Partial deletion 5p and partial duplication 5q due to paternal pericentric inversion

Dismorfología, Citogenética y Clínica: Resultados de estudios sobre los datos del ECEMCDuring the meiotic process, most of the structural balanced chromosome alterations will affect either the specific chromosome pairing, or the chromosome and cromatides segregation, due to the number and type of chiasmata of the chromosomes implicated in those balanced rearrangements. Thus, the major clinical significance for normal carriers is the risk of transmition to their offspring unbalanced derivative. Here we present a malformed newborn infant with an abnormal chromosome 5 consisting in a partial deletion 5p and a partial duplication 5q. This abnormal chromosome 5 was a recombinant chromosome derived from a large paternal pericentric inversion. The cytogenetic study of the family showed that there were some other members who were carriers of the same balanced inversion. The clinical features of this patient are a mixture of some anomalies clearly related to the 5p deletion or "Cri-du-Chat" syndrome, like the crying and facial appearance, together with other that are describe on patients with 5q duplication, like the cardiac malformation. Nevertheless, he also shows some congenital defects as preauricular tags and anal atresia that, as for as we know, have not been previously described in patients with a similar chromosomal alteration. A literature review was performed of the genes localize at the chromosome regions involve in the inversion, in an effort to establish a relation with the patient phenotype.N

Beckwith–Wiedemann syndrome and uniparental disomy 11p: fine mapping of the recombination breakpoints and evaluation of several techniques

Beckwith–Wiedemann syndrome (BWS) is a phenotypically and genotypically heterogeneous overgrowth syndrome characterized by somatic overgrowth, macroglossia and abdominal wall defects. Other usual findings are hemihyperplasia, embryonal tumours, adrenocortical cytomegaly, ear anomalies, visceromegaly, renal abnormalities, neonatal hypoglycaemia, cleft palate, polydactyly and a positive family history. BWS is a complex, multigenic disorder associated, in up to 90% of patients, with alteration in the expression or function of one or more genes in the 11p15.5 imprinted gene cluster. There are several molecular anomalies associated with BWS and the large proportion of cases, about 85%, is sporadic and karyotypically normal. One of the major categories of BWS molecular alteration (10–20% of cases) is represented by mosaic paternal uniparental disomy (pUPD), namely patients with two paternally derived copies of chromosome 11p15 and no maternal contribution for that. In these patients, in addition to the effects of IGF2 overexpression, a decreased level of the maternally expressed gene CDKN1C may contribute to the BWS phenotype. In this paper, we reviewed a series of nine patients with BWS because of pUPD using several methods with the aim to evaluate the percentage of mosaicism, the methylation status at both loci, the extension of the pUPD at the short arm and the breakpoints of recombination. Fine mapping of mitotic recombination breakpoints by single-nucleotide polymorphism-array in individuals with UPD and fine estimation of epigenetic defects will provide a basis for understanding the aetiology of BWS, allowing more accurate prognostic predictions and facilitating management and surveillance of individuals with this disorder