A nurse working in a preschool has just been advised that a toddler with fragile X syndrome has been admitted to the school. The nurse should advise the teacher that the child may exhibit which of the following characteristics?

Fragile X Syndrome (FXS) is caused by a mutation in the FMR1 gene on the X chromosome, which normally produces a protein (FMRP) essential for brain development. In FXS, this gene is either silenced or doesn’t produce enough of the protein, leading to developmental challenges.

Rationale for correct answer:
B. Aggressive behavior is common in fragile X syndrome. Children may exhibit aggression toward themselves or others, often triggered by stress, overstimulation, or difficulty with communication. This is a key behavioral manifestation educators and nurses should anticipate.

Rationale for incorrect answers:

A. Lordotic posturing is not a typical finding. Lordosis is more associated with musculoskeletal or spinal conditions.

C. Two different eye colors is called heterochromia, which is unrelated to fragile X syndrome.

D. Asynchronous breathing is not associated with fragile X. Breathing irregularities are not part of the syndrome’s typical manifestations.

Take home points

• Fragile X syndrome is the most common inherited cause of intellectual disability.
• Key features include: intellectual disability, speech and developmental delays, social anxiety, hyperactivity, and behavioral issues including aggression.
• Physical features may include a long face, large ears, and macroorchidism (after puberty).
• Nurses and teachers should be prepared to implement behavioral support strategies and foster structured, low-stress environments.

Down syndrome is a genetic condition caused by the presence of an extra copy of chromosome 21, which is why it's also called trisomy 2A. This additional genetic material affects how the body and brain develop, leading to a range of physical, cognitive, and developmental differences.

Rationale for correct answers:
B. Protruding tongue is common in infants with Down syndrome, often due to hypotonia and a relatively small oral cavity.

D. Wide, flat nasal bridge is a typical facial characteristic of Down syndrome, helping distinguish craniofacial appearance in affected infants.

Rationale for incorrect answers:

A. Elongated face is not characteristic of Down syndrome. It is more commonly seen in conditions like Marfan syndrome.

C. Infants with Down syndrome typically have small, low-set ears, not large or high-set.

E. Asymmetric Moro reflex usually suggests birth injury such as brachial plexus injury or clavicle fracture rather than Down syndrome.

Take home points

• Classic Down syndrome features in newborns include: hypotonia, protruding tongue, wide flat nasal bridge, small ears, simian crease, and upslanting palpebral fissures.
• Differentiating features are important because other syndromes (e.g., trisomy 13 or 18, Marfan syndrome) have distinct facial/physical characteristics.
• Early recognition allows timely screening for associated conditions such as congenital heart disease, GI anomalies, and thyroid dysfunction.