Renal calcification in children with renal tubular acidosis: What a paediatrician ‎should ‎know‎

Table 4 Genetic causes of different types of renal tubular acidosis

Gene involved	Inheritance	Location of gene	RTA type caused	Affected protein	Main clinical feature
SLC4A1 gene	AD	17q21-q22	Type 1 RTA	AE1	Type 1 RTA, hereditary spherocytosis
	AR
CA2 gene	AR	8q21.2	Type 1 RTA, type 3 RTA	CA II	Osteopetrosis, brain calcification, RTA
ATP6V1B1	AR	2q13	Type 1 RTA	H+-ATPase	Sensorineural deafness
ATP6V0A4		7q33-q34
SLC4A2 gene	AR	7q36.1	Type 2 RTA	AE2	PBC
SLC4A4 gene	AR	4q13.3	Type 2 RTA	(NBC)	Ocular abnormalities
SLC2A2 gene	AR	3q26.2	Type 2 RTA	GLUT2	Fanconi-Bickel syndrome, NIDDM
CLCN5 gene	X-linked recessive	Xp11.23	Type 2 RTA	H+/Cl- exchanger	Dent disease type 1, HHR
OCRL1 gene	X-linked recessive	Xq26.1.	Type 2 RTA	OCRL enzyme	Dent disease, type 2, LOCRS
NR3C2 (MR) gene	AD	4p	Type 4 RTA	MLR NRC	PHA1, hyperkalemia, salt wasting & hypotension
SCNN1A, SCNN1B, and SCNN1G genes	AR	SCNN1A (12p3). SCNN1B, & SCNN1G located in (16p12-p13)	Type 4 RTA	ENaC	Liddle syndrome, sodium loss from the kidneys and other organs, including the sweat glands, salivary glands, and colon

AD: Autosomal dominant; AE1: Anion exchanger 1 protein; AE2: Anion exchanger 2 protein; AR: Autosomal recessive; CA II: Carbonic anhydrase II; ENaC: Epithelial sodium channels located on the luminal membrane of the collecting tubule; GLUT2: Glucose transporter 2; HHR: Hereditary hypophosphatemic rickets; OCRL: Lowe oculocerebrorenal syndrome; MLR NRC: The mineralocorticoid receptor (or MR, MLR, MCR), also known as the aldosterone receptor or nuclear receptor subfamily 3, MR: Mineralocorticoid receptor, group C; NBC: Sodium bicarbonate cotransporter, which regulates bicarbonate secretion, absorption, and intracellular pH. NIDDM: Noninsulin-dependent diabetes mellitus, PBC: Primary biliary cirrhosis; PHA1: Primary pseudohypoaldosteronism type 1; RTA: Renal tubular acidosis.