Silver–Russell syndrome

Silver–Russell syndrome (SRS), sometimes called Silver–Russell dwarfism, is a rare congenital growth disorder. In the United States, it is more commonly referred to as Russell–Silver syndrome, while elsewhere it is called Silver–Russell syndrome. It belongs to a group of 200 types of dwarfism and is one of five types of primordial dwarfism. The condition affects about one in every 50,000 to 100,000 births, and it occurs equally in males and females.

**Signs and symptoms** There is no definitive test to confirm SRS in every case, though many individuals have a specific genetic marker. Instead, a diagnosis is usually made in children who show several of the following symptoms. The most noticeable early sign is intrauterine growth restriction (IUGR), combined with other features. These include being small for gestational age at birth (often weighing less than 2.8 kg, or two or more standard deviations below the average weight of 2.8 kg). Infants may have feeding problems, showing little interest in eating and taking only small amounts with difficulty. Hypoglycemia is common, as is excessive sweating, especially at night, along with pale or grayish skin—this can signal low blood sugar. The face is often triangular, with a small jaw and pointed chin that tends to become less pronounced with age, and the mouth may curve downward. Younger children may have a blue tint to the whites of their eyes. Head circumference is often normal, making it look large compared to the small body. The fontanelle (soft spot) may be wide and close later than usual. Clinodactyly (curved fingers) is common. Body asymmetry occurs, with one side growing more slowly than the other. Growth remains poor, with no "catch-up" to normal growth curves, resulting in a low BMI. Other possible symptoms include precocious puberty, low muscle tone, gastroesophageal reflux disease, a notable lack of subcutaneous fat, constipation (sometimes severe), and, rarely, heart defects such as ventricular or atrial septal defects. The earliest signs are growth-related, typically noticed at birth and persisting throughout life. Children with SRS may initially grow at a normal rate for their age but rarely catch up to average size later in childhood. Without growth hormone treatment, average adult height is about 4 feet 11 inches (149.9 cm) for males and 4 feet 7 inches (139.7 cm) for females.