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Bilateral multicystic dysplastic kidney
A rare lethal form of multicystic dysplastic kidney (MCDK), a congenital anomaly of the kidney and urinary tract (CAKUT), in which both kidneys are large, distended by non-communicating multiple cysts and non-functional.
ORPHA:97364Classification level: Subtype of disorder
- Bilateral MCDK
- Bilateral multicystic renal dysplasia
- Prevalence: Unknown
- Inheritance: -
- Age of onset: Antenatal, Neonatal
- ICD-10: Q61.4
- OMIM: -
- UMLS: C1567427 C1840451
- MeSH: C537373 D021782
- GARD: 9517
- MedDRA: -
The prevalence and incidence of bilateral MCDK are unknown.
Bilateral MCDK may be suspected antenatally at routine ultrasound scans, with the majority detected around the 20th week of gestation. It is considered a lethal entity, and most pregnancies are terminated. When born, such infants present with features of the Potter sequence (constellation of signs resulting from prolonged in utero oligohydramnios) including severe pulmonary hypoplasia and severe renal failure, limb anomalies and facial dysmorphic features, and generally die shortly after birth.
MCDK results from disrupted nephrogenesis but the exact pathogenic mechanism is still unknown. Disturbed formation of nephrons could result from impaired fetal urine flow early in development. Mutations in the HNF1B gene (17q12), coding for hepatocyte nuclear transcription factor 1beta, are known to cause unilateral MCDK and have only rarely been reported for bilateral cases. MCDK is also linked to gestational diabetes and to the use of some medications during pregnancy, such as anti-epileptic drugs.
Diagnosis is mainly based on prenatal ultrasound showing large hypoechogenic, non-communicating cysts within an irregularly outlined kidney with no visible renal pelvis. A tiny remnant kidney can be observed if the cysts have involuted. In addition, oligo/anhydramnios is present as a sign of poor functional renal development.
Differential diagnoses include bilateral pelviureteric junction obstruction, in which the largely dilated calices may appear to be cysts. Posterior urethral valves may result in oligo/anhydramnios, and the megaureter may be mistaken for renal cysts.
Ultrasonographic screening can detect MCDKs from midway through gestation.
Both sporadic and familial cases have been observed. In familial cases, transmission is autosomal dominant with a recurrence risk of 50%.
Management and treatment
As the absence of functional renal tissue results in anhydramnios with pulmonary hypoplasia (Potter sequence), which is generally lethal shortly after birth, most pregnancies with bilateral MCDK will be terminated. When children with bilateral MCDK survive the early postnatal period, renal replacement therapy will be needed.
Bilateral MCDK is considered a lethal entity.