Manifestation of NER diseases

Approximately 25% of affected individuals with XP have neurologic manifestations (acquired microcephaly, diminished or absent deep tendon stretch reflexes, progressive sensorineural hearing loss, and progressive cognitive impairment). The most common causes of death are skin cancer, neurologic degeneration, and internal cancer. The median age at death in persons with XP with neurodegeneration (29 years) was found to be younger than that in persons with XP without neurodegeneration (37 years).

CS patients have manifestations related to growth, aging and hypersensitvity leading to skin cancer. Being a rare form of dwarfism, it is an inherited disorder whose diagnosis depends on the presence of: growth retardation, abnormal photosensitivity and prematurely aging (progeria).

Abnormalities caused due to TTD is mostly associated with XP, resulting in ocular manifestations like microcornea, microphthalmia, nystagmus, infantile cataracts and retinal/macular degeneration.

Epidemiology

The gene frequency for XP in the general population has been reported to be 1 in 200 million and the frequency of the disorder, 4 in 1 million. Countries like Libya, Egypt, Israel and Japan, with a high degree of consanguinity, have a high incidence of this disease. A similar level of consanguinity is seen in South India.

Worldwide statistical distribution of all skin cancers.

Latest incidence

• Country: India
• Case: Thirteen patients from 10 unrelated families with XP were referred to the ICMR Genetic Research Center, Mumbai for molecular diagnosis and counseling during the period 2011-2014. Consanguinity was observed in 6 of the 10 families. Five families each belonged to Maharashtra and Uttar Pradesh.