Comprehensive genetic analysis of 182 unrelated families with congenital adrenal hyperplasia due to 21-hydroxylase deficiency.

BACKGROUND: Genetic analysis is commonly performed in patients with congenital adrenal hyperplasia (CAH) due to 21-hydroxylase deficiency. STUDY OBJECTIVE: The objective of the study was to describe comprehensive CYP21A2 mutation analysis in a large cohort of CAH patients. METHODS: Targeted CYP21A2 mutation analysis was performed in 213 patients and 232 parents from 182 unrelated families. Complete exons of CYP21A2 were sequenced in patients in whom positive mutations were not identified by targeted mutation analysis. Copy number variation and deletions were determined using Southern blot analysis and PCR methods. Genotype was correlated with phenotype. RESULTS: In our heterogeneous U.S. cohort, targeted CYP21A2 mutation analysis did not identify mutations on one allele in 19 probands (10.4%). Sequencing identified six novel mutations (p.Gln262fs, IVS8+1G>A, IVS9-1G>A, p.R408H, p.Gly424fs, p.R426P) and nine previously reported rare mutations. The majority of patients (79%) were compound heterozygotes and 69% of nonclassic (NC) patients were compound heterozygous for a classic and a NC mutation. Duplicated CYP21A2 haplotypes, de novo mutations and uniparental disomy were present in 2.7% of probands and 1.9 and 0.9% of patients from informative families, respectively. Genotype accurately predicted phenotype in 90.5, 85.1, and 97.8% of patients with salt-wasting, simple virilizing, and NC mutations, respectively. CONCLUSIONS: Extensive genetic analysis beyond targeted CYP21A2 mutational detection is often required to accurately determine genotype in patients with CAH due to the high frequency of complex genetic variation.

The novel human SHOX allelic variant database.

Short stature due to SHOX deficiency represents the most commonly known form of growth failure, with a frequency greater than 1:1,000 in the Caucasian population. As many different mutations can cause SHOX haploinsufficiency, a comprehensive collection of gene variants represents an essential tool to distinguish between functional variants and polymorphisms. We have created a novel and widely extended SHOX database using the "LOVD in a box-solution." This database contains not only a larger amount of mutation data (140 novel mutations were added), but also reports on phenotypic consequences, mode of inheritance, and ethnic origin, as well as on functional consequences of mutations investigated. In addition, the database now includes non-disease-related polymorphisms to enable researchers to evaluate their diagnostic findings. The database (Available at: http://hyg-serv-01.hyg.uni-heidelberg.de/lovd/index.php?select_db=SHOX; Last accessed: 12 April 2007) contains all presently known 199 intragenic mutations (SNPs as well as small deletions and insertions), 126 of which are unique. The remote user is able to search the data and to submit new mutations into the database. Furthermore, it includes general information about the SHOX gene via links to other resources such as MIM, GDB, HGMD, and HAPMAP, as well as websites of Short Stature Associations.

Comprehensive scanning of the ATM gene with DOVAM-S.

Mutation detection at the ATM locus has been difficult because of the large size of the gene (66 exons), the fact that mutations are located throughout the entire gene with no hotspots, and the difficulty of distinguishing mutations from polymorphisms. In this study, the entire coding region (exons 4-65) was scanned, as well as the adjacent intronic regions, using DOVAM-S (Detection Of Virtually All Mutations-SSCP), a robotically-enhanced, multiplexed scanning method that is a highly sensitive modification of SSCP. Forty-three unrelated patients and four obligate carriers were studied. Of the 90 expected mutant alleles, 71 were identified (79%). The mutations included 17 nonsense (24%), 20 frameshift (28%), 20 splice (28%), 10 missense (14%), one in-frame deletion (1%), and three that alter the initiation codon (4%). Among the ataxia-telangiectasia patients, two potentially causative mutations were identified in 30 individuals: 22 had two truncating mutations, four had one truncating and one missense mutation, three had two missense mutations, and one had a truncating mutation and an in-frame deletion of three amino acids. For seven A-T patients and all four obligate carriers, only one truncating mutation was detected. Six of the 43 A-T patients had no detected mutations (14%). Twelve novel mutations and six novel polymorphisms were detected. The results of this complete scan of the ATM coding region showed that 86% of causative ATM mutations were truncating and 14% were missense. DOVAM-S is a rapid, efficient method of performing A-T diagnosis and carrier testing on a clinical time scale.