Severe form of thyroid hormone resistance in a patient with homozygous/hemizygous mutation of T3 receptor gene

Resistance to thyroid hormone syndrome (RTH) is a rare disorder, usually inherited as an autosomal dominant trait. Patients with RTH are usually euthyroid but can occasionally present with signs and symptoms of thyrotoxicosis or rarely with hypothyroidism. Affected individuals are usually heterozygous for mutations in the thyroid hormone receptor beta gene (TR-beta). We present a patient with RTH found to be homo-/hemizygous for a mutation in the TR-beta gene. The single nucleotide substitution I280S (1123T-->G) was present either on both alleles or in a hemizygous form with complete deletion of the second allele. The I280S mutation was recently reported in a heterozygous patient. The severe phenotype with seriously impaired intellectual development, hyperkinetic behaviour, tachycardia, hearing and visual impairment is probably due to the dominant negative effect of the I280S mutant protein and the absence of any functional TR-beta.

Tapetoretinal degeneration in brothers with apparent Cohen syndrome: nosology with Mirhosseini-Holmes-Walton syndrome

We report on 2 brothers with marked eye anomalies, documented with histopathological studies, and several other findings fitting the diagnosis of both the Cohen and the Mirhosseini-Holmes-Walton syndromes. In accordance with Norio and Raitta (Norio R, Raitta C (1986): Am J Med Genet 25:397-398) we come to the conclusion that these 2 syndromes constitute one clinical but possibly heterogeneous entity.

Studies on the juxtaglomerular apparatus. IV. Freeze-fracturing of membrane surfaces

The juxtaglomerular apparatus of the rat was studied after freeze-fracturing with special respect to intercellular junctions. It was found that juxtaglomerular granulated cells of the vas afferens are interconnected by gap junctions to adjacent cells (granulated cells, possibly also smooth muscle cells). Gap junctions have also been found on the surface of lacis cells and mesangial cells. It is therefore concluded that these cells of the juxtaglomerular apparatus and the glomerulus--granulated cells (possibly also smooth muscle cells) of the vas afferens, lacis cells and mesangium cells--form a functional system reacting in a coordinated manner to physiological stimuli.