A FURTHER PATIENT OF PURE 15q DELETION: CLINICAL AND MOLECULAR CYTOGENETIC FINDINGS

A deletion of the distal long arm of chromosome 15 is generally reported with the formation of ring chromosome 15, whereas an isolated 15q deletion is rarely described. Here we report an 11 year-old girl, from non-consanguineous parents, who was referred to the Pediatric Genetics Department with growth retardation and multiple congenital abnormalities. In her medical history, she had a cleft palate, hip dislocation and crossed renal ectopia. Dysmorphological evaluation revealed a triangular face, low-set ears, fissured cleft tongue, micrognathia, proximally placed hypoplastic thumbs, genu valgus, 2-3 toe skin syndactyly, clinodactyly and nail hypoplasia. Speech problems were also noticed. The karyotype was normal. Subtelomeric fluorescent in-situ hybridisation (FISH) analysis showed a de novo terminal deletion about 755 kb. Furthermore, the breakpoint was located within the CHSY1 gene that is responsible for Temtamy preaxial brachydactyly syndrome which shares clinical features with 15qter deletion syndrome. To the best of our knowledge, this deletion is the smallest among reported patients. It is considered that the patient presented here significant contribution to phenotype-genotype correlation in 15q deletion patients.

Interchromosomal effect in sperm of males with translocations: report of 6 cases and review of the literature

Somatic chromosomal abnormalities are frequently found in infertile men, particularly in those with low sperm count and/or seeking intracytoplasmic sperm injection. These abnormalities mostly consist of numerical sex chromosome abnormalities and translocations (Robertsonian or reciprocal). In this study, we searched for the occurrence of non-disjunction of chromosomes not involved in translocations during meiosis, phenomenon called interchromosomal effect (ICE) and first described by Lejeune (1965). Ejaculate samples of two patients carrying a Robertsonian translocation and four a reciprocal translocation patients and four controls (men with a 46,XY karyotype and normal sperm parameters) were studied in dual FISH 7-9, dual FISH 13-21 and triple FISH X-Y-18. A statistically significant increase of disomy X, Y and XY (P = 0.009, P = 0.004, P < 0.001) was found in the Robertsonian der(13;14)(q10;q10) carrier but not in the der(14;21)(q10;q10) carrier compared with controls. Among reciprocal translocation carriers, a significant increase of disomy 21 (P = 0.033) was observed in a sole patient with a t(9;22)(q21;q11.2). The increase of meiotic non-disjunction for chromosome 21 and sex chromosomes is a recurrent event found in other studies. According to our results and published data, the ICE on some specific chromosomes is likely in men carrier of a translocation, although it cannot be excluded that the aneuploidy is related to the oligoasthenoteratozoospermia usually present in these men. Moreover, this phenomenon showed interindividual variations which cannot be predicted. The risk of aneuploidy in sperm of males used for ICSI need to be evaluated. It could be superadded to that of meiotic segregation of the translocation to give a more precise and personalized risk assessment of aneuploidy in the offspring of those men.

Disease knowledge in a high-risk population for cystic fibrosis

Cystic fibrosis (CF) has high incidence (1/936 live births) and carrier rate (1/15 inhabitants) in Saguenay-Lac-Saint-Jean (SLSJ). One objective of a major enquiry among several subsets of individuals from this high-risk population for CF was to evaluate the knowledge of the disease and its genetic transmission. The overall score of correct answers pertaining to the clinical signs of CF among medical doctors (general practitioners and specialists) was 42.2 and 65.6%, respectively; it was 84.2% for questions regarding the genetic transmission of CF. The knowledge of the clinical signs was reasonable among CF patients and their parents (about 65% of correct answers), but it was much higher for the genetics (over 88% among parents). Aunts and uncles of CF children were poorly informed of the clinical signs (33.9% of correct answers) but well informed of the genetic transmission (73.8%). Specific subsets of the SLSJ population showed important gaps in the knowledge of the clinical signs of CF but, overall, they were well informed of its genetic transmission.