Genotype and allele frequency of a 32-base pair deletion mutation in the CCR5 gene in various ethnic groups: absence of mutation among Asians and Pacific Islanders.

BACKGROUND: A 32-base pair (bp) deletion mutation in the beta-chemokine receptor CCR5 gene has been associated with resistance against human immunodeficiency virus type 1 (HIV-1) infection and disease. Large-scale studies conducted among Caucasians indicate that individuals who are homozygous for this deletion mutation (D32/D32) are protected against HIV-1 infection despite multiple high-risk exposures, whereas CCR5/ D32 heterozygotes have a slower progression to acquired immunodeficiency syndrome (AIDS). OBJECTIVE: To determine the genotype and allele frequencies of the CCR5 gene 32-bp deletion mutation among ethnically diverse non-Caucasian populations. METHODS: DNA, extracted from blood collected between 1980 and 1997 from 1912 individuals belonging to various ethnic groups, including 363 Caucasians, 303 Puerto Rican Hispanics, 150 Africans, 606 Asians, and 490 Pacific Islanders, were analyzed for the CCR5 gene 32-bp deletion mutation by a polymerase chain reaction (PCR)-based assay, using an oligonucleotide primer pair designed to discriminate CCR5 alleles without restriction endonuclease analysis. RESULTS: The comparative frequency of CCR5/D32 heterozygosity was 61 of 363 (16. 8%) in Caucasians, 17 of 303 (5.6%) in Puerto Rican Hispanics, 9 of 490 (1.8%) in Pacific Islanders, 0 of 606 (0%) in Asians, and 0 of 150 (0%) in Africans. CONCLUSIONS: The data confirm the high frequency of CCR5/D32 heterozygosity among Caucasians. Intermediate and low-level D32 allele frequencies among Puerto Rican Hispanics and Hawaiians could be attributed to recent European Caucasian gene flow. By contrast, the inability to detect the D32 allele among Asians and other Pacific Islander groups suggests that other mechanisms are responsible for resistance to HIV-1 infection in these populations.

Goodness of fit in the home: its relationship to school behavior and achievement in children with learning disabilities.

This study examined whether a "goodness of fit" theoretical model, applied to families with and without children with learning disabilities, would be valuable in understanding the children's performance in school. A home interview was conducted with 63 families with a child with learning disabilities and 53 families with a comparable child without learning disabilities. The mothers were asked to rate how their own child fit into the family's expectations for children. It was found that, for both groups of families, children who were rated as a "poor fit" in the home demonstrated less positive behavior in the classroom and poorer achievement over the elementary school years. There was some evidence that poor fit in the home was even more negatively related to outcomes for children with learning disabilities. Discussion is centered on the importance of this theoretical model for understanding the importance of the home on successful school function.

Visual discrimination of letter-like forms and its relationship to achievement over time in children with learning disabilities.

The purpose of this study was to better understand whether visual discrimination abilities are related to reading intelligence and other achievement areas in children with learning disabilities and normally achieving children. Children with visual discrimination problems were identified using the Gibson letter-like visual discrimination task. This task was given to a large sample of children with learning disabilities as well as a sample of normally achieving children. All children were followed throughout elementary school. Results indicated that children with learning disabilities who had visual discrimination problems at 6 or 7 years of age performed more poorly in reading and general achievement over the elementary school years in comparison to the other children with learning disabilities and compared to normally achieving children. Discussion centers around the importance of this skill for reading.