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corticospinal fibers, lack of inter-hemispheric inhibition between the two motor

cortices, and functional defects in motor planning and execution (Fig. 7.7).

28. Can clinical phenotype guide the selection of genetic testing for Kallmann
    syndrome?
    Although Kallmann syndrome can be associated with a wide variety of nonre-
    productive abnormalities, the presence of certain phenotypic characteristics
    points toward a specific mutation. The presence of synkinesia should prompt
    evaluation for KAL1 gene mutation, dental agenesis, and skeletal abnormalities
    for FGF8/FGFR1 and hearing loss for CHD7.


29. What are the causes of Kallmann syndrome with short stature?

Kallmann syndrome is typically associated with tall stature due to delayed

epiphyseal closure as a result of gonadal steroid deficiency. However, those

with FGFR1 mutations have short stature, despite hypogonadotropic

hypogonadism.

30. A 10-year-old obese boy was brought with complaint of small size of penis.
    What to do next?
    A diagnosis of micropenis is inadvertently made in obese children, as penis is
    buried in surrounding fat, giving an impression of apparently small-sized

Normal Pathological

?

Fusion

disorder

a b

Fig. 7.7 (a) Normal pattern of decussation of corticospinal fibers, (b) partial failure of decussa-
tion of corticospinal fibers in patients with Kallmann syndrome results in synkinesia

7 Delayed Puberty