Prevalence of DFNB1 mutations in Argentinean children with non-syndromic deafness. Report of a novel mutation in GJB2.

Objective: Mutations in DFNB1 locus, containing GJB2 (connexin 26) and GJB6 (connexin 30) genes, are the most common cause of autosomal recessive non-syndromic hearing loss. More than 100 mutations in GJB2 have been reported worldwide. Two deletions in GJB6, del(GJB6-D13S1830) and del(GJB6-D13S1854), have been found to be frequent in the Spanish population.

Carrier frequency of the 35delG and A1555G deafness mutations in the Argentinean population. Impact on the newborn hearing screening.

Objective: Hearing loss is a complex multifactorial disorder caused by genetic and environmental factors. The 35delG mutation in the GJB2 gene is the most prevalent mutation in Caucasian patients with genetic sensorineural deafness. The A1555G mutation in the mitochondrial 12S rRNA is the main genetic alteration associated with aminoglycoside-induced deafness.

High specificity of head circumference to recognize N540K mutation in hypochondroplasia.

Hypochondroplasia (HCH) is a skeletal dysplasia characterized by short stature with disproportionately short arms and legs. Anthopometrics and skeletal features are very similar to achondroplasia but milder. Seventy per cent of affected individuals are heterozygous for a mutation of the FGFR3 gene.

ATR-16 due to a de novo complex rearrangement of chromosome 16.

We describe a child with ATR-16 [alpha-thalassemia (thal)/mental retardation], who was referred for genetic evaluation because of minor anomalies and developmental delay. Cytogenetic analysis demonstrated a de novo complex rearrangement of chromosome 16. Fluorescence in situ hybridization (FISH) analysis, using chromosome 16 subtelomeric probes, showed that this patient had a deletion of the distal short arm of chromosome 16 that contains the alpha-globin genes and a duplication of 16q.

Partial distal 5p trisomy resulting from paternal translocation (5;15)(p15.1;p13) in a boy with no mental retardation.

We report a boy with partial distal 5p15.1-->pter trisomy and normal development. We compared the clinical findings in our patient with those previously reported of the same 5p duplicated region.

Oral-facial-digital syndrome gabrielli type: second report.

We describe a second sporadic case, a girl, with the features of Oral-Facial-Digital, type Gabrielli. We comment on several aspects of this condition and confirm this entity as a unique syndrome, different from the other OFDS. To date, the diagnosis is based only on clinical and radiographic findings.

Trisomy 3 in two paediatric post-transplant lymphomas.

Few cytogenetic data are available concerning the chromosomal constitution of post-transplant lymphomas. We report two paediatric cases of trisomy 3, as a primary anomaly, in post-transplant lymphoproliferative disease (PTLD) associated with B immunophenotype. Using cytogenetic analysis and fluorescence in situ hybridization on chromosome preparations, we found trisomy 3 in both patients and an extra X chromosome in one.