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Estimation of the Carrier Frequency and Incidence of Smith-Lemli-Opitz Syndrome in African Americans

2014-08-27 03:56:50 | BioPortfolio

Summary

RSH/Smith-Lemli-Opitz syndrome (SLOS) is one that causes mental retardation. It is common in the Caucasian population but rare in African American and African black populations. It has been shown that SLOS is caused by a specific defect in DHCR7, an enzyme used in cholesterol metabolism. Studies have already been done to determine the frequency of the SLOS-causing mutations in various geographic Caucasian populations. This study will investigate the frequency of the DHCR7 mutations in the African American population. If the frequency observed suggests that SLOS cases are not being identified in this ethnic group, the study will provide the rationale for future studies to identify these patients.

The sample size will be 1,600. The study population will consist of archived biological specimens in the form of newborn screening blood spots from two newborn screening centers, one in Maryland and one in Pennsylvania. Subjects will be of African American ethnicity, including blacks of African, Caribbean, and Central American descent.

Genomic DNA will be extracted from blood spots and screened for the six common SLOS mutations. If SLOS syndrome is found, followup will be attempted for the Maryland samples (the Pennsylvania samples will be totally anonymous).

Description

RSH/Smith-Lemli-Opitz syndrome (SLOS) is a multiple congenital anomaly/mental retardation syndrome caused by inborn error of cholesterol metabolism (Tint et al. 1994; Opitz 1999; Kelley 2000). Recent studies have shown SLOS to be one of the most common inherited metabolic defects in the Caucasian population. SLOS is believed to be rare in people of Chinese, Japanese, Indian, and Korean origin as well as in the African American and African Black population (Tsukahara et al. 1998; Yu et al 2000a; Witsch-Baumgartner et al. 2000; Witsch-Baumgartner et al. 2001, Battaile et al. 2001). The frequency spectra of DHCR7 mutations have been established for American Caucasians (Yu et al. 2000b, Battaile et al. 2001), mixed American Caucasian collection of patients (Witsch-Baumgartner et al 2000), for European ethnic groups from Poland, German/Austria, Great Britain (Witsch-Baumgartner et al. 2001) and from Italy (De Brasi et al. 1999). In these Caucasian populations, the most common mutations (IVS8-1G>C, W151X, V326L, R352W, R404C and T93M) account for 60% of SLOS mutant alleles. These suggest that frequent SLOS-causing mutations have different geographic origins and histories. This project will investigate the frequency gradient of DHCR7 mutations in the African American population.

Study Design

N/A

Conditions

Smith-Lemli-Opitz Syndrome

Location

National Institute of Child Health and Human Development (NICHD)
Bethesda
Maryland
United States
20892

Status

Completed

Source

National Institutes of Health Clinical Center (CC)

Results (where available)

View Results

Links

Published on BioPortfolio: 2014-08-27T03:56:50-0400

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Medical and Biotech [MESH] Definitions

An autosomal recessive disorder of CHOLESTEROL metabolism. It is caused by a deficiency of 7-dehydrocholesterol reductase, the enzyme that converts 7-dehydrocholesterol to cholesterol, leading to an abnormally low plasma cholesterol. This syndrome is characterized by multiple CONGENITAL ABNORMALITIES, growth deficiency, and MENTAL RETARDATION.

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Condition with a variable constellation of phenotypes due to deletion polymorphisms at chromosome location 22q11. It encompasses several syndromes with overlapping abnormalities including the DIGEORGE SYNDROME, VELOCARDIOFACIAL SYNDROME, and CONOTRUNCAL AMOMALY FACE SYNDROME. In addition, variable developmental problems and schizoid features are also associated with this syndrome. (From BMC Med Genet. 2009 Feb 25;10:16) Not all deletions at 22q11 result in the 22q11deletion syndrome.

Rare congenital disorder with multiple anomalies including: characteristic dysmorphic craniofacial features, musculoskeletal abnormalities, neurocognitive delay, and high prevalence of cancer. Germline mutations in H-Ras protein can cause Costello syndrome. Costello syndrome shows early phenotypic overlap with other disorders that involve MAP KINASE SIGNALING SYSTEM (e.g., NOONAN SYNDROME and cardiofaciocutaneous syndrome).

An autosomal dominant aneurysm with multisystem abnormalities caused by increased TGF-BETA signaling due to mutations in type I or II of TGF-BETA RECEPTOR. Additional craniofacial features include CLEFT PALATE; CRANIOSYNOSTOSIS; HYPERTELORISM; or bifid uvula. Phenotypes closely resemble MARFAN SYNDROME; Marfanoid craniosynostosis syndrome (Shprintzen-Goldberg syndrome); and EHLERS-DANLOS SYNDROME.

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