HCCS and Hearing impairment: Microphthalmia with linear skin defects syndrome (MLS), or linear skin defects with multiple congenital anomalies 1 (LSDMCA1), also features linear skin defects and hearing impairment, and is caused by pathogenic variants in the holocytochrome c-type synthase-encoding HCCS gene [175,176,177,178,179].