A vegan couple accused of neglecting their toddler who was allegedly found to be suffering from rickets has faced court holding hands.

Police allege the father, 33 and mother, 31, fed their 20-month-old girl a strict diet 'severely lacking in nutrients for her to thrive.'

Detectives from the New South Wales State Crime Command's Child Abuse and Sex Crimes Squad started an investigation after the infant suffered a seizure on March 10.

Police allege this father, 33 and mother, 31, fed their 20-month-old girl a strict diet 'severely lacking in nutrients for her to thrive'. They have both been charged with neglecting the toddler

The accused couple left Waverley Local Court holding hands on Wednesday morning

Police claim the couple's child was malnourished, suffering from rickets (pictured is a stock image) and her height and weight were 'markedly below expected' for a girl her age

The couple was arrested on April 6, and police claimed the child was malnourished and suffering from rickets.

Rickets is a condition which results in weak or soft bones in children and can include symptoms such as bowed legs and stunted growth. The most common cause is vitamin D deficiency.

Police claimed the baby's height and weight were 'markedly below expected' for a child her age.

The couple appeared briefly at Waverley Local Court on Wednesday when their case was adjourned to the Downing Centre on July 31.

They held hands and left the court together without commenting.

The parents are charged with failing to provide for a child, causing damage or serious injury and reckless grievous bodily harm.

Police allege the couple 'did have parental responsibility for (the child) and without reasonable excuse, recklessly failed to provide for (the child) with the necessities of life, which caused a danger of serious injury to (the child).'

The parents are charged with failing to provide for a child, causing damage or serious injury and reckless grievous bodily harm. They have pleaded not guilty to all charges

The couple was living in this a well-maintained terrace house in Sydney's eastern suburbs when they were arrested last month; the father's BMW is parked outside on the street

A neighbour said the man was paying about $1,000 rent a week for the family's eastern suburbs home, and had seen the man putting the girl into this the grey BMW 125i coupe

The alleged offences occurred over 20 months between July 2016 and March 10 this year, at two locations in Sydney's east and south.

Both mother and father have pleaded not guilty.

An apprehended violence order has been filed on behalf of the 20-month-old against her parents.

That matter was also mentioned in court on Wednesday.

Former neighbours of the couple revealed last month they were unaware there was a baby living in their house.

The family moved into a neat terrace house in an exclusive neighbourhood in Sydney's eastern suburbs several months ago.

An apprehended violence order has been filed on behalf of the 20-month-old against her parents, pictured leaving Waverley Local Court on Wednesday morning

Outside the front door of the couple's home in Sydney's eastern suburbs were three pairs of adult runners and a pair of size 12 children's shoes (pictured)

A neighbour of the accused couple when they lived in a modest brick home in Sydney's south (pictured) said he only saw two boys, aged about five and three in the house

One neighbour of the couple when they lived in a modest brick home in Sydney's south said they only saw two boys, aged about five and three.

That neighbour believed the family moved out just three weeks before they were arrested and was shocked to hear allegations the couple had neglected their child.

'We get along well with all our neighbours but they had always kept to themselves,' he told Daily Mail Australia.

'So we didn't like to push it.'

'We got the shock of our life when the police told us there was a baby in there.'

'We never heard any mistreatment. There was always a bit of crying from the youngest boy but we never had any idea there was a baby in there.'

A BMW 125i couple a neighbour said belonged to the man was sitting outside the couple's home in Sydney's eastern suburbs after their arrest last month

Detectives from the New South Wales State Crime Command's Child Abuse and Sex Crimes Squad started an investigation into the couple after the infant suffered a seizure on March 10

The neighbour had not seen a woman in the house - a single-storey red brick home with a steel fence and an overgrown garden - for years.

'We haven't seen the wife for two years,' he said.

He had only seen the two boys about three times in the four or five years the family lived there, and described the man who lived in the house as quiet but pleasant.

'He seemed a nice style of a fellow,' he said.

'We'd see him going in and out. He'd say "G'day" if he walked into you.'

'We never heard any physical abuse whatsoever. When he spoke to [the boys] it was always with a very quiet voice.'

WHAT IS RICKETS? - Rickets is a disease causing soft and weakened bones in young children - The disease is caused by a lack of Vitamin D, calcium or phosphorus - Vitamin D deficiency can be caused by diet or inadequate sunlight exposure Signs and Symptoms: - Painful bones, muscle weakness, cramps and spasms - Slowed growth and development - Increased risk of broken bones, including spontaneous breaks that occur by themselves without pressure or trauma - Dental problems such as teeth failing to form or being slow to emerge, deformed teeth or soft tooth enamel - Prominent forehead and a large front fontanelle (soft spot) in infants - Deformities of the skeleton such as bowed legs, kyphosis ('hunch-back'), scoliosis (sideways curves of the spine), outward jutting breastbone or abnormal skull shape Source: Victoria State Goverment Advertisement

The couple's new home is a well-maintained terrace house in Sydney's affluent eastern suburbs, and the man's BMW could be seen parked on the street last month.

Outside the front door were three pairs of adult runners and a pair of size 12 children's shoes.

One of their new neighbours said he had seen a girl about 18 months old in the company of a man, often leaving the house about 8.30am to 9am.

'She was always well-dressed, just like a normal child,' he said.

'He seemed like an ordinary fella. I often see them coming out. He's only been there a month or six weeks.

'They seemed to be going to a day care centre. He just seemed like a normal working person.'

The neighbour, who described the street as 'nice and quiet', said no one had noticed anything usual, but added he had never seen the girl with a woman.

'I've never seen a woman in there. Never ever. You don't see any sort of movement in there.

'The child never cried. She seemed quite happy. She seemed like a healthy child.

'The child was in no distress. She didn't seem malnourished. The child seemed really normal.

'I can't believe it.'

The neighbour said the man was paying about $1,000 rent a week and he had seen him putting the girl into the grey BMW 125i coupe.

He had not spoken to the man at any length. 'A couple of times, just to say hello,' he said.