What are the signs and symptoms of Pachyonychia congenita? The signs and symptoms of pachyonychia congenita (PC) vary based on the specific keratin gene involved (KRT6A, KRT6B, KRT6C, KRT16, and KRT17) and the specific gene mutation. However, the most common features of the condition include: Thickened nails Plantar hyperkeratosis (thickened skin on the soles of the feet) with underlying blisters Plantar pain Various types of cysts (i.e. steatocystoma and pilosebaceous cysts - two types of sebaceous gland cysts) Follicular hyperkeratosis (small bumps at the base of hairs) Leukokeratosis (white patches on the tongue, in the mouth, or on the inside of the cheek) Some affected people may also develop calluses on the palms of the hands (palmar hyperkeratosis), sores at the corner of the mouth; natal teeth; a hoarse cry or voice caused by white film on the larynx (voice box); and/or intense pain when beginning to eat or swallow. For more specific information on the signs and symptoms of PC, including specific features that are not associated with the condition, please visit the Pachyonychia Congenita Project's Web site. The Human Phenotype Ontology provides the following list of signs and symptoms for Pachyonychia congenita. If the information is available, the table below includes how often the symptom is seen in people with this condition. You can use the MedlinePlus Medical Dictionary to look up the definitions for these medical terms. Signs and Symptoms Approximate number of patients (when available) Abnormality of nail color 90% Abnormality of the fingernails 90% Abnormality of the toenails 90% Hyperhidrosis 90% Abnormal blistering of the skin 50% Anonychia 50% Carious teeth 50% Ichthyosis 50% Neoplasm of the skin 50% Alopecia 7.5% Cataract 7.5% Cognitive impairment 7.5% Corneal dystrophy 7.5% Hepatomegaly 7.5% Laryngomalacia 7.5% Respiratory insufficiency 7.5% Autosomal dominant inheritance - Chapped lip - Dry hair - Epidermoid cyst - Follicular hyperkeratosis - Furrowed tongue - Gingivitis - Heterogeneous - Hoarse voice - Nail dysplasia - Nail dystrophy - Natal tooth - Onychogryposis of toenails - Oral leukoplakia - Palmar hyperkeratosis - Palmoplantar hyperhidrosis - Palmoplantar hyperkeratosis - Palmoplantar keratoderma - Plantar hyperkeratosis - Sparse eyebrow - Sparse scalp hair - Steatocystoma multiplex - Subungual hyperkeratosis - Thick nail - The Human Phenotype Ontology (HPO) has collected information on how often a sign or symptom occurs in a condition. Much of this information comes from Orphanet, a European rare disease database. The frequency of a sign or symptom is usually listed as a rough estimate of the percentage of patients who have that feature. The frequency may also be listed as a fraction. The first number of the fraction is how many people had the symptom, and the second number is the total number of people who were examined in one study. For example, a frequency of 25/25 means that in a study of 25 people all patients were found to have that symptom. Because these frequencies are based on a specific study, the fractions may be different if another group of patients are examined. Sometimes, no information on frequency is available. In these cases, the sign or symptom may be rare or common.