Fragile X Syndrome: This is a genetic condition causing intellectual disability, behavioral and learning challenges, and various physical characteristics such as a long and narrow face, high-arched palate, and low-set ears. It is the most common cause of inherited intellectual disability.

Down Syndrome: Characterized by intellectual disability, distinctive facial features (which can include a flat face rather than a tall one, but there's variability), and low-set ears. While the facial features don't perfectly match, the combination of intellectual disability and dysmorphic features makes it a consideration.
Prader-Willi Syndrome: This genetic disorder causes a range of symptoms including intellectual disability, distinctive facial features, and short stature. Early infancy features can include a narrow forehead, almond-shaped eyes, and a thin upper lip, which might not directly align with "tall face" but warrants consideration due to the intellectual disability and potential for dysmorphic features.
Williams Syndrome: Known for its distinctive "elfin" facial features, intellectual disability, and friendly demeanor. Facial features can include a broad forehead, short nose, full cheeks, and a wide mouth, which might not directly match "tall face" but is a condition with significant dysmorphia and intellectual disability.

Congenital Hypothyroidism: If untreated, can lead to intellectual disability and has physical features that might include a broad, flat nose and puffy face, which doesn't directly match "tall face" but is crucial to diagnose early due to the potential for severe intellectual disability if left untreated.
Phenylketonuria (PKU): An inherited disorder that can cause intellectual disability if not treated. While it doesn't typically cause dysmorphic facial features, the severity of intellectual disability if untreated makes it a critical diagnosis not to miss.

Sotos Syndrome: A rare genetic disorder characterized by excessive physical growth during the first few years of life, distinctive facial features (which can include a long, narrow face), and intellectual disability. The facial features and intellectual disability align with the question, but its rarity makes it less likely.
Marfan Syndrome: Primarily known for its effects on the cardiovascular system, it can also cause intellectual disability in some cases and has distinctive physical features including a tall, slender build and facial features that might include a long face. However, the primary features are more related to the skeletal and cardiovascular systems.
Klinefelter Syndrome: Characterized by an extra X chromosome in males, leading to features such as tall stature, intellectual disability, and sometimes dysmorphic features, though these are not as pronounced or consistent as in other syndromes listed here.