User:Dakoolen/17q21.31 Microdeletion Syndrome

17q21.31 microdeletion syndrome

Introduction

The 17q21.31 Microdeletion Syndrome is a syndrome caused by the deletion of a small piece of chromosome 17. The deletion occurs at a location designated q21.31 i.e., on the long arm of one of the pair of chromosomes 17. It has a prevalence estimated at 1:16000. The syndrome was described independently by three groups (Seattle, Cambridge and Nijmegen) in 2006.

caused by a 500-650 kilobase of

Clinical Characteristics

The syndrome is characterized by developmental delay/mental retardation, dysmorphisms, congenital malformations, and behavioral features. Global psychomotor developmental delay is noted in all individuals from an early age. The level of developmental delay varies significantly. Other findings include epilepsy (55%), congenital heart defects (39%), renal and urologic anomalies (37%), and cryptorchidism (71% of males). Behavior in most is described as friendly, amiable, and cooperative.

Diagnosis

The diagnosis is confirmed by demonstration of a 500-650 kb heterozygous deletion at chromosome 17q21.31 using any molecular method that determines the copy number of genomic sequences within the deleted region. Note: The 17q21.31 deletion cannot be identified by routine analysis of G-banded chromosomes or other conventional cytogenetic banding techniques.

Inheritence

The 17q21.31 microdeletion syndrome is inherited in an autosomal dominant manner, but to date almost all cases result from a de novo deletion. Thus, most affected individuals are simplex cases, i.e., a single occurrence in a family. The recurrence risk for future pregnancies is low (probably <1%) but greater than that of the general population because of the possibility of germline mosaicism.

Genes

The deletion encompasses 6 known genes, including CRHR1 and MAPT.

External links

Research website

• 17q21.31 Research Project

Chromosome 17 support groups

• C17 support group
• chromo17europe.webs.com/ Chromo 17 Europe

Sites/organizations providing information on 17q21.31 deletions

• Orphanet
• Unique
• GeneTests