SMARCB1 is mutated in additional tumors including malignant brain & kidney tumors in children. It seems that heterozygotes for mutations in the SMARCB1 gene have an increased risk to develop a malignant kidney tumor in early childhood but if they survive to adulthood, they may be predisposed to the development of schwannomas. One schwannomatosis patient had a mutation in exon 2 of the SMARCB1 gene. Another patient exhibited a novel germline deletion of the SMARCB1, because most SMARCB1 mutations are point or frameshift. In this patient genetic analysis from different schwannomas indicated  inactivation of both the SMARCB1 and NF2 genes. Schwannomatosis is known to be a genetic disorder. However, familial occurrence is inexplicably rare. Diagnosis
Prenatal
Schwannomatosis can be tested prenatally on the NHS. Postnatal
Ferner et al. give the following diagnostic criteria for Schwannomatosis:

Definite
Age >30 years and ≥2 nonintradermal schwannomas, at least one with histologic confirmation and no evidence of vestibular tumor on MRI scan and no known NF mutation, or
One nonvestibular schwannoma plus a first-degree relative with schwannomatosis
Possible
Age <30 and ≥2 nonintradermal schwannomas, at least one with histologic confirmation and no evidence of vestibular tumor on MRI scan and no known NF mutation, or
Age >45 and ≥2 nonintradermal schwannomas, at least one with histologic confirmation and no symptoms of 8th nerve dysfunction and no NF2, or
Nonvestibular schwannoma and first-degree relative with schwannomatosis
Segmental.
Hypohidrosis is a disorder in which a person exhibits diminished sweating in response to appropriate stimuli. In contrast with hyperhidrosis, which is a socially troubling yet often benign condition, the consequences of untreated hypohidrosis include hyperthermia, heat stroke and death. An extreme case of hypohidrosis in which there is a complete absence of sweating and the skin is dry is termed anhidrosis. Causes
Diagnosis
Sweat is readily visualized by a topical indicator such as iodinated starch (Minor test) or sodium alizarin sulphonate, both of which undergo a dramatic colour change when moistened by sweat. A thermoregulatory sweat test can evaluate the body’s response to a thermal stimulus by inducing sweating through a hot box ⁄ room, thermal blanket or exercise. Failure of the topical indicator to undergo a colour change during thermoregulatory sweat testing indicates hypohidrosis, and further tests may be required to localize the lesion. Magnetic resonance imaging of the brain and ⁄ or spinal cord is the best modality for evaluation when the lesion is suspected to be localized to the central nervous system. Skin biopsies are useful when anhidrosis occurs as part of a dermatological disorder. Biopsy results may reveal the sweat gland destruction, necrosis or fibrosis, in addition to the findings of the primary dermatological disorder. Management
The treatment options for hypohidrosis and anhidrosis are limited. Those with hypohidrosis should avoid drugs that can aggravate the condition (see "Medications", under § Causes).