Definition

Rhabdoid tumor predisposition syndrome (RTPS1; OMIM #609322, RTPS2; OMIM #613325) is a rare syndrome that can lead to highly-aggressive, atypical teratoid/rhabdoid tumors (AT/RT) of the central nervous system and to malignant rhabdoid tumors (MRT) of other – usually renal – tissues in very young children.

Key Data

< swipe to see entire table >
Synonym
Genes SMARCB1 (RTPS1), more rarely SMARCA4 (RTPS2)
Gene products SMARCB1 (also INI1 or BAF47), SMARCA4 (also BRG1)
Function Part of the SWI/SNF chromatin remodeling complex, which serves to restructure nucleosomes, thereby releasing binding sites for DNA-binding proteins to allow transcription, replication, and DNA repair.
Heredity Autosomal dominant
Prevalence Unknown
Incidence of MRT: 0.6/1 million children (5/1 million in the first year of life; 0.04/1 million at age 10-14)
Incidence of AT/RT: 0.7/1 million children (5.4/1 million in the first year of life)
Genotype-phenotype correlation SMARCB1: rhabdoid tumor (usually loss-of-function mutations, LOF), schwannomatosis (missense), multiple meningiomas (missense), Nicolaides–Baraitser syndrome (missense), Coffin–Siris syndrome (missense), malignant peripheral nerve sheath tumor (LOF)

SMARCA4: MRT (LOF), AT/RT (LOF), small cell ovarian carcinoma, hypercalcemic type (LOF), Coffin-Siris syndrome (missense)

Penetrance Unknown; lower level of penetrance for AT/RT with SMARCA4 mutations than with SMARCB1 mutations
< swipe to see entire table >

Diagnosis

All patients that exhibit an MRT or AT/RT should undergo a genetic examination to check for the existence of an SMARCB1 or SMARCA4 mutation. In addition, all biological relatives of a person with a proven SMARCB1 or SMARCA4 mutation should be tested.

It is not always easy to demonstrate by histological means, since there is a variable pattern of undifferentiated “small round blue cells” with mesenchymal and epithelial components and classic rhabdoid cells, in some cases the latter may also be lacking.

The loss of the SMARCB1 and SMARCA4 proteins can be proven using immunohistochemical methods, which may help to establish the diagnosis.

Differential Diagnoses

  • Epithelioid sarcoma

  • Chordomas

  • Myoepithelial carcinoma of the soft tissues

  • Other brain tumors and solid tumors

Clinical Presentation

< swipe to see entire table >
Diseases with RTPS Gene
Rhabdoid tumors

  • AT/RT SMARCB1, SMARCA4
  • MRT (renal and extrarenal)
Depending on the disease:

SMARCB1, SMARCA4
SMARCB1
, SMARCA4

Schwannomatosis SMARCB1
Plexus carcinoma SMARCB1
Medulloblastoma SMARCB1
Multiple meningiomas SMARCB1
Nicolaides-Baraitser syndrome SMARCB1
Coffin-Siris syndrome SMARCB1, SMARCA4
Malignant peripheral nerve sheath tumor SMARCB1
Small cell ovarian carcinoma, hypercalcemic type (SCCOHT) SMARCA4
< swipe to see entire table >

Most MRT and AT/RT occur by age 3, although it is also possible for them to occur even later. Female patients with SMARCA4 mutations also have an increased risk of developing small cell ovarian carcinoma, hypercalcemic type, but not until adolescence or adulthood.

It is not uncommon for those affected to develop multiple primary tumors.

The prognosis is very poor both for AT/RT and MRT as well as for SCCOHT, with a 5-year survival rate of 10-30% and 33%, respectively.

Therapeutic Considerations

The treatment of patients with AT/RT and MRT as part of RTPS is no different from the treatment of patients with sporadic rhabdoid tumors.

Surveillance Recommendations

Surveillance Recommendations

There are no standardized recommendations to date.

The American Association for Cancer Research suggests the following:

For carriers of a truncating SMARCB1 mutation:

  • Cranial MRI every three months, from early infancy until 5 years of age

  • Abdominal/renal ultrasound every three months, from early infancy until 5 years of age

For female carriers of a truncating SMARCA4 mutation:

  • Abdominal ultrasound every 6 months for younger women

  • Prophylactic ovariectomy for older women

The European Rhabdoid Registry (EU-RHAB) suggests the following:

For carriers of a truncating SMARCB1 mutation:

0-1 year:

  • Cranial and abdominal ultrasound every month

  • If the quality is insufficient: MRI every 2-3 months

1-5 years:

  • MRI of the CNS and spinal axis (plus whole-body if necessary) every 2-3 months

  • Abdominal and pelvic ultrasound (or MRI) every 3 months

Additional Information

Open Clinical Trials / Registries

Support Groups

Unfortunately, we are as yet unaware of any existing support groups for patients with rhabdoid tumor predisposition syndrome (RTPS) deficiency. We will add new information as it becomes available.