SCN9A neuropathic pain syndromes (SCN9A-NPS) comprise SCN9A erythromelalgia (EM), SCN9A paroxysmal extreme pain disorder (PEPD), and SCN9A small fiber neuropathy (SFN). SCN9A-EM is characterized by recurrent episodes of bilateral intense, burning pain, and redness, warmth, and occasionally swelling. While the feet are more commonly affected than the hands, in severely affected individuals the legs, arms, face, and/or ears may be involved. SCN9A-PEPD is characterized by neonatal or infantile onset of autonomic manifestations that can include skin flushing, harlequin (patchy or asymmetric) color change, tonic non-epileptic attacks (stiffening), and syncope with bradycardia. Later manifestations are episodes of excruciating deep burning rectal, ocular, or submandibular pain accompanied by flushing (erythematous skin changes). SCN9A-SFN is characterized by adult-onset neuropathic pain in a stocking and glove distribution, often with a burning quality; autonomic manifestations such as dry eyes, mouth, orthostatic dizziness, palpitations, bowel or bladder disturbances; and preservation of large nerve fiber functions (normal strength, tendon reflexes, and vibration sense).

In its rare complete form, 'prune belly' syndrome (PBS) comprises megacystis (massively enlarged bladder) with disorganized detrusor muscle, cryptorchidism, and thin abdominal musculature with overlying lax skin (summary by Weber et al., 2011).

Aplasia of lacrimal and salivary glands (ALSG) is a rare autosomal dominant condition characterized by irritable eyes, epiphora (constant tearing), and xerostomia (dryness of the mouth), which increases risk of dental erosion, dental caries, periodontal disease, and oral infections. ALSG has variable expressivity, and affected individuals may have aplasia or hypoplasia of the lacrimal, parotid, submandibular, and sublingual glands and absence of the lacrimal puncta. In affected individuals, the misdiagnosis is often made of the more prevalent disorder Sjogren syndrome (270150), an autoimmune condition characterized by keratoconjunctivitis sicca and xerostomia. Both sporadic and familial cases of ALSG have been described (summary by Entesarian et al., 2005).

Cronkhite-Canada syndrome is characterized by gastrointestinal hamartomatous polyposis, alopecia, onychodystrophy, skin hyperpigmentation, and diarrhea. It is associated with high morbidity (summary by Sweetser et al., 2012).

Sjogren syndrome is an autoimmune disease that mainly affects the exocrine glands. It is clinically characterized by keratoconjunctivitis sicca and xerostomia (Goransson et al., 2006). See 200400 for association of Sjogren syndrome with achalasia in sisters.

An EEC syndrome characterized by autosomal dominant inheritance that has material basis in variation in the chromosome region 7q11.2-q21.3.

The TP63-related disorders comprise six overlapping phenotypes: Ankyloblepharon-ectodermal defects-cleft lip/palate (AEC) syndrome (which includes Rapp-Hodgkin syndrome). Acro-dermo-ungual-lacrimal-tooth (ADULT) syndrome. Ectrodactyly, ectodermal dysplasia, cleft lip/palate syndrome 3 (EEC3). Limb-mammary syndrome. Split-hand/foot malformation type 4 (SHFM4). Isolated cleft lip/cleft palate (orofacial cleft 8). Individuals typically have varying combinations of ectodermal dysplasia (hypohidrosis, nail dysplasia, sparse hair, tooth abnormalities), cleft lip/palate, split-hand/foot malformation/syndactyly, lacrimal duct obstruction, hypopigmentation, hypoplastic breasts and/or nipples, and hypospadias. Findings associated with a single phenotype include ankyloblepharon filiforme adnatum (tissue strands that completely or partially fuse the upper and lower eyelids), skin erosions especially on the scalp associated with areas of scarring, and alopecia, trismus, and excessive freckling.

Achalasia is a primary motor disorder of the esophagus. It is characterized by aperistalsis and a failure of the lower esophageal sphincter to relax due to a loss of inhibitory nitrinergic neurons in the esophageal myenteric plexus. Patients typically present with dysphagia, regurgitation, retrosternal pain, and substantial weight loss (summary by Farrokhi and Vaezi, 2007 and Gockel et al., 2010).

Hypohidrotic ectodermal dysplasia (HED) is characterized by hypotrichosis (sparseness of scalp and body hair), hypohidrosis (reduced ability to sweat), and hypodontia (congenital absence of teeth). The cardinal features of classic HED become obvious during childhood. The scalp hair is thin, lightly pigmented, and slow growing. Sweating, although present, is greatly deficient, leading to episodes of hyperthermia until the affected individual or family acquires experience with environmental modifications to control temperature. Only a few abnormally formed teeth erupt, at a later-than-average age. Physical growth and psychomotor development are otherwise within normal limits. Mild HED is characterized by mild manifestations of any or all the characteristic features.

Yao syndrome (YAOS) is an autoinflammatory disease characterized by periodic fever, dermatitis, arthritis, and swelling of the distal extremities, as well as gastrointestinal and sicca-like symptoms. The disorder is associated with specific NOD2 variants (and Shen, 2017).

HELIX syndrome is an autosomal recessive disorder characterized by Hypohidrosis, Electrolyte imbalance, Lacrimal gland dysfunction, Ichthyosis, and Xerostomia (summary by Hadj-Rabia et al., 2018).

Ichthyotic keratoderma, spasticity, hypomyelination, and dysmorphic features (IKSHD) is characterized by epidermal hyperproliferation and increased keratinization, resulting in ichthyosis; hypomyelination of central white matter, causing spastic paraplegia and central nystagmus; and optic atrophy, resulting in reduction of peripheral vision and visual acuity (Mueller et al., 2019). In addition, patients exhibit mild facial dysmorphism (Kutkowska-Kazmierczak et al., 2018).

Kilquist syndrome (KILQS) is an autosomal recessive multisystem disorder characterized by neurologic, gastrointestinal, and secretory dysfunction. Affected individuals present at birth with hypotonia, feeding difficulties, mild dysmorphic features, and sensorineural hearing loss. They show poor overall growth associated with gastrointestinal anomalies such as gastroesophageal reflux or midgut malrotation, as well as profound global developmental delay with inability to sit or speak. Tear, sweat, and saliva production is also impaired, causing dry mouth and recurrent bronchial mucus plugging. Some of the clinical features are reminiscent of cystic fibrosis (CF; 219700) (summary by Stodberg et al., 2020).

Lacrimoauriculodentodigital syndrome-3 (LADD3) is a multiple congenital anomaly disorder characterized by aplasia, atresia or hypoplasia of the lacrimal and salivary systems, cup-shaped ears, hearing loss, and dental and digital anomalies (summary by Milunsky et al., 2006).

Lacrimoauriculodentodigital syndrome-1 (LADD1) is a multiple congenital anomaly disorder mainly affecting lacrimal glands and ducts, salivary glands and ducts, ears, teeth, and distal limb segments (summary by Rohmann et al., 2006). Genetic Heterogeneity of Lacrimoauriculodentodigital Syndrome LADD syndrome-2 (LADD2; 620192) is caused by mutation in the FGFR3 gene (134934) on chromosome 4p16, and LADD syndrome-3 (LADD3; 620193) is caused by mutation in the FGF10 gene, an FGFR ligand, on chromosome 5p12.