Fanconi-Bickel syndrome as an example of marked allelic heterogeneity

Table 1 Chromosomal mapping of some inherited forms of proximal renal tubular acidosis[49,69,70]

Inherited Fanconi syndromes	Gene	Mapping
Fanconi-Bickel syndrome	SLC2A2	Chromosome 3q26.1-26.3
Autosomal recessive	SLC4A4	Chromosome 4q21
Dent´s syndrome	CLCN5	Chromosome Xp11.22
Cystinosis	SLC3A1, SLC7A9	Chromosome 2p21, Chromosome 19p13.1
Tyrosinemia type 1	FAH	Chromosome 15q23-q25
Galactosemia	GALT	Chromosome 9p13
Wilson´s disease	ATP7B	Chromosome 13q14.3-q21.1

Table 2 Allelic variants of SLC2A2 gene; first allele causes non-IDDM and the other 14 variants cause fanconi-Bickel syndrome; in addition to the newly diagnosed Egyptian variants[33]

No.	Phenotype	Mutation	dbSNP
1	Non-IDDM	SLC2A2, VAL197ILE (22, 53, 56)	[rs121909741]
2	FBS	SLC2A2, 1-BP DEL-(21, 50)
3	FBS	SLC2A2, ARG365TER (21, 22)	[rs121909742]
4	FBS	SLC2A2, ARG301TER (21, 22)	[rs121909743]
5	FBS	SLC2A2, PRO417LEU (62)	[rs121909744]
6	FBS	SLC2A2, TRP420TER (66)	[rs121909745]
7	FBS	SLC2A2, 1-BP DEL, 1363G (22)
8	FBS	SLC2A2, 1405C-T (22)
9	FBS	SLC2A2, 1-BP INS, 793C (22)
10	FBS	SLC2A2, 1264G-A (22)
11	FBS	SLC2A2, 469C-T (22)
12	FBS	SLC2A2, VAL423GLU (20)	[rs28928874]
13	FBS	SLC2A2, IVS2, A-G, -2-(20)
14	FBS	SLC2A2, GLN287TER (20)	[rs121909746]
15	FBS	SLC2A2, LEU389PRO (20)	[rs121909747]

FBS: Fanconi-Bickel syndrome.