| Resumo: | Chromosome 1p36 deletion syndrome (MIM #607872) was first described in 1997 by Shapira et al. This condition is compatible with a monosomy of the 1p36 band in the distal region of the short arm of chromosome 1 and is the most common terminal deletion in humans, with an estimated prevalence of approximately 1 in 5,000 live births. This constitutional deletion is associated with mental retardation, developmental delay, seizures, hypotonia and heart defects. The syndrome is also characterized by several distinct dysmorphic features, including large anterior fontanels, microcephaly, brachycephaly, deep-set eyes, flat nose and nasal bridge, and pointed chin. The 1p36 band is not very clearly visible using classical cytogenetics, and it is therefore difficult to detect these deletions in banded karyotypes. Fluorescence in situ hybridization (FISH) and multiplex ligation-dependent probe amplification (MLPA) analysis have increasingly been used, in addition to classical cytogenetic analysis, in children with mental retardation in order to identify this chromosomal abnormality. The authors present four patients between 1 month and 14 years of age with apparently normal karyotypes. Using molecular cytogenetic techniques, all cases showed a “pure” 1p36 deletion: three were detected by FISH (CEB108/T7, located at 1p36.3, Vysis) and are “de novo”; the fourth was detected by MLPA (P036 and P070, MRC Holland) analysis, and its origin is still unknown. The phenotypes of these patients are described and compared with other cases having this syndrome, described in the literature. We also emphasize the importance of good clinical characterization in order to establish the best cytogenetic strategy to assure accurate diagnosis.
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