no Turner stigmata were present in our propositus. Short stature was likely to be related to the deletion of 18p and/or Yq, where a gene involved in stature determination has been located proximal to a gene involved in spermatogenesis (AZF).