The diagnostic lesion consists of irregular thinned and thickened areas of the GBM with splitting and irregular multilaminated appearance of the lamina densa, so-called basket weaving (Fig. 7.1) (2). In between these lamina, granular, mottled material is present. In children with classic Alport's, the GBM may show only thinning rather than thickening. Female carriers of the COL4A5 mutation also show only thin basement mem-
branes, as do carriers of the autosomal recessive form of Alport's. The GBM thickness normally increases with age (12-14). Normal thickness in adults in one series was 373 ± 42 nm in men versus 326 ± 45 nm in women. Glomerular basement thickness <250 nm has been used as a cutoff for diagnosis in many series. In children, the diagnosis of thin basement membranes must be made with caution, establishing normal age-matched controls within each laboratory. In our laboratory, we found a range of GBM thickness in normal children from approximately 110 nm at age 1 year to 222 ± 14 nm in 7-year-olds.
Was this article helpful?