The majority of large deletions on the short arm of chromosome 5 are associated with CDC. 2 CDC is the most common human classical deletion syndrome with an incidence varying from 1 in 20 000 to 1 in 50 000 births. 1, 2 The high-pitched monotone cry is the most prominent clinical characteristic and is usually considered as the hallmark of CDC in newborn children. The typical features of CDC normally include a high-pitched cat-like cry, microcephaly, round face, hypertelorism, micrognathia, epicanthic folds and mental retardation. The other two genes are expressed uniformly in all tissues tested, which suggest that they are housekeeping genes.Ĭri-du-chat syndrome (CDC, OMIM 123450) first described by Lejeune in 1963 1 is a well-described partial aneusomy, resulting from deletions on the short arm of chromosome 5. These results suggest that one candidate gene, FLJ25076, encodes a ubiquitin-conjugated enzyme E2 type, which is locally expressed in thoracic and scalp tissues. Three genes, FLJ25076, a homolog to a ubiquitin-conjugating enzyme UBC-E2, FLJ20303, a nucleolar protein NOP2, which may play a role in the regulation of the cell cycle and MGC5309, a protein with similarity to Nut2, a Drosophila transcriptional coactivator, have been characterized and expression profiles determined by quantitative PCR. Genome analysis of this critical region reveals a gene-rich sequence containing five known genes, five putative genes and three spliced EST sequences, altogether 71 predicted exons. Using PCR, the critical region for the cat-like cry is mapped to a short 640 kbp region on chromosome 5p. In this study, the distal breakpoints of two interstitial deletions in two clinical distinctive CDC patients are analysed, one with and one without the cat-like cry. Using a strategy of ‘phenotype dissection’, the critical region for cat-like cry was mapped to the chromosomal segment 5p15.3–5p15.2 in previous reports. The cat-like cry is the most prominent clinical characteristic in newborn children and is usually considered as diagnostic for the CDC syndrome. The clinical features of CDC normally include high-pitched cat-like cry, mental retardation, microcephaly, hypertelorism and epicanthic folds. Cri-du-chat (CDC, OMIM 123450) is a chromosomal syndrome that results from partial deletions on the short arm of chromosome 5.
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