However, it is the recognition of these minor malformations that might lead to the early detection of a genetic condition and prompt intervention for the child and family. The midpoint of the body is at about the level of the umbilicus in the newborn. As a child grows, this shifts downwards so that by maturity the midpoint is at the upper border of the symphysis pubis. The arm span is usually equal to the standing height. This is an autosomal dominant disorder.
Diastrophic dwarfism is an autosomal recessive disorder.
If a child has achondroplasia secondary to a new mutation, the risk of recurrence in future sibs would be negligible. The converse of short stature is tall stature, a clinical feature seen in patients with Marfan syndrome . Individuals with this condition are taller than average, with long arms and legs relative to trunk. When all three cardinal features are present, the diagnosis is relatively easy to make. A family history showing first or second degree relatives with features of this condition is also helpful in making the diagnosis in the proband.