Gene-environment interplay is a general term that covers several divergent concepts with different meanings and different implications. In this review, we evaluate research evidence on four varieties of gene-environment interplay. First, we consider epigenetic mechanisms by which environmental influences alter the effects of genes. Second, we…

Background: Speech sound disorder (SSD) is a common childhood disorder characterized by developmentally inappropriate errors in speech production that greatly reduce intelligibility. SSD has been found to be associated with later reading disability (RD), and there is also evidence for both a cognitive and etiological overlap between the two…

Leukoencephalopathy with vanishing white matter (VWM) is an autosomal recessive brain disorder, most often with a childhood onset. Magnetic resonance imaging and spectroscopy indicate that, with time, increasing amounts of cerebral white matter vanish and are replaced by fluid. Autopsy confirms white matter rarefaction and cystic degeneration. The…

Fragile X syndrome (FXS) is the most common form of heritable mental retardation, affecting (~ around) 1 in 4000 males. The syndrome arises from expansion of a trinucleotide repeat in the 5'-untranslated region of the fragile X mental retardation 1 ("FMR1") gene, leading to methylation of the promoter sequence and lack of the fragile X mental…

The neuropsychological underpinnings of Attention Deficit Hyperactivity Disorder (ADHD) and Reading Disability (RD) and their comorbidity may be studied usefully with the double dissociation design. The results of studies using the double dissociation method may be linked to the search for an endophenotype of ADHD and RD and their comorbidity.…

Autism is a heterogeneous disorder that can reveal a specific genetic disease. This paper describes several genetic diseases consistently associated with autism (fragile X, tuberous sclerosis, Angelman syndrome, duplication of 15q11-q13, Down syndrome, San Filippo syndrome, MECP2 related disorders, phenylketonuria, Smith-Magenis syndrome, 22q13…

This paper proposes a genetic development of the concept of limit of a sequence leading to a definition, through a succession of proofs rather than through a succession of sequences or a succession of epsilons. The major ideas on which it is based are historical and depend on Euclid, Archimedes, Fermat, Wallis and Newton. Proofs of equality by…

Today, societal decisions in areas of complexity are often dominated by one of three alternative ways: (a) by scientists, nowadays often in combination with commercial interest; (b) by politicians alone; and (c) by simply "laissez-faire," or "the tyranny of small steps." None of these three ways of decision making is fully…

The authors reviewed recent quantitative genetic research on learning disabilities that led to the conclusion that genetic diagnoses differ from traditional diagnoses in that the effects of relevant genes are largely general rather than specific. This research suggests that most genes associated with common learning disabilities--language…

CPEB is a sequence-specific RNA binding protein that regulates translation at synapses. In neurons of CPEB knockout mice, synaptic efficacy is reduced. Here, we have performed a battery of behavioral tests and find that relative to wild-type animals, CPEB knockout mice, although similar on many baseline behaviors, have reduced extinction of…

Immunological, endocrinological, and haematological abnormalities are relatively common in people with Down syndrome (Cuadrado & Barrena, 1996; Decoq & Vincker, 1995; Hestnes et al., 1991; Sustrova & Strbak, 1994; Nespoli, Burgio, Ugazio & Maccario, 1993; Kempski, Chessells & Reeves, 1997; Kivivuori, Rajantie, & Siimes, 1996; David et al., 1996;…

Individuals with fragile X mental retardation 1 ("FMR1") premutation (55 to 200 CGG repeats) are typically unaffected by fragile X syndrome. However, a subgroup of older males with the premutation have developed a neurological syndrome, which usually begins between 50 and 70 years and is associated with a progressive intention tremor and/or ataxia…

We report on a case of a 6-year-old female with partial trisomy 8p(21-23) associated with autism, mild dysmorphic features, and moderate learning disability. Although mental retardation is a common finding in patients with mosaic trisomy 8 or partial trisomy of various regions of chromosome 8, only two cases associated with autism have been…

Because of the daily impact of biotechnology, it is important that students have some knowledge and experience with biotechnology in order to enable them to deal with the issues that arise as a result of its implementation. The purpose of this workbook is to assist in the efforts to expose students to the concepts of biotechnology through hands-on…

Expanded newborn screening programs and subsequent detection of rare genetic disorders challenge parents and their medical providers to learn about the treatment and management of these disorders. Many people seek medical information on the Internet but may encounter requests for registration or fees, or find that resources are out of date,…