CMA analysis identifies homozygous deletion of in 2 brothers with primary Microcephaly-1.

Background: Homozygous mutations and deletions of the microcephalin gene (; OMIM *607117) have been identified as a cause of autosomal recessive primary microcephaly and intellectual disability (MIM #251200). Previous studies in families of Asian descent suggest that the severity of the phenotype may vary based on the extent of the genomic alteration. We report chromosome microarray (CMA) findings and the first described family study of a patient with primary microcephaly in a consanguineous Hispanic family.

Regions of homozygosity identified by oligonucleotide SNP arrays: evaluating the incidence and clinical utility.

Copy neutral segments with allelic homozygosity, also known as regions of homozygosity (ROHs), are frequently identified in cases interrogated by oligonucleotide single-nucleotide polymorphism (oligo-SNP) microarrays. Presence of ROHs may be because of parental relatedness, chromosomal recombination or rearrangements and provides important clues regarding ancestral homozygosity, consanguinity or uniparental disomy. In this study of 14 574 consecutive cases, 832 (6%) were found to harbor one or more ROHs over 10 Mb, of which 651 cases (78%) had multiple ROHs, likely because of identity by descent (IBD), and 181 cases (22%) with ROHs involving a single chromosome.

Abnormalities in spontaneous abortions detected by G-banding and chromosomal microarray analysis (CMA) at a national reference laboratory.

Background: Cytogenetic evaluation of products of conception (POC) for chromosomal abnormalities is central to determining the cause of pregnancy loss. We compared the test success rates in various specimen types and the frequencies of chromosomal abnormalities detected by G-banding analysis with those found by Oligo-SNP chromosomal microarray analysis (CMA). We evaluated the benefit of CMA testing in cases of failed culture growth.

Neocentric X-chromosome in a girl with Turner-like syndrome.

Background: Neocentromeres are rare human chromosomal aberrations in which a new centromere has formed in a previously non-centromeric location. We report the finding of a structurally abnormal X chromosome with a neocentromere in a 15-year-old girl with clinical features suggestive of Turner syndrome, including short stature and primary amenorrhea.

Result: G-banded chromosome analysis revealed a mosaic female karyotype involving two abnormal cell lines.

Inherited and de novo 22q11.2 distal duplications in two patients with autistic features, speech delay and no dysmorphology.

In a screen of patients by fluorescence in-situ hybridization and array comparative genomic hybridization in the past two years (July 2007--July 2009), we identified two patients with duplications in the 22q11.22-23, occurring outside the common DiGeorge syndrome/valocardiofacial syndrome region. Fluorescent in-situ hybridization, multiplex ligation-dependent probe amplification and high density bacterial artificial chromosomes and oligo arrays were used to identify the extent of the duplications.

Spectral Karyotyping for identification of constitutional chromosomal abnormalities at a national reference laboratory.

Spectral karyotyping is a diagnostic tool that allows visualization of chromosomes in different colors using the FISH technology and a spectral imaging system. To assess the value of spectral karyotyping analysis for identifying constitutional supernumerary marker chromosomes or derivative chromosomes at a national reference laboratory, we reviewed the results of 179 consecutive clinical samples (31 prenatal and 148 postnatal) submitted for spectral karyotyping. Over 90% of the cases were requested to identify either small supernumerary marker chromosomes (sSMCs) or chromosomal exchange material detected by G-banded chromosome analysis.