[Aquagenic palmar keratoderma in a patient heterozygous for the mutation c.3197G>C in the CFTR gene]. / Kératodermie aquagénique palmaire chez une patiente hétérozygote pour la mutation c.3197G>C du gène CFTR.

BACKGROUND: Aquagenic palmar keratoderma is an entity recently described in the literature by English and McCollough in 1996. It is a rare condition affecting young women and is of unknown incidence. It causes a wrinkled and oedematous appearance in the skin of the hands that may be seen a few minutes after immersion in water. This condition may be associated with a heterozygous mutation in CFTR, the gene involved in cystic fibrosis. We report the first case of aquagenic keratoderma associated with a new mutation in the CFTR gene. PATIENTS AND METHODS: An 18-year-old patient with no particular history was referred for a painful rash on both palms occurring whenever she showered, and which had been ongoing for several months. The clinical examination was normal except for an appearance of moderate palmar hyperhidrosis. Following a test in which both hands were immersed in cold water for 5minutes, the patient presented itching, burning and pain localized to the hands. The palms were wrinkled and oedematous with white, translucent and confluent papules. A clinical diagnosis of aquagenic palmar keratoderma was made. Since this condition may be associated with mutations in the CFTR gene, a genetic study was performed for this patient and revealed the presence of a new mutation in the CFTR gene for cystic fibrosis in the heterozygous state inherited from her mother: c.3197G>C or p.Arg1066.Pro and a heterozygous polypyrimidic 5T variant inherited from her father. DISCUSSION: We report a new case of aquagenic palmar keratoderma in a patient heterozygous for a new mutation of the gene involved in cystic fibrosis. Several studies have shown association of aquagenic keratoderma with the CFTR gene for heterozygotes (carriers without cystic fibrosis), for patients with cystic fibrosis and for a patient presenting CFTRopathy with pancreatic insufficiency.

Meiotic segregation analysis in spermatozoa of pericentric inversion carriers using fluorescence in-situ hybridization.

BACKGROUND: Pericentric inversions are structural chromosomal abnormalities resulting from two breaks, one on either side of the centromere, within the same chromosome, followed by 180 degrees rotation and reunion of the inverted segment. They can perturb spermatogenesis and lead to the production of unbalanced gametes through the formation of an inversion loop. METHODS: We report here the analysis of the meiotic segregation in spermatozoa from six pericentric inversion carriers by multicolour fluorescence in-situ hybridization (FISH) and review the literature. RESULTS: The frequencies of the non-recombinant products (inversion or normal chromosomes) were 80% for the inv(20), 91.41% for the inv(12), 99.43% for the inv(2), 68.12% for the inv(1), 97% for the inv(8)(p12q21) and 60.94% for the inv(8)(p12q24.1). The meiotic segregation of 20 pericentric inversions (including ours) is now available. The frequency of unbalanced spermatozoa varies from 0 to 37.85%. The probability of a crossover within the inverted segment is affected by the chromosome and region involved, the length of the inverted segment and the location of the breakpoints. CONCLUSIONS: No recombinant chromosomes were produced when the inverted segment involved <30% of the chromosome length (independent of the size of the inverted segment). Between 30 and 50%, few recombinant chromosomes were produced, inducing a slightly increased risk of aneusomy of recombination in the offspring. The risk of aneusomy became very important when the inverted segment was >50% of the chromosome length. Studies on spermatozoa from inversion carriers help in the comprehension of the mechanisms of meiotic segregation. They should be integrated in the genetic exploration of the infertile men to give them a personalized risk assessment of unbalanced spermatozoa.

Meiotic segregation in spermatozoa of a 45,XY,-14,der(18)t(14;18)(q11;p11.3) translocation carrier: a case report.

A 35-year-old male was found to have a 45,XY,-14,der(18)t(14;18)(q11;p11.3) karyotype during the investigations for a couple with infertility for 8 years. Two sperm samples were obtained and analysed in triple fluorescence in situ hybridization (FISH) with the D18Z1 and LSI IGH/BCL2 probes. The frequency of gametes exhibiting a normal or balanced chromosomal equipment was 87.26 and 90.97% in samples 1 and 2, respectively. No statistically significant difference was found between the results of meiotic segregation of both samples. These proportions are close to those observed among Robertsonian translocation carriers. They can probably be explained by the formation of trivalent in cis configuration during meiosis I between the derivative chromosome and the normal chromosomes 14 and 18, as in Robertsonian translocation carriers. These results suggest that the configuration adopted at pachytene strongly determines the segregation mode that will be preferentially followed during anaphase I.

PMX2B, a new candidate gene for Hirschsprung's disease.

Hirschsprung's (HSCR) disease is a congenital intestinal malformation of the enteric nervous system. It is a multigenic malformation and until now, eight genes have been involved in the etiology of this disease: genes encoding proteins of the RET signaling pathway (RET, GDNF and NTN), genes participating in the endothelin (EDN) type B receptor pathway (EDNRB, EDN3 and ECE-1), the SOX10 gene and the SIP1 gene that is mutated in syndromic forms of HSCR. Mutations of these genes are found in not more than 50-60% of affected individuals. Here, we report on the results of a molecular cytogenetic study performed in a girl who presented with a syndromic short segment HSCR associated with a de novo t(4;8)(p13;p22) translocation. A comparative genomic hybridization (CGH) study found a 4p12p13 deletion. A molecular characterization of this rearrangement showed that the 4p13 deletion was 5 Mb in length and included the paired mesoderm homeobox gene (PMX2B) (MIM 603851), a gene expressed in the human embryonic gut and essential for the development of autonomic neural crest derivatives. The present observation suggests that PMX2B haploinsuffciency might predispose to HSCR.