Laron syndrome E34.3

Laron et al., 1966

Disturbance of motor growth with muscle weakness, pubertas tarda, facial dysmorphia, tooth development disorders, hip dysplasia and hypotrichosis.

Rarely. Worldwide, 200-300 cases have been described, mostly in patients of Semitic ethnicity. Commonly occurring in families with kosanguine compounds.

Autosomal recessive mutations of the GHR gene (growth hormone receptor gene; gene locus: 5p13-p12) and the STAT5B gene (= signal transducer and activator of transcription 5B gene; gene locus: 17q11.2) with defects of the GH receptor. This results in disturbances of the downstream cascade. The GHR gene codes for the " insulin-like growth factor-1 (IGF-1)", which binds to a receptor on the cell surface (IGF-1R). IGF-1R is a regulator of cell proliferation during the development of the hair follicle. The faulty cascade leads to developmental disorders of the hair follicle with consecutive hair shaft abnormalities.

Women and men are affected about equally often.

• Integument: Sparse hair as well as hair anomalies such as pili torti et canaliculi, longitudinal furrowing of the hair (see pili bifurcati), tapered hair shafts and proximal trichorrhexis nodosa. Hypohidrosis.
• Extracutaneous manifestations: motor growth disorders (muscle weakness, growth retardation), facial dysmorphia, tooth development disorders, hip dysplasia, pubertas tarda.

Highly increased HGH and decreased IGF-1 in the IGF-1 regeneration test. Often hypoglycaemia and hypercholesterolaemia.

Cooperation with pediatricians and endocrinologists. Symptomatic therapy of skin symptoms if necessary. Substitution of IGF-1 is successful in many cases.

1. Laron Z, Mannheimer S, Pertzelan A, Nitzan M (1966) Serum growth hormone concentration in full term infants. Isr J Med Sci 2: 770-773
2. Laron Z, Pertzelan A, Mannheimer S (1966) Genetic pituitary dwarfism with high serum concentation of growth hormone"a new inborn error of metabolism" Isr J Med Sci 2: 152-155
3. Laron Z, Weinberger D (2004) Diabetic retinopathy in two patients with congenital IGF-I deficiency (Laron syndrome). Eur J Endocrinol 151: 103-106
4. Laron Z (2015) Lessons from 50 Years of study of Laron syndromes. Endocr Pract 21:1395-1402.
5. Lurie R et al (2004) Laron syndrome (primary growth hormone insensitivity): a unique model to explore the effect of insulin-like growth factor 1 deficiency on human hair. Dermatology 208: 314-318