Renal tubular acidosis (RTA) [29 genes]

Renal tubular acidosis is characterized by the presence of metabolic acidosis with normal GAP anion due to decreased renal reabsorption of bicarbonate and/or excretion of hydrogen ions. There are also presentations in which the patient’s acid-base status is normal under physiological conditions. On some occasions, it can be associated with the development of kidney stones.

Four types have been described:

• Type 1: Distal. It can present syndromically with sensorineural hearing loss.
• Type 2: Proximal. It may present with ocular anomalies or Fanconi syndrome.
• Type 3: Mixed. It can present with osteopetrosis, brain calcifications, nephrocalcinosis, facial dysmorphism, conductive hearing loss, and cognitive deficit.
• Type 4: Renal tubular acidosis with hyperkalemia.

Unknown

• Alkaline therapy
• Nephrocalcinosis and nephrolithiasis prevention
• Correction of electrolytic alterations
• Genetic counseling

Identifying genetic variants causing renal tubular acidosis allows for a precise molecular diagnosis that provides the information necessary to perform genetic counseling, direct patient management, and offers predictive value to carrier patients.

This panel is indicated when renal tubular acidosis is suspected, which may include the following clinical characteristics:

• Metabolic acidosis with normal GAP anion
• Hypokalemia (except Type 4)
• Hypercalciuria, nephrocalcinosis, nephrolithiasis (Type 1 and 3)
• Inappropriately alkaline urine (Type 1)
• Stunted growth