Genetic linkage analysis of the murine developmental mutant velvet coat (Ve) and the distal chromosome 15 developmental genes Hox-3.1, Rar-g, Wnt-1, and Krt-2

Hoxc13 mutant mice lack external hair

Hox genes are usually expressed temporally and spatially in a colinear manner with respect to their positions in the Hox complex. Consistent with the expected pattern for a paralogous group 13 member, early embryonic Hoxc13 expression is found in the nails and tail. Hoxc13 is also expressed in vibrissae, in the filiform papillae of the tongue, and in hair follicles throughout the body; a pattern that apparently violates spatial colinearity. Mice carrying mutant alleles of Hoxc13 have been generated by gene targeting. Homozygotes have defects in every region in which gene expression is seen. The most striking defect is brittle hair resulting in alopecia (hairless mice). One explanation for this novel role is that Hoxc13 has been recruited for a function common to hair, nail, and filiform papilla development.

The role of keratin proteins and their genes in the growth, structure and properties of hair

The importance of wool in the textile industry has inspired extensive research into its structure since the 1960s. Over the past several years, however, the hair follicle has increased in significance as a system for studying developmental events and the process of terminal differentiation. The present chapter seeks to integrate the expanding literature and present a broad picture of what we know of the structure and formation of hair at the cellular and molecular level. We describe in detail the hair keratin proteins and their genes, their structure, function and regulation in the hair follicle, and also the major proteins and genes of the inner and outer root sheaths. We discuss hair follicle development with an emphasis on the factors involved and describe some hair genetic diseases and transgenic and gene knockout models because, in some cases, they stimulate natural mutations that are advancing our understanding of cellular interactions in the formation of hair.

Chromosomal locations and modes of action of genes of the retinoid (vitamin A) system support their involvement in the etiology of schizophrenia

Vitamin A (retinoid), an essential nutrient for fetal and subsequent mammalian development, is involved in gene expression, cell differentiation, proliferation, migration, and death. Retinoic acid (RA) the morphogenic derivative of vitamin A is highly teratogenic. In humans retinoid excess or deficit can result in brain anomalies and psychosis. This review discusses chromosomal loci of genes that control the retinoid cascade in relation to some candidate genes in schizophrenia. The paper relates the knowledge about the transport, delivery, and action of retinoids to what is presently known about the pathology of schizophrenia, with particular reference to the dopamine hypothesis, neurotransmitters, the glutamate hypothesis, retinitis pigmentosa, dermatologic disorders, and craniofacial anomalies.

Ataxia and a cerebellar defect in the exencephaly-prone SELH/Bc mouse stock

SELH/Bc inbred mice have an abnormal mechanism of anterior neural tube closure and 10-20% of embryos have a lethal neural tube closure defect, exencephaly. Our previous studies have focused on this multifactorial threshold trait. However, SELH mice are also characterized by another trait that also shows non-Mendelian transmission ratios, an ataxia recognized in juvenile and adult mice. Here we report our first genetic and morphological studies of the ataxia trait. Recent pedigree records for the SELH colony showed that 7% of the 467 weaned progeny from normal breeding pairs were ataxic; 17 of the 20 pairs produced ataxic progeny. This result was statistically consistent with the hypothesis that all SELH mice have the ataxic genotype, which is expressed in only 7% of them. Genetic studies of an outcross to a normal strain and the subsequent F2 and testcross of the F2 were also done. The results were consistent with a one or two gene locus cause of liability to ataxia in SELH mice. The genetic correlation between exencephaly production and ataxia production for a sample of nine F2 males was 0.35, as expected if both traits are caused by the same genes, but was not statistically significant. In another approach, we examined the morphology of brains from normal and ataxic adult SELH mice. All 20 brains from non-ataxic SELH mice were morphologically normal. In all 18 brains from ataxic SELH mice the cerebellum was abnormal, lacking the vermis, and characterized by a midline fissure. This phenotype in mice has previously been known in Mendelian mutants at the Wnt-1 locus.(ABSTRACT TRUNCATED AT 250 WORDS)