Abstract
The etiology of mental retardation/developmental delay (MRDD) remains a challenge to geneticists and clinicians and can be correlated to environmental and genetic factors. Chromosomal aberrations are common causes of moderate to severe mental retardation and may represent 10% of these occurrences. Here we report the case of a boy with development delay, hypoplasia of corpus callosum, microcephaly, muscular hypotonia, and facial dysmorphisms. A deletion of 7q36.1 → 36.3 and duplication of 9p22.3 → 23 was detected as a result of an unbalanced translocation of paternal origin. Breakpoint delimitation was achieved with array comparative genomic hybridization assay. Additional multiplex ligation dependent probe amplification (MLPA) analyzes confirmed one copy loss of 7q36.3 region and one copy gain of 9p24.3 region. Patient resultant phenotype is consistent with the already described findings for both 7q deletion and 9p duplication syndromes.
Highlights
Mental retardation/developmental delay (MRDD) is a relevant public health concern, since it may represent one of the major causes of child disability, with prevalence estimated in 1-3% [1]
More than 150 cases of 9p duplication are reported in literature [7] and common features include mental retardation, failure to thrive, hypotonia, microcephaly, low set malformed ears, upwardslanted eyes, small palpebral fissures, congenital heart
We present the case of a patient exhibiting deletion of 7q36.1 → 36.3 and duplication of 9p22.3 → 23 as a result of an unbalanced translocation from paternal origin
Summary
Mental retardation/developmental delay (MRDD) is a relevant public health concern, since it may represent one of the major causes of child disability, with prevalence estimated in 1-3% [1]. More than 150 cases of 9p duplication are reported in literature [7] and common features include mental retardation, failure to thrive, hypotonia, microcephaly, low set malformed ears, upwardslanted eyes, small palpebral fissures, congenital heart. At age of 3 years old and 5 months child exhibited failure to thrive (weight = 9.5 kg, p < 3; length = 86.0 cm, 9p < 5), psychomotor and language delay, severe microcephaly (OFC = 43.5 cm, p < 3) and craniofacial dysmorphisms became more evident. Constitutional Chip 4.0 (Perkin Elmer, Norwalk) was employed and was comprised of 5000 BAC clones spotted in Figure 1 Patient phenotype at 5 years-old. One copy loss of VIPR2 gene (7q36.3) and one copy gain of DMRT1 gene (9p24.3) were detected in the patient DNA analysis (Figure 3)
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