Welcome to the office of Dr. H. Avon Doll, Dr. Hari K. Kolli, Dr. Kaushal P. Patel and Dr. Sayeed Khalillullah. Our practice specializes in Nephrology - diseases of the kidneys and related disorders including hypertension. Meet Our Providers. Our Office. We welcome our patients at our office located at 2617 Mitcham Drive, Suite 102..