16p11.2 transcription factor MAZ is a dosage-sensitive regulator of genitourinary development

Genitourinary (GU) birth defects are among the most common yet least studied congenital malformations. Congenital anomalies of the kidney and urinary tract (CAKUTs) have high morbidity and mortality rates and account for ∼30% of structural birth defects. Copy number variation (CNV) mapping revealed that 16p11.2 is a hotspot for GU development. The only gene covered collectively by all of the mapped GU-patient CNVs was MYC-associated zinc finger transcription factor (MAZ), and MAZ CNV frequency is enriched in nonsyndromic GU-abnormal patients. Knockdown of MAZ in HEK293 cells results in differential expression of several WNT morphogens required for normal GU development, including Wnt11 and Wnt4. MAZ knockdown also prevents efficient transition into S phase, affects transcription of cell-cycle regulators, and abrogates growth of human embryonic kidney cells. Murine Maz is ubiquitously expressed, and a CRISPR-Cas9 mouse model of Maz deletion results in perinatal lethality with survival rates dependent on Maz copy number. Homozygous loss of Maz results in high penetrance of CAKUTs, and Maz is haploinsufficient for normal bladder development. MAZ, once thought to be a simple housekeeping gene, encodes a dosage-sensitive transcription factor that regulates urogenital development and contributes to both nonsyndromic congenital malformations of the GU tract as well as the 16p11.2 phenotype.