Evaluation of the Child with Developmental Delay
By Beth A. Pletcher, MD, March 1998

• Perinatal factors may increase risks for learning disabilities and therefore pregnancy and birth histories are important in the evaluation of a child with developmental delay. Prematurity, RDS with ventilatory support and evidence of intraventricular hemorrhages are three such factors.

• Family history of females with significant learning disabilities or males/females with mental retardation increases concern about possible genetic factors.

• Family history of recurrent miscarriages, stillbirths, neonatal deaths, children with birth defects and/or failure to thrive increases concern about a possible chromosomal variation such as a balanced translocation leading to chromosomally unbalanced offspring.

• Males with mental retardation and/or autism without birth defects, especially on the maternal side of the family increases suspicion for Fragile X syndrome.

• Any evidence of developmental regression or loss of milestones prompts a more thorough metabolic work-up. Children with inborn errors of metabolism may or may not have other systemic symptoms such as: seizures, hepatosplenomegaly, short stature, cataracts, obstructive sleep apnea, hirsutism, delayed dental eruption, joint abnormalities (contractures/laxity) or kyphosis/scoliosis.

• In all males with significant developmental delay of unknown cause, a chromosome analysis and molecular test for fragile X should be considered. Detection rates for Fragile X syndrome or a chromosome variation approximate 8% (4% for each) in this clinical setting.

• Recommendations for females with developmental delay is less clear, but a chromosome analysis should be considered if short stature, microcephaly or dysmorphic features are present. Even for girls with mild learning disabilities, fragile X testing should be considered if there is a maternal family history of males with mental retardation.

• Chromosome analysis is performed on blood collected in a green top tube (Na heparin) and DNA testing for fragile X is performed on blood collected in a purple top tube (EDTA).