From OMIM
Neurodevelopmental disorder with neonatal respiratory insufficiency, hypotonia, and feeding difficulties (NEDRIHF) is characterized by severe hypotonia at birth associated with respiratory difficulties, including apnea and hypoventilation, and feeding difficulties. Many infants require ventilatory support or feeding tubes. Affected patients have global developmental delay, often never achieving walking or speech, although the severity can be variable. Additional common features may include seizures, exaggerated startle reflex, abnormal movements, and dysmorphic facial features. Brain imaging often shows hypomyelination and parenchymal atrophy. A subset of patients may have systemic features, such as cardiac defects, scoliosis, endocrine anomalies, constipation, or cryptorchidism (summary by Reijnders et al., 2018).  http://www.omim.org/entry/616158

From MedlinePlus Genetics
5q31.3 microdeletion syndrome is a condition characterized by severely delayed development of speech and motor skills, such as walking. Beginning in infancy, affected individuals also have weak muscle tone (hypotonia), feeding difficulties, and breathing problems. Breathing problems and difficulty swallowing (dysphagia) can be life-threatening.

5q31.3 microdeletion syndrome is also characterized by distinctive facial features. Such features include a narrow forehead, widely spaced eyes (hypertelorism), an open mouth with an upper lip that points outward (called a tented lip), a high arch in the roof of the mouth (high-arched palate), a small lower jaw (micrognathia), and a lack of facial expression. Some of these features, such as an open mouth with a tented lip and an expressionless face, are thought to be due to hypotonia.

Recurrent seizures (epilepsy) and seizure-like episodes (which can include muscle jerking, twitching, and stiffening), are common in 5q31.3 microdeletion syndrome. Many individuals with 5q31.3 microdeletion syndrome have brain abnormalities, several of which are caused by reduced production of myelin or delayed maturation of myelin. Myelin is the protective covering that insulates nerves and ensures the rapid transmission of nerve impulses.  https://medlineplus.gov/genetics/condition/5q313-microdeletion-syndrome

From MedlinePlus Genetics
PURA syndrome is a condition characterized by intellectual disability and delayed development of speech and motor skills, such as walking. Expressive language skills (vocabulary and the production of speech) are generally more severely affected than receptive language skills (the ability to understand speech), and most affected individuals are unable to speak. People with PURA syndrome may learn to walk later than their peers; many are never able to walk. In infancy, affected infants have very weak muscle tone (hypotonia) and feeding difficulties. Problems with swallowing (dysphagia) can last throughout life. In addition, affected infants can be excessively sleepy (hypersomnolent), have a low body temperature (hypothermia), and have short pauses in breathing (apnea) or episodes of abnormally slow breathing (hypoventilation). These breathing problems usually go away after age 1.

Recurrent seizures (epilepsy) are also common in PURA syndrome. Seizures usually begin before age 5 with uncontrolled muscle jerks (myoclonus). Other types of seizures can develop, such as generalized tonic-clonic seizures, which involve loss of consciousness, muscle rigidity, and convulsions. In people with PURA syndrome, seizures are often difficult to control.

Other features in people with PURA syndrome can include abnormalities of the heart, eyes, urogenital tract, gastrointestinal tract, and skeleton. Some affected individuals have symptoms of a hormonal problem, such as early sexual development (precocious puberty) or low levels of vitamin D (which is a hormone).  https://medlineplus.gov/genetics/condition/pura-syndrome