Genetic Disorders

Chromosome testing has moved from routine karyotype to targeted fluorescent in situ hybridization (FISH) to microarray analysis that examines every chromosome region for altered dosage. The principles of chromosomal, Mendelian, and mitochondrial inheritance are reviewed along with those of genomic imprinting, triplet repeat expansion, and anticipation. Clinical characteristics of chromosomal and Mendelian syndromes, sequences, and associations are presented, and key disorders described in each category as highlighted in General Pediatrics Content Outline ( www.abp.org/content/general-pediatrics-content-outline ). Outlined here for each sample disorder is its prevalence, mode of inheritance, diagnostic tests, major abnormalities, minor anomalies where appropriate, and key health supervision and preventive management guidelines. References for specific and general access to genetic and dysmorphology disorders are provided, including M numbers that can be used to search for more information on Mendelian and selected chromosome disorders at www.omim.org . See the table at the end of the chapter (see Table 4.9)