Martin-Bell syndrome

A syndrome comprising X-linked mental retardation in children with macroorchidism, prognathism, hypotonia and autism, and a characteristic but variable facies. Appears in boys (homozygous in the first year of life). In puberty there is pronounced growth of testes. abnormal speech pattern, large ears, long face, high-arched palate, and malocclusion. Additional abnormalities may include lordosis, heart defect, pectus excavatum, flat feet, shortening of the tubular bones of the hands, and joint laxity. Heterozygous females have a broad range of dysfunctions.

Marin and Bell in 1943 described a large pedigree without knowledge of the cytogenetic anomaly and without considering the microorchidism. Sutherland in 1977 described a method for a secure and constant «Darstellung» of the fragile point.

Renpenning's syndrome differs from Martin-Bell in the absence of any fragile site on the X-chromosome. Renpenning’s cases (short stature, moderate microcephaly, neurological disorders) were reported in a Dutch Mennonite pedigree from Alberta and Saskatchewan. Escalante's syndrome is the fragile X type. This term has been used in Brazil and other South American countries.

• J. P. Martin, J. Bell:
  A pedigree of mental defect showing sex linkage.
  Journal of Neurology, Neurosurgery and Psychiatry, London, 1943, 6: 154-156.
• H. Renpenning, J. W. Gerrard, W. A. Zaleski, T. Tabata:
  Familial sex-linked mental retardation.
  Canadian Medical Association Journal, Ottawa, 1962, 87: 954-956.
• H. A. Lubs:
  A marker-X chromosome.
  American Journal of Human Genetics, Chicago, 1969, 21: 231.
• J. A. Escalante:
  Estudio genético de deficiencia mental. Doctoral thesis, Sao Paulo, 1971.
• J. A. Escalante, et al:
  Severe sex-linked mental retardation.
  Proc II Cong International Study Ment Deficiency, Warsaw, 1970, page 745.
• J. A. Escalante, H. Grunspun, O. Frota-Pessoa:
  Severe sex-linked mental retardation.
  Journal de génétique humaine, Geneva, 1971, 19: 137.
• G. R. Sutherland:
  Fragile sites on human chromosomes: Demonstration of their dependance on the type of tissue culture medium.
  Science, 1977, 197: 265-266.
• J. M. Opitz, G. R. Sutherland:
  Conference Report: Internatonal workshop on the fragile X and X-linked mental retardation.
  American Journal of Medical Genetics, New York, 1984, 17: 5-94.
• J. M. Opitz, J. F. Reynolds, L. M. Spano, editors:
  X-linked mental retardation 2.
  American Journal of Medical Genetics, New York, 1986, 23: 1-735.