Arising from: Kerecuk L et al. (2008) Renal tract malformations: perspectives for nephrologists. Nat Clin Pract Nephrol 4: 312–325 [doi:10.1038/ncpneph0807]

I read with interest the comprehensive article by Kerecuk et al. in the June issue of Nature Clinical Practice Nephrology.1 I was surprised by the absence of mention of the 22q11.2 microdeletion syndrome as a cause of renal tract malformations. The 22q11.2 microdeletion syndrome (OMIM #188400), also known as DiGeorge syndrome, is the most frequent deletion syndrome in humans (incidence of 1 in 4,0002), and can involve the genitourinary tract. In total, 36% of affected patients have abnormal kidneys,2 so 22q11.2 microdeletion syndrome is responsible for renal malformation in 1 in 12,000 births. In pediatric series,2,3,4 hypoplasia or agenesis of the kidney is the most common feature (17%), multicystic dysplasia can be found, obstruction is frequent (10%), and vesicoureteral reflux (4%) can be also present. In an adult cohort,5 the frequency of renal failure was 10%. The frequency of end-stage renal disease is unknown. In this adult series, the most common abnormalities were hydronephrosis (7.7%) and kidney agenesis (6%); no cystic kidney disease was described.5

Diagnosis of 22q11.2 microdeletion syndrome should be considered in patients with malformation of the kidney. Dysmorphia, abnormal voice, cardiac malformations or hypoparathyroidism are clues to the diagnosis. The molecular basis of the renal malformation is unknown; deletion of one or more genes could be responsible. The 22q11.2 microdeletion syndrome is a frequent cause of kidney malformation and should be recognized as such.